NRG Oncology Updated International Consensus Atlas on Pelvic Lymph Node Volumes for Intact and Postoperative Prostate Cancer

Ultra-hypofractionation for node-positive prostate cancer: pushing boundaries and redefining standards

Radiotherapy is a cornerstone in the management of node-positive prostate cancer. Advances in imaging modalities and radiation therapy techniques have led to the evolution of treatment standards for this patient population. This review aims to explore the therapeutic advancements of the past decade, with a focus on the role of ultra-hypofractionated radiotherapy in node-positive prostate cancer.

Pelvic Regional Control With 25 Gy in 5 Fractions in Stereotactic Radiation Therapy for High-Risk Prostate Cancer: Pooled Prospective Outcomes From the SHARP Consortium

PURPOSE

To evaluate the efficacy of 25 Gy in 5 fractions (25 Gy/5#) prophylactic pelvic nodal irradiation for regional control during stereotactic radiation therapy (SBRT) for high-risk prostate cancer.

METHODS AND MATERIALS

The multinational SHARP consortium database of patients treated with curative-intent prostate SBRT for high-risk prostate cancer was queried for prophylactic radiation therapy 25 Gy/5# to the pelvic lymph nodes. Details of Phoenix-defined biochemical failure and location of recurrence (local, regional, or distant) were extracted. Five-year biochemical failure-free survival (BFFS), metastasis-free survival, and overall survival were estimated by Kaplan-Meier method. Impact of potential prognostic factors (tumor stage, grade group [GG], prostate radiation therapy dose, and Androgen Deprivation Therapy (ADT) duration) was analyzed using Cox proportional hazards model.

RESULTS

A total of 171 patients were eligible for analysis. Two-thirds of the patients had GG 4-5 cancer. Prostate was irradiated to 40 Gy/5# in 51.5% of the cohort, whereas the rest received 35 to 36.25 Gy/5#. Median ADT duration was 15 months (IQR, 9-24). Over a median follow-up of 51 months, biochemical failure was recorded for 19 (11.1%) patients. Restaging with Prostate Specific Membrane Antigen (PSMA)-Positron Emission Tomography Computed Tomography (PETCT) showed recurrence within the pelvic nodes in 3 patients, all with co-occurring distant metastases. Overall pelvic control was 98.2%, with 5-year BFFS and overall survival being 86.1% and 89.3%, respectively. None of the prognostic factors showed a statistically significant impact on BFFS, except GG (adjusted HR 3.6 [95% CI, 0.9-13.0], P = .06).

CONCLUSIONS

For high-risk prostate cancer treated with SBRT, prophylactic pelvic nodal irradiation with 25 Gy/5# achieved near universal regional control.

Long-term outcomes of radiotherapy and impact of nodal disease burden in clinically node-positive prostate cancer

PURPOSE

The optimal management for pelvic clinical node-positive (cN1) prostate cancer remains controversial and randomized evidence for local therapy is lacking. Recent data suggest that common-iliac nodal metastases might carry a prognosis similar to that of cN1 disease when treated radically. In this context, we retrospectively reviewed the experience at our centre of treating cN1 prostate cancer, with or without common-iliac nodal metastases, focusing on the role of radiotherapy and the effect of nodal disease burden on survival.

MATERIALS AND METHODS

The study population consisted of men diagnosed with prostate cancer between 2002 and 2018 with cN1 disease and/or common-iliac nodal metastases and treated with androgen deprivation therapy and/or definitive local therapy. Outcomes of interest included overall survival and castration resistance-free survival, which were estimated using the Kaplan-Meier method. Univariable and multivariable Cox regression were used to identify factors associated with overall - and castration resistance-free survival. In the subgroup of patients treated with radiation, the association between a number of variables - including biologically effective dose to the prostate, use of elective pelvic nodal radiotherapy, and escalated dose (radiotherapy boost) to positive nodes-and overall survival was studied.

RESULTS

A total of 87 patients were included, of whom 14 had common-iliac nodal metastases and 68 received radiotherapy. Median follow-up was 110 months. On univariate analysis, radiotherapy was associated with improved overall survival (hazard ratio [HR]: 0.28, 95 % confidence interval [CI]: 0.14-0.55, P<0.0005) and castration resistance-free survival (HR: 0.22, 95 % CI: 0.12-0.41, P<0.0005). Median overall survival in those patients receiving radiotherapy was 134.9 versus 63.1 months in those not receiving radiotherapy. Receipt of radiotherapy remained significantly associated with overall survival on multivariable analysis (HR: 0.13, 95 % CI: 0.05-0.32, P<0.001). Biopsy Gleason score 10 and presence of more than two positive lymph nodes were associated with worse overall survival while presence of common-iliac nodal metastases was not found to have any significant association with overall survival. In patients treated with radiation, increasing the biologically effective dose to the prostate was associated with improved overall survival (HR: 0.73 per 10Gy, 95 % CI: 0.54-0.97, P=0.03) while use of elective pelvic nodal radiotherapy and use of a radiotherapy boost to positive nodes had no significant association with overall survival.

CONCLUSION

In this cohort, we evaluate the impact of radiotherapy in pelvic clinical node-positive prostate cancer that includes common-iliac nodal metastases. Receipt of radiotherapy was associated with improved oncologic outcomes. The number of positive pelvic nodes, but not their common-iliac location, was prognostic.

Incidence and predictors of lower extremity lymphedema after postoperative radiotherapy for prostate cancer

BACKGROUND

To assess the rate and predictors of lower extremity lymphedema (LEL) after radiotherapy (RT) following radical prostatectomy (RP) ± pelvic lymph node dissection (PLND) for prostate cancer.

METHODS

Patients (pts) treated with adjuvant or salvage RT after RP ± PLND and a minimum 2-year follow-up were included. LEL was defined as a volume difference ≥ 10% between limbs evaluated using circumferential measurements with a flexible non-stretch tape. The following predictors were investigated at logistic regression: age (continuous); body mass index (BMI, continuous); exercise level (low vs. medium/high); smoking (yes vs. no); cigarette pack/year (continuous); hypertension (yes ns no); vascular comorbidity (yes vs. no); diabetes (yes vs. no); PLND (yes vs. no); number of examined nodes (continuous); whole pelvis radiotherapy (WPRT) (yes vs. no); time between RP and RT (continuous); planning target volume (PTV) volume (continuous); PTV/BMI (continuous). Statistical significance was claimed for p < 0.05.

RESULTS

101 pts were examined. The median time from surgery to RT was 36.1 months (mths) (IQR: 15.0-68.3), the median time from RT to the date of study examination was 51.1 months (IQR: 36.8-65.3). 14 pts developed LEL (13.9%), 3 pts (2.9%) before RT, 11 pts (10.8%) after RT. The median time from RT to LEL was 4 mths (IQR: 0.5-17.3). At multivariable analysis (MVA) diabetes mellitus (DM) (OR = 32.8, p = 0.02), time between surgery and RT (OR = 0.966, p = 0.039) and exercise (OR = 0.03, p = 0.002) were independently correlated to LEL. The number of examined nodes was highly correlated to LEL at univariate analysis (OR = 1.066, p = 0.025) but was not confirmed at MVA (p = 0.719). Interestingly, the distribution of the examined nodes was statistically different between pts with low (median N = 12) vs. medium/high (N = 5) exercise (p = 0.034).

CONCLUSIONS

Clinically detectable LEL involves a minority of pts after RT. DM is a predisposing factor, while awaiting RT delivery has a protective effect favoring salvage over adjuvant RT.

NRG Oncology International Consensus Contouring Atlas on Target Volumes and Dosing Strategies for Dose-Escalated Pancreatic Cancer Radiation Therapy

PURPOSE

Dose-escalated radiation therapy is increasingly used in the treatment of pancreatic cancer; however, approaches to target delineation vary widely. We present the first North American cooperative group consensus contouring atlas for dose-escalated pancreatic cancer radiation therapy.

METHODS AND MATERIALS

An expert international panel comprising 15 radiation oncologists, 2 surgeons, and 1 radiologist was recruited. Participants used MimCloud software to contour high- and low-risk clinical target volumes (CTVs) on 3 pancreatic cancer cases: a borderline resectable head tumor, a locally advanced head tumor, and a medically inoperable tail tumor. Simultaneous Truth and Performance Level Estimation volumes were created, and contours were analyzed using Dice similarity coefficients.

RESULTS

The contoured gross tumor volume for the borderline head, locally advanced head, and unresectable tail tumor cases were 156.7, 58.2, and 9.0 cc, respectively, and the Dice similarity coefficients (SD) for the high- and low-risk CTV ranged from 0.45 to 0.82. Consensus volumes were agreed upon by authors. High-risk CTVs comprised the tumor plus abutting vessels. Low-risk CTVs started superiorly at (tail and distal body tumors) or 1 cm above (head, neck and proximal body tumors) the celiac takeoff and extended inferiorly to the superior mesenteric artery at the level of the first jejunal takeoff. For head, neck, and proximal body tumors, the lateral volume encompassed the entire pancreas head and 5 to 10 mm around the celiac, superior mesenteric artery, superior mesenteric vein, including the common hepatic artery and medial portal vein, consistent with a "Triangle" volume-based approach. For distal body and tail tumors, the entire tail was included, along with the splenic vessels and the takeoffs of celiac artery.

CONCLUSIONS

Through multidisciplinary collaboration, we created consensus contouring guidelines for dose-escalated pancreatic cancer radiation therapy. These volumes include not only gross disease, but also routine elective coverage, and can be used to standardize practice for future trials seeking to define the role of dose-escalated radiation therapy in pancreatic cancer.

Bladder Adjuvant Radiation Therapy (BART): Acute and Late Toxicity From a Phase III Multicenter Randomized Controlled Trial

PURPOSE

To report toxicity from the multicenter phase III randomized trial of Bladder Adjuvant Radiation Therapy (BART) after radical cystectomy and chemotherapy in high-risk muscle-invasive bladder cancer (MIBC).

METHODS AND MATERIALS

Patients with nonmetastatic urothelial MIBC with ≥1 high-risk feature after radical cystectomy- pT3-4, pN1-3, nodal yield <10, positive margin, or ≥cT3 downstaged with neoadjuvant chemotherapy- were randomized 1:1 to observation (Obs) or adjuvant radiation therapy (RT) at 4 centers, stratified by pN stage (N0, N+) and chemotherapy (neoadjuvant, adjuvant, none). Stoma-sparing image guided intensity modulated RT 50.4 Gy in 28# was prescribed to the cystectomy bed and pelvic nodes. Acute toxicity (≤3 months of RT/randomization) and late toxicity were assessed per protocol using Common Terminology Criteria for Adverse Event v5.0. Patients progressing within 3 or 6 months of randomization were excluded from acute or late toxicity analysis, respectively.

RESULTS

The BART trial enrolled 153 patients (Obs = 76, RT = 77). About half (49%) had pN+. Nearly 90% received chemotherapy (70% neoadjuvant; most commonly gemcitabine plus cisplatin). In the RT arm, 63/77 completed RT per protocol with no toxicity-related RT termination. Of the 134 patients analyzable for acute toxicity, no difference was observed in grade 3 (Obs 4.2% vs RT 1.6%, P = .34). Grade 2 effects were higher with RT (17.5% vs 1.1%, P < .001), mainly diarrhea/enteritis or proctitis. Late toxicity was analyzable for 104 patients (Obs = 57, RT = 47) with a median follow-up of 27 months. Grades 3 to 4 toxicity were about 10% (Obs 10.5% vs RT 8.4%, P = .62), and cumulative late grade 2+ toxicity was similar in both groups (17.5% vs 23.3%, P = .27).

CONCLUSIONS

In the largest trial of adjuvant RT for high-risk urothelial MIBC, severe acute and late toxicity were low and similar with obervation or radiation therapy. The oncological outcomes are awaited.

« Augmented radiotherapy » in the management of high-risk prostate cancer (PCa): A systematic review

BACKGROUND

In patients with high-risk (HR) prostate cancer (PCa) treated with radiotherapy and androgen deprivation therapy (ADT), intensification with androgen receptor pathway inhibitor (ARPI) improves overall survival (OS), at the cost of significant side-effects. We hypothesized that "augmented RT" schedules (defined as either dose-escalation on the prostate gland over 78 Gy and/or addition of whole pelvic radiotherapy (WPRT)), combined with long-term ADT can reach excellent prostate cancer specific survival (PCSS) in this population with little detrimental impact on quality of life.

METHODS

We searched Pubmed database until February 8, 2024. Studies reporting both oncological and toxicity outcomes after "augmented RT" were deemed eligible. Studies without ADT or with ARPI intensification were deemed ineligible.

RESULTS

Dose-escalation within the prostate gland at doses over 78 Gy halved the risk of biochemical recurrence at 5 years, with however no impact on PCSS. The addition of WPRT provides a 5-year disease-free survival (DFS) reaching 89.5 % at 5 years, with no significant increase in late grade≥ 2 genito-urinary (GU) or gastrointestinal (GI) toxicity. Combined approaches result in 9-year PCSS ranging between 96.1 % and 100 %. Most approaches demonstrated excellent safety profiles.

CONCLUSIONS

"Augmented RT" reached excellent oncological outcomes, with minimal additional toxicity. The development of biomarkers might lead to further treatment personalization, in the rapidly evolving landscape of systemic therapies.

Avoiding prostate bed radiation for the PSMA-PET detected nodal recurrence patient post prostatectomy

Background

Nodal only recurrence post radical prostatectomy (RP) is increasingly recognised in the PSMA scan era. Management is controversial with a curative approach usually incorporating prostate bed and nodal irradiation (PB + NRT) in combination with long-term hormonal therapy. It is unknown whether omitting prostate-bed irradiation (PBRT) is safe in a subgroup of these patients.

Purpose

To document the outcomes for pelvic nodal only salvage radiation therapy (NRT) plus concurrent androgen deprivation therapy (ADT) for patients with PSMA PET documented nodal relapses.

Methods and materials

Eligible patients included PSMA PET documented nodal only relapses post RP who received NRT with or without PBRT at Royal North Shore Hospital (NSCC), Gosford Hospital (CCCC) or Genesis Care (GC) between January 2015 and December 2021. Baseline demographics, surgical pathology, radiation details, ADT use and outcomes were documented.

Results

Forty-six patients were identified, 22 in the PB + NRT cohort and 24 in the NRT cohort. Compared to the PBRT + NRT group, the NRT cohort had lower stage disease (pT2 = 7 (29 %), pT3a = 15 (63 %), pT3b = 1 (4 %) vs pT2 = 0, pT3a = 10 (45 %), pT3b = 12 (55 %)) (p=<0.001) and lower rates of R1 resection (0 % vs 63.6 % (n = 14)) (p < 0.001) respectively. The median follow-up from radiotherapy was 3.9 years.Four-year biochemical failure- free survival (BFFS) was 64 % in the NRT group vs 67 % in the PB + NRT group. Of the ten (41.6 %) failures in the NRT group, 1 (4 %) was a biochemical failure only, 2 (8 %) recurred in the PB and received further salvage treatment, 4 (17 %) had nodal failure outside the pelvis and 3 (13 %) had distant metastases.One patient (4 %) in the NRT group recorded late grade ≥2 GU toxicity compared with 7 (32 %) in the PB + NRT. No patients in the NRT group recorded late grade ≥2 GI toxicity compared with 2 (9 %) in the PB + NRT cohort.

Conclusion

This study provides early evidence for the feasibility of PBRT sparing to avoid local toxicity. Most patients in this cohort failed distantly. This data suggests that for selected men PB-avoidance may be considered given informed consent.

Protocol-based CT-guided brachytherapy for patients with prostate cancer and previous rectal extirpation-a curative approach

OBJECTIVE

There are numerous curative treatment possibilities for prostate cancer. In patients who have undergone rectal extirpation for rectal cancer treatment, curative options are limited due to anatomic changes and previous irradiation of the pelvis. In this analysis, we validate the feasibility of CT-guided transperineal interstitial brachytherapy for this specific scenario.

PATIENTS AND METHODS

We analyzed the treatment procedures and outcomes of 5 patients with metachronic nonmetastatic prostate cancer. Ultrasound-guided brachytherapy was not possible in any of the patients. Of these 5 patients, 3 were treated for prostate cancer using temporary brachytherapy with Ir-192 only, and 2 were treated with external-beam radiation therapy and temporary brachytherapy as a boost. CT-guided brachytherapy was performed in all patients. We analyzed the feasibility, efficacy, treatment-related toxicity, and quality of life (EORTC-30, IEFF, IPSS, and ICIQ questionnaires) of the treatments.

RESULTS

Median follow-up was 35 months. Two out of five patients received boost irradiation (HDR 2 × 9 Gy, PDR 30 Gy). Three out of five patients were treated with PDR brachytherapy in two sessions up to a total dose of 60 Gy. Dosimetric parameters were documented as median values as follows: V100 94.7% (94.5-98.4%), D2bladder 64.3% (50.9-78.3%), D10urethra 131.05% (123.2%-141.2%), and D30urethra 122.45% (116.2%-129.5%). At the time of analysis, no biochemical recurrence had been documented. Furthermore, neither early nor late side effects exceeding CTCAE grade 2 were documented.

CONCLUSION

CT-guided transperineal brachytherapy of the prostate in patients with previous rectal surgery and radiation therapy is safe and represents a possible curative treatment option. Brachytherapy can be considered for patients with metachronic prostate cancer in this specific scenario, albeit preferably in experienced high-volume centers.

Comparison of Vendor-Pretrained and Custom-Trained Deep Learning Segmentation Models for Head-and-Neck, Breast, and Prostate Cancers

BACKGROUND/OBJECTIVES

We assessed the influence of local patients and clinical characteristics on the performance of commercial deep learning (DL) segmentation models for head-and-neck (HN), breast, and prostate cancers.

METHODS

Clinical computed tomography (CT) scans and clinically approved contours of 210 patients (53 HN, 49 left breast, 55 right breast, and 53 prostate cancer) were used to train and validate segmentation models integrated within a vendor-supplied DL training toolkit and to assess the performance of both vendor-pretrained and custom-trained models. Four custom models (HN, left breast, right breast, and prostate) were trained and validated with 30 (training)/5 (validation) HN, 34/5 left breast, 39/5 right breast, and 30/5 prostate patients to auto-segment a total of 24 organs at risk (OARs). Subsequently, both vendor-pretrained and custom-trained models were tested on the remaining patients from each group. Auto-segmented contours were evaluated by comparing them with clinically approved contours via the Dice similarity coefficient (DSC) and mean surface distance (MSD). The performance of the left and right breast models was assessed jointly according to ipsilateral/contralateral locations.

RESULTS

The average DSCs for all structures in vendor-pretrained and custom-trained models were as follows: 0.81 ± 0.12 and 0.86 ± 0.11 in HN; 0.67 ± 0.16 and 0.80 ± 0.11 in the breast; and 0.87 ± 0.09 and 0.92 ± 0.06 in the prostate. The corresponding average MSDs were 0.81 ± 0.76 mm and 0.76 ± 0.56 mm (HN), 4.85 ± 2.44 mm and 2.42 ± 1.49 mm (breast), and 2.17 ± 1.39 mm and 1.21 ± 1.00 mm (prostate). Notably, custom-trained models showed significant improvements over vendor-pretrained models for 14 of 24 OARs, reflecting the influence of data/contouring variations in segmentation performance.

CONCLUSIONS

These findings underscore the substantial impact of institutional preferences and clinical practices on the implementation of vendor-pretrained models. We also found that a relatively small amount of institutional data was sufficient to train customized segmentation models with sufficient accuracy.

Utilizing artificial intelligence for the detection of hemarthrosis in hemophilia using point-of-care ultrasonography

Background

Recurrent hemarthrosis and resultant hemophilic arthropathy are significant causes of morbidity in persons with hemophilia, despite the marked evolution of hemophilia care. Prevention, timely diagnosis, and treatment of bleeding episodes are key. However, a physical examination or a patient's assessment of musculoskeletal pain may not accurately identify a joint bleed. This difficulty is compounded as hemophilic arthropathy progresses.

Objectives

Our system aims to utilize artificial intelligence and ultrasonography (US; point-of-care and handheld) to enable providers, and ultimately patients, to detect joint bleeds at the bedside and at home. We aimed to develop and assess the reliability of artificial intelligence algorithms in detecting and segmenting synovial recess distension (SRD; an indicator of disease activity) on US images of adult and pediatric knee, elbow, and ankle joints.

Methods

A total of 12,145 joint exams, comprising 61,501 US images from 7 international healthcare centers, were collected. The dataset included healthy participants and adult and pediatric persons with hemophilia, with and without SRD. Images were manually labeled by 2 experts and used to train binary convolutional neural network classifiers and segmentation models. Metrics to evaluate performance included accuracy, sensitivity, specificity, and area under the curve.

Results

The algorithms exhibited high performance across all joints and all cohorts. Specifically, the knee model showed an accuracy of 97%, sensitivity of 96%, specificity of 97%, and an area under the curve of 0.97 in SRD. High Dice coefficients (80%-85%) were achieved in segmentation tasks across all joints.

Conclusion

This technology could assist with the early detection and management of hemarthrosis in hemophilia.

Fully automated radiotherapy treatment planning: A scan to plan challenge

BACKGROUND AND PURPOSE

Over the past decade, tools for automation of various sub-tasks in radiotherapy planning have been introduced, such as auto-contouring and auto-planning. The purpose of this study was to benchmark what degree of automation is possible.

MATERIALS AND METHODS

A challenge to perform automated treatment planning for prostate and prostate bed radiotherapy was set up. Participants were provided with simulation CTs and a treatment prescription and were asked to use automated tools to produce a deliverable radiotherapy treatment plan with as little human intervention as possible. Plans were scored for their adherence to the protocol when assessed using consensus expert contours.

RESULTS

Thirteen entries were received. The top submission adhered to 81.8% of the minimum objectives across all cases using the consensus contour, meeting all objectives in one of the ten cases. The same system met 89.5% of objectives when assessed with their own auto-contours, meeting all objectives in four of the ten cases. The majority of systems used in the challenge had regulatory clearance (Auto-contouring: 82.5%, Auto-planning: 77%). Despite the 'hard' rule that participants should not check or edit contours or plans, 69% reported looking at their results before submission.

CONCLUSIONS

Automation of the full planning workflow from simulation CT to deliverable treatment plan is possible for prostate and prostate bed radiotherapy. While many generated plans were found to require none or minor adjustment to be regarded as clinically acceptable, the result indicated there is still a lack of trust in such systems preventing full automation.

Safety and early efficacy of involved-field SBRT for nodal oligo-recurrent prostate cancer

Purpose

Following treatment for localized prostate cancer, a subset of men will develop recurrent disease in the abdominopelvic nodes. For radiation therapy (RT), the optimal treatment volume, fractionation schedule, and dose remain unanswered questions. We report early outcomes for patients treated with involved-field stereotactic body radiation therapy (SBRT) (IF-SBRT) for nodal oligo-recurrent (NOR) prostate cancer.

Methods

Between January 2018 and October 2023, 67 patients with a median age of 75 with NOR prostate cancer treated with 74 courses of IF-SBRT at Georgetown were eligible for this analysis. NOR was defined as any volume of disease that could be safely treated within an IF. All patients were treated with five-fraction IF-SBRT (27.5-35 Gy). The IF treatment volume was defined as the nodal basin containing the gross disease as well as the immediately adjacent basins. Disease progression was defined as a prostate-specific antigen (PSA) rise above the pretreatment baseline or initiation of a second treatment. Local control and progression-free survival were calculated using the Kaplan-Meier method.

Results

Detection of pre-SBRT NOR was ascertained by prostate-specific membrane antigen (PSMA) (38%), fluciclovine (50%), or MRI/CT (12%). Median follow-up was 50 months (1-262). The median pre-salvage PSA was 6.5 ng/mL (range, 0.1-335). The median number of involved nodes was 3 (range, 1-16). The local control at 1 and 2 years was 98% and 93%, respectively. The 1- and 2-year progression-free survival was 78% and 50%, respectively. Twenty percent of treatment courses were followed by acute Grade 2 gastrointestinal (GI) toxicity: diarrhea (9%) and/or nausea (14%). Two patients (3%) experienced late Grade 2 nausea. On univariate analysis, measures of disease volume such as hormone sensitivity (p = 0.03), increasing involved node number (p = 0.008), and abdominal treatment (p = 0.03) were significantly associated with GI toxicity.

Conclusions

With the widespread adoption of PSMA agents, NORs are likely to increase. The optimal combination of local and systemic therapy in this population is unknown. With a favorable toxicity profile, IF-SBRT represents a safe and convenient local therapy treatment option for an elderly patient population. Patient- and treatment-related factors such as a large number of involved nodes and/or abdominal treatment may be associated with an increased risk of GI toxicity.

Generating synthetic computed tomography for radiotherapy: SynthRAD2023 challenge report

Radiation therapy plays a crucial role in cancer treatment, necessitating precise delivery of radiation to tumors while sparing healthy tissues over multiple days. Computed tomography (CT) is integral for treatment planning, offering electron density data crucial for accurate dose calculations. However, accurately representing patient anatomy is challenging, especially in adaptive radiotherapy, where CT is not acquired daily. Magnetic resonance imaging (MRI) provides superior soft-tissue contrast. Still, it lacks electron density information, while cone beam CT (CBCT) lacks direct electron density calibration and is mainly used for patient positioning. Adopting MRI-only or CBCT-based adaptive radiotherapy eliminates the need for CT planning but presents challenges. Synthetic CT (sCT) generation techniques aim to address these challenges by using image synthesis to bridge the gap between MRI, CBCT, and CT. The SynthRAD2023 challenge was organized to compare synthetic CT generation methods using multi-center ground truth data from 1080 patients, divided into two tasks: (1) MRI-to-CT and (2) CBCT-to-CT. The evaluation included image similarity and dose-based metrics from proton and photon plans. The challenge attracted significant participation, with 617 registrations and 22/17 valid submissions for tasks 1/2. Top-performing teams achieved high structural similarity indices (≥0.87/0.90) and gamma pass rates for photon (≥98.1%/99.0%) and proton (≥97.3%/97.0%) plans. However, no significant correlation was found between image similarity metrics and dose accuracy, emphasizing the need for dose evaluation when assessing the clinical applicability of sCT. SynthRAD2023 facilitated the investigation and benchmarking of sCT generation techniques, providing insights for developing MRI-only and CBCT-based adaptive radiotherapy. It showcased the growing capacity of deep learning to produce high-quality sCT, reducing reliance on conventional CT for treatment planning.

Whole pelvis vs. hemi pelvis elective nodal radiotherapy in patients with PSMA-positive nodal recurrence after radical prostatectomy - a retrospective multi-institutional propensity score analysis

PURPOSE

Despite growing evidence for bilateral pelvic radiotherapy (whole pelvis RT, WPRT) there is almost no data on unilateral RT (hemi pelvis RT, HPRT) in patients with nodal recurrent prostate cancer after prostatectomy. Nevertheless, in clinical practice HPRT is sometimes used with the intention to reduce side effects compared to WPRT. Prostate-specific membrane antigen positron emission tomography / computed tomography (PSMA-PET/CT) is currently the best imaging modality in this clinical situation. This analysis compares PSMA-PET/CT based WPRT and HPRT.

METHODS

A propensity score matching was performed in a multi-institutional retrospective dataset of 273 patients treated with pelvic RT due to nodal recurrence (214 WPRT, 59 HPRT). In total, 102 patients (51 in each group) were included in the final analysis. Biochemical recurrence-free survival (BRFS) defined as prostate specific antigen (PSA) < post-RT nadir + 0.2ng/ml, metastasis-free survival (MFS) and nodal recurrence-free survival (NRFS) were calculated using the Kaplan-Meier method and compared using the log rank test.

RESULTS

Median follow-up was 29 months. After propensity matching, both groups were mostly well balanced. However, in the WPRT group there were still significantly more patients with additional local recurrences and biochemical persistence after prostatectomy. There were no significant differences between both groups in BRFS (p = .97), MFS (p = .43) and NRFS (p = .43). After two years, BRFS, MFS and NRFS were 61%, 86% and 88% in the WPRT group and 57%, 90% and 82% in the HPRT group, respectively. Application of a boost to lymph node metastases, a higher RT dose to the lymphatic pathways (> 50 Gy EQD2α/β=1.5 Gy) and concomitant androgen deprivation therapy (ADT) were significantly associated with longer BRFS in uni- and multivariate analysis.

CONCLUSIONS

Overall, this analysis presents the outcome of HPRT in nodal recurrent prostate cancer patients and shows that it can result in a similar oncologic outcome compared to WPRT. Nevertheless, patients in the WPRT may have been at a higher risk for progression due to some persistent imbalances between the groups. Therefore, further research should prospectively evaluate which subgroups of patients are suitable for HPRT and if HPRT leads to a clinically significant reduction in toxicity.

Deep learning based clinical target volumes contouring for prostate cancer: Easy and efficient application

BACKGROUND

Radiotherapy has been crucial in prostate cancer treatment. However, manual segmentation is labor intensive and highly variable among radiation oncologists. In this study, a deep learning based automated contouring model is constructed for clinical target volumes (CTVs) of intact and postoperative prostate cancer.

METHODS

Computed tomography (CT) data sets of 197 prostate cancer patients were collected. Two auto-delineation models were built for radical radiotherapy and postoperative radiotherapy of prostate cancer respectively, and each model included CTVn for pelvic lymph nodes and CTVp for prostate tumors or prostate tumor beds.

RESULTS

In the radical radiotherapy model, the volumetric dice (VD) coefficient of CTVn calculated by AI, was higher than that of the one delineated by the junior physicians (0.85 vs. 0.82, p = 0.018); In the postoperative radiotherapy model, the quantitative parameter of CTVn and CTVp, counted by AI, was better than that of the junior physicians. The median delineation time for AI was 0.23 min in the postoperative model and 0.26 min in the radical model, which were significantly shorter than those of the physicians (50.40 and 45.43 min, respectively, p < 0.001). The correction time of the senior physician for AI was much shorter compared with that for the junior physicians in both models (p < 0.001).

CONCLUSION

Using deep learning and attention mechanism, a highly consistent and time-saving contouring model was built for CTVs of pelvic lymph nodes and prostate tumors or prostate tumor beds for prostate cancer, which also might be a good approach to train junior radiation oncologists.

Prognostic impact of prostate-specific membrane antigen positron emission tomography (PSMA PET) staging for clinically node-positive prostate cancer

INTRODUCTION

In the current American Joint Committee on Cancer staging system, patients with pelvic nodal metastases are considered stage IV prostate cancer. This study aims to investigate whether men with prostate-specific membrane antigen positron emission tomography (PSMA PET)-detected pelvic node-positive prostate cancer at diagnosis have a better outcome compared to men with node-positive disease identified on conventional imaging.

METHODS

This is a retrospective cohort study comparing the outcomes of men with node-positive prostate cancer and disease confined to the pelvis, staged with conventional versus PSMA PET imaging. Men had to be treated definitively with a combination of androgen deprivation therapy and radiation treatment to the prostate and pelvic lymph nodes. Kaplan-Meier and Cox regression analysis was used to compare biochemical failure-free survival (BFFS) and overall survival (OS).

RESULTS

Seventy-six men with nodal metastases confined to the pelvis were identified. Fifty-one were detected with PSMA PET while 25 were staged with conventional imaging. PSMA PET staged patients had a lower proportion of Gleason 8-10 disease (78% vs. 96%) as well as a lower median prostate-specific antigen (11 ng/mL vs. 26 ng/mL). BFFS at 4 years was 72% with PSMA PET-detected node-positive disease vs. 38% with conventionally detected node-positive disease. Four-year OS was 93% with PSMA PET staged patients vs. 76% with conventionally staged patients. On multivariate analysis, the PSMA PET staged group was associated with improved BFFS (Adjusted HR = 3.00, 95% CI 1.43, 6.29, P = 0.004) and OS (Adjusted HR = 5.81, 95% CI 1.43, 23.7, P = 0.007).

CONCLUSION

Men with PSMA PET-detected node-positive prostate cancer confined to the pelvis have significantly better biochemical control and survival compared to those with node-positive pelvic disease identified through conventional staging.

Moderately hypofractionated prostate-only versus whole-pelvis radiotherapy for high-risk prostate cancer: A retrospective real-world single-center cohort study

Background

The benefit of prophylactic whole pelvis radiation therapy (WPRT) in prostate cancer has been debated for decades, with evidence based mainly on conventional fractionation targeting pelvic nodes.

Aim

This retrospective cohort study aimed to explore the impact of adding moderately hypofractionated pelvic radiotherapy to prostate-only irradiation (PORT) on prognosis, toxicity, and quality of life in real-world settings.

Materials and methods

Patients with high-risk and conventionally staged prostate cancer (cT1-3N0M0) treated with moderately hypofractionated WPRT or PORT, using external beam radiotherapy alone or combined with high-dose-rate brachytherapy, at Örebro University Hospital between 2008 and 2021 were identified. Biochemical failure-free survival (BFFS), metastasis-free survival (MFS), prostate cancer-specific survival (PCSS), and overall survival (OS) were compared using Kaplan-Meier method and Cox proportional hazards. Toxicity and quality of life measures were also analysed.

Results

Among 516 patients (227 PORT, 289 WPRT), 5-year BFFS rates were 77 % (PORT) and 74 % (WPRT), adjusted HR=1.50 (95 % CI=0.88-2.55). No significant differences were found in MFS, PCSS, or OS in main analyses. WPRT was associated with a higher risk of acute grade ≥ 2 and 3 genitourinary toxicities whereas no differences in late toxicities or quality of life between PORT and WPRT were observed.

Conclusion

We found no significant differences in oncological outcomes or quality of life when comparing moderately hypofractionated PORT to WPRT. Some differences in toxicity patterns were observed. Despite caveats related to study design, our findings support the need for further research on WPRT's impact on treatment-related and patient-reported outcomes.

[Moderately hypofractionated dose escalation radiotherapy for localized prostate cancer, ESHYPRO: Results of a retrospective single-centre series evaluating safety and efficacy]

PURPOSE

Prostate cancer is the most frequent cancer among men and radiotherapy hypofractionation regimens have become standard treatments for the localized stages, but the absence of increased risk of acute and late genitourinary or gastrointestinal toxicity of the dose escalation still must be demonstrated.

MATERIAL AND METHODS

The study population included all patients with localized prostatic adenocarcinoma treated at the institut Curie from February 2016 to March 2018 by external radiation delivered by a linear accelerator using an image-guided conformal intensity modulation technique at a total dose of 75Gy in 30 fractions of 2.5Gy in the planning target volume that included the prostate and the proximal seminal vesicles, and could be paired with a prophylactic lymph node radiotherapy at 46Gy in 23 fractions with simultaneous integrated boost.

RESULTS

A total of 166 patients were included. Among them, 68.6% were unfavourable intermediate or (very) high risk. The median age and follow-up were 71.4years and 3.96years. One hundred and forty-nine patients received prophylactic lymph node radiotherapy (89.8%). One hundred and thirty-one patients received hormonotherapy (78.9%). Genito-urinary toxicity events of grades 2 or above during radiotherapy, at 6months, 1year and 5years were respectively 36.7%, 8.8%, 3.1% and 4.7%. Two patients had late grade 4 toxicity at 5years (1.6%). Grade 2 gastrointestinal toxicity events during radiotherapy, 6months, 1year and 5years were respectively 15.1%, 1.9%, 14.6% and 9.3%. Of these, eight patients had grade 3 toxicity (6.2%). There was no grade 4 toxicity. Analyses did not reveal any predictive factor for toxicity. The 5-year overall, progression-free, and specific survival rates were respectively 82.4%, 85.7%, and 93.3%. Serum prostate specific antigen concentration and cardiovascular risk factors were found to be predictive factors of deterioration in overall survival (P=0.0028 for both).

CONCLUSION

External radiotherapy for localized prostatic cancer with our moderately hypofractionated dose escalation regimen is well tolerated. In the absence of increased late toxicity, the analysis of the modes of long-term relapses will be interesting to determine the benefit of this dose escalation on local and distant relapses.

In Silico Comparison of Three Different Beam Arrangements for Intensity-Modulated Proton Therapy for Postoperative Whole Pelvic Irradiation of Prostate Cancer

Background and purpose: Proton therapy has been shown to provide dosimetric benefits in comparison with IMRT when treating prostate cancer with whole pelvis radiation; however, the optimal proton beam arrangement has yet to be established. The aim of this study was to evaluate three different intensity-modulated proton therapy (IMPT) beam arrangements when treating the prostate bed and pelvis in the postoperative setting. Materials and Methods: Twenty-three post-prostatectomy patients were planned using three different beam arrangements: two-field (IMPT2B) (opposed laterals), three-field (IMPT3B) (opposed laterals inferiorly matched to a posterior-anterior beam superiorly), and four-field (IMPT4B) (opposed laterals inferiorly matched to two posterior oblique beams superiorly) arrangements. The prescription was 50 Gy radiobiological equivalent (GyE) to the pelvis and 70 GyE to the prostate bed. Comparisons were made using paired two-sided Wilcoxon signed-rank tests. Results: CTV coverages were met for all IMPT plans, with 99% of CTVs receiving ≥ 100% of prescription doses. All organ at risk (OAR) objectives were met with IMPT3B and IMPT4B plans, while several rectum objectives were exceeded by IMPT2B plans. IMPT4B provided the lowest doses to OARs for the majority of analyzed outcomes, with significantly lower doses than IMPT2B +/- IMPT3B for bladder V30-V50 and mean dose; bowel V15-V45 and mean dose; sigmoid maximum dose; rectum V40-V72.1, maximum dose, and mean dose; femoral head V37-40 and maximum dose; bone V40 and mean dose; penile bulb mean dose; and skin maximum dose. Conclusion: This study is the first to compare proton beam arrangements when treating the prostate bed and pelvis. four-field plans provided better sparing of the bladder, bowel, and rectum than 2- and three-field plans. The data presented herein may help inform the future delivery of whole pelvis IMPT for prostate cancer.

Pelvic lymph node mapping in prostate cancer: examining the impact of PSMA PET/CT on radiotherapy decision-making in patients with node-positive disease

INTRODUCTION

Prostate Specific Membrane Antigen (PSMA) imaging with Positron Emission Tomography (PET) plays a crucial role in prostate cancer management. However, there is a lack of comprehensive data on how PSMA PET/CT (Computed Tomography) influences radiotherapeutic decisions, particularly in node-positive prostate cancer cases. This study aims to address this gap by evaluating two primary objectives: (1) Mapping the regional and non-regional lymph nodes (LNs) up to the aortic bifurcation and their distribution using conventional methods with CT compared to PSMA PET/CT, and (2) assessing the impact of PSMA PET/CT findings on radiotherapeutic decisions.

METHODS

A retrospective analysis of 95 node-positive prostate cancer patients who underwent both CT and PSMA PET/CT imaging prior to primary radiotherapy and androgen deprivation therapy (ADT) was conducted. The analysis focused on identifying LNs in various regions including the common iliac, external iliac, internal iliac, obturator, presacral, mesorectal, inguinal, and other stations. Treatment plans were reviewed for modifications based on PSMA PET/CT findings, and statistical analysis was performed to identify predictors for exclusive nodal positivity on PSMA PET/CT scans.

RESULTS

PSMA PET/CT identified additional positive nodes in 48% of cases, resulting in a staging shift from N0 to N1 in 29% of patients. The most frequent metastatic LNs were located in the external iliac (76 LNs; 34%), internal iliac (43 LNs; 19%), and common iliac (35 LNs; 15%) stations. In patients with nodes only detected on PSMA PET the most common nodes were in the external iliac (27, 40%), internal iliac (13, 19%), obturator (11, 15%) stations. Within the subgroup of 28 patients exclusively demonstrating PSMA PET-detected nodes, changes in radiotherapy treatment fields were implemented in 5 cases (18%), and a dose boost was applied for 23 patients (83%). However, no discernible predictors for exclusive nodal positivity on PSMA PET/CT scans emerged from the analysis.

DISCUSSION

The study underscores the pivotal role of PSMA PET/CT compared to CT alone in accurately staging node-positive prostate cancer and guiding personalized radiotherapy strategies. The routine integration of PSMA PET/CT into diagnostic protocols is advocated to optimize treatment precision and improve patient outcomes.

Patterns of Failure After Prostate-Only Radiotherapy in High-Risk Prostate Cancer: Implications for Refining Pelvic Nodal Contouring Guidelines

PURPOSE

To study prostate specific membrane antigen - positron emission tomography (Ga68PSMA-PETCT) based patterns of relapse at biochemical failure (BCF) after prostate-only radiotherapy (PORT) in high-risk (HR) prostate cancer and its implications on pelvic contouring recommendations.

METHODS AND MATERIALS

Patients with clinico-radiological high-risk node-negative prostate cancer treated with curative PORT and androgen deprivation therapy (ADT), either within the POP-RT randomised trial or off trial, who underwent a Ga68PSMA-PETCT upon BCF were included. Patterns of regional and distant recurrence on Ga68PSMA-PETCT were studied. Pelvic nodal recurrences were mapped with reference to the superior border of pubic symphysis. Pelvic lymph nodal caudal border (PLNcb) recommendations in the published contouring guidelines (RTOGcb, GETUGcb, PIVOTALcb, NRGcb, GFRUcb) were evaluated.

RESULTS

Of the total 262 patients screened, 68 eligible patients were included (POP-RT trial 35 patients; off-trial 33 patients). Median follow-up was 91 months (IQR, 72-117) and median time to BCF was 65 months (IQR, 49-83). Regional and distant recurrence was seen in 31 (46%) and 31 (46%) patients, respectively. Of the nodal recurrences, nearly half (46%, 14/31) had no distant metastases and 64% (20/31) had a failure in the common iliac nodal region. The lower-most nodal recurrence was 20 mm cranial to the top of pubic symphysis (RTOGcb, GETUGcb, GFRUcb) and 10 mm cranial to the PIVOTALcb. The PLNcb recommended by NRG guideline (NRGcb) had an inter-patient variability of 32 mm, ranging from 16 mm above to 16 mm below the top of pubic symphysis, and the lower most nodal recurrence ranged from 4 mm to 36 mm cranial to NRGcb.

CONCLUSION

Pelvic failures accounted for a major proportion of recurrences after prostate-only radiotherapy, with the caudal most nodal recurrence being 20 mm cranial to the top of pubic symphysis. This could have implications in defining the caudal border of contouring recommendations.

Impact of Prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography on Prostate Cancer Salvage Radiotherapy Management: Results from a Prospective Multicenter Randomized Phase 3 Trial (PSMA-SRT NCT03582774)

BACKGROUND AND OBJECTIVE

Both imaging and several prognostic factors inform the planning of salvage radiotherapy (SRT). Prostate-specific membrane antigen positron emission tomography (PSMA-PET) can localize disease unseen by other imaging modalities. The main objective of the study was to evaluate the impact of PSMA-PET on biochemical recurrence-free survival rate after SRT.

METHODS

This prospective randomized, controlled, phase 3 clinical trial randomized 193 patients with biochemical recurrence of prostate cancer after radical prostatectomy to proceed with SRT (control arm, n = 90) or undergo a PSMA-PET/computed tomography (CT) scan prior to SRT planning (investigational arm, n = 103) from June 2018 to August 2020. Any other approved imaging modalities were allowed in both arms (including fluciclovine-PET). This is a secondary endpoint analysis: impact of PSMA-PET on SRT planning. Case-report forms were sent to referring radiation oncologists to collect the management plans before randomization and after completion of SRT. The relative frequency (%) of management changes within each arm were compared using chi-square and Fisher's exact tests.

KEY FINDINGS AND LIMITATIONS

The delivered SRT plan was available in 178/193 patients (92.2%;76/90 control [84.4%] and 102/103 PSMA-PET [99%]). Median prostate-specific antigen levels at enrollment was 0.30 ng/ml (interquartile range [IQR] 0.19-0.91) in the control arm and 0.23 ng/ml (IQR 0.15-0.54) in the PSMA-PET arm. Fluciclovine-PET was used in 33/76 (43%) in the control arm. PSMA-PET localized recurrence(s) in 38/102 (37%): nine of 102 (9%) outside of the pelvis (M1), 16/102 (16%) in the pelvic LNs (N1, with or without local recurrence), and 13/102 (13%) in the prostate fossa only. There was a 23% difference (95% confidence interval [CI] 9-35%, p = 0.002) of frequency of major changes between the control arm (22% [17/76]) and the PSMA-PET intervention arm (45%[46/102]). Of the major changes in the intervention group, 33/46 (72%) were deemed related to PSMA-PET. There was a 17.6% difference (95% CI 5.4-28.5%, p = 0.005) of treatment escalation frequency between the control arm (nine of 76 [12%]) and the intervention arm (30/102 [29%]). Treatment de-escalation occurred in the control and intervention arms in eight of 76 (10.5%) and 12/102 (11.8%) patients, and mixed changes in zero of 76 (0%) and four of 102 (3.9%) patients, respectively.

CONCLUSIONS AND CLINICAL IMPLICATIONS

In this prospective randomized phase 3 study, PSMA-PET findings provided information that initiated major management changes to SRT planning in 33/102 (33%) patients. The final readout of the primary endpoint planned in 2025 may provide evidence on whether these changes result in improved outcomes.

PATIENT SUMMARY

Prostate-specific membrane antigen positron emission tomography leads to management changes in one-third of patients receiving salvage radiotherapy for post-radical prostatectomy biochemical recurrence of prostate cancer.

Delayed tumor-draining lymph node irradiation preserves the efficacy of combined radiotherapy and immune checkpoint blockade in models of metastatic disease

Cancer resistance to immune checkpoint inhibitors motivated investigations into leveraging the immunostimulatory properties of radiotherapy to overcome immune evasion and to improve treatment response. However, clinical benefits of radiotherapy-immunotherapy combinations have been modest. Routine concomitant tumor-draining lymph node irradiation (DLN IR) might be the culprit. As crucial sites for generating anti-tumor immunity, DLNs are indispensable for the in situ vaccination effect of radiotherapy. Simultaneously, DLN sparing is often not feasible due to metastatic spread. Using murine models of metastatic disease in female mice, here we demonstrate that delayed (adjuvant), but not neoadjuvant, DLN IR overcomes the detrimental effect of concomitant DLN IR on the efficacy of radio-immunotherapy. Moreover, we identify IR-induced disruption of the CCR7-CCL19/CCL21 homing axis as a key mechanism for the detrimental effect of DLN IR. Our study proposes delayed DLN IR as a strategy to maximize the efficacy of radio-immunotherapy across different tumor types and disease stages.

Moderate hypofractionated radiotherapy to the prostate bed with or without pelvic lymph nodes: a prospective trial

Background

Hypofractionated radiotherapy in the treatment of prostate cancer has been widely studied. However, in the postoperative setting it has been less explored. The objective of this prospective study is to evaluate the safety and efficacy of hypofractionated radiotherapy in postoperative prostate cancer.

Materials and methods

A prospective study was designed to include patients with prostate cancer with an indication of postoperative radiotherapy as adjuvant or salvage. A hypofractionated radiotherapy scheme of 51 Gy in 17 fractions was performed with the possibility of treating the pelvis at a dose of 36 Gy in 12 fractions sequentially. Safety was evaluated based on acute and late toxicity [according to the Radiation Therapy Oncology Group (RTOG) scale and Common Terminology Criteria Adverse Events (CTCAE) v4.03], International Prognostic Scoring System (IPSS) over time, and quality of life.

Results

From August 2020 to June 2022, 31 patients completed treatment and were included in this report. 35.5% of patients received elective treatment of the pelvic nodal areas. Most patients reported minimal or low acute toxicity, with an acute gastrointestinal (GI) and genitourinary (GU) grade 3 or greater toxicity of 3.2% and 0%, respectively. The evolution in time of the IPSS remained without significant differences (p = 0.42). With the exception of a significant improvement in the domains of hormonal and sexual symptoms of the Expanded Prostate Cancer Index Composite (EPIC) questionnaire, the rest of the domains [EPIC, European Organization for Research and Treatment of Cancer (EORTC) Core quality of life questionnaire (C-30) and Prostate Cancer module (PR-25)] were maintained without significant differences over time. With a follow-up of 15.4 months, late GI and GU grade 2 toxicity was reported greater than 0% and 9.6%, respectively.

Conclusions

Hypofractionated radiotherapy in postoperative prostate cancer appears to be safe with low reports of relevant acute or late toxicity. Further follow-up is required to confirm these results.

Trial registration

The protocol was approved by the accredited Medical Ethical Committee of Pontificia Universidad Católica de Chile. All participants accepted and wrote informed consent.

European association of urology risk stratification predicts outcome in patients receiving PSMA-PET-planned salvage radiotherapy for biochemical recurrence following radical prostatectomy

PURPOSE

The European Association of Urology (EAU) proposed a risk stratification (high vs. low risk) for patients with biochemical recurrence (BR) following radical prostatectomy (RP). Here we investigated whether this stratification accurately predicts outcome, particularly in patients staged with PSMA-PET.

METHODS

For this study, we used a retrospective database including 1222 PSMA-PET-staged prostate cancer patients who were treated with salvage radiotherapy (SRT) for BR, at 11 centers in 5 countries. Patients with lymph node metastases (pN1 or cN1) or unclear EAU risk group were excluded. The remaining cohort comprised 526 patients, including 132 low-risk and 394 high-risk patients.

RESULTS

The median follow-up time after SRT was 31.0 months. The 3-year biochemical progression-free survival (BPFS) was 85.7 % in EAU low-risk versus 69.4 % in high-risk patients (p = 0.002). The 3-year metastasis-free survival (MFS) was 94.4 % in low-risk versus 87.6 % in high-risk patients (p = 0.005). The 3-year overall survival (OS) was 99.0 % in low-risk versus 99.6 % in high-risk patients (p = 0.925). In multivariate analysis, EAU risk group remained a statistically significant predictor of BPFS (p = 0.003, HR 2.022, 95 % CI 1.262-3.239) and MFS (p = 0.013, HR 2.986, 95 % CI 1.262-7.058).

CONCLUSION

Our data support the EAU risk group definition. EAU risk grouping for BCR reliably predicted outcome in patients staged lymph node-negative after RP and with PSMA-PET before SRT. To our knowledge, this is the first study validating the EAU risk grouping in patients treated with PSMA-PET-planned SRT.

Hypofractionated radiation therapy combined with androgen deprivation therapy for high-risk localized prostate cancer

INTRODUCTION

This study aimed to analyse the treatment outcomes of moderately hypofractionated radiation therapy (RT) combined with androgen deprivation therapy (ADT) and the prognostic implications of prostate-specific antigen (PSA) kinetics in high-risk localized prostate cancer.

METHODS

The medical records of 140 patients who underwent definitive RT (70 Gy in 28 fractions) combined with ADT were retrospectively reviewed. ADT consists of a gonadotropin-releasing hormone agonist and an anti-androgen. Clinical outcomes included the biochemical failure rate (BFR), clinical failure rate (CFR), overall survival (OS) and prostate cancer-specific survival (PCSS). The BFR and CFR were stratified by the PSA nadir and the time to the PSA nadir, respectively. Acute and late genitourinary and gastrointestinal adverse events were also recorded.

RESULTS

The 5-year BFR, CFR, OS and PCSS rates were 9.8%, 4.5%, 90.2% and 98.7%, respectively. Ninety-five (67.9%) patients achieved a PSA nadir of 0.01 ng/mL. Patients with a PSA nadir >0.01 ng/mL had a significantly higher BFR and CFR (BFR, P = 0.001; CFR, P = 0.027), even after adjusting for other prognostic factors [per 0.1 ng/mL; BFR, hazard ratio (HR) 4.440, P < 0.001; CFR, HR 4.338, P = 0.001]. However, the time to the PSA nadir and pre-RT PSA were not significantly associated with the BFR and CFR. Six patients (4.3%) reported grade 3 late adverse events, mostly haematuria and haematochezia.

CONCLUSION

Definitive RT with moderate hypofractionation combined with long-term ADT showed good efficacy for high-risk localized prostate cancer. The lowest PSA nadir was significantly associated with a low recurrence rate, indicating the importance of PSA follow-up.

Pelvic Irradiation for Node-Positive Prostate Cancer After Prostatectomy: Long-Term Results of the Prospective PLATIN-4 and PLATIN-5 Trials

PURPOSE

After radical prostatectomy (RP), adjuvant or salvage radiation treatment in node-positive prostate cancer is offered to prevent systemic disease. Prospective long-term survival and toxicity data on patients with radiation for nodal disease are still scarce. This study evaluates safety and feasibility of salvage radiation therapy to the pelvic lymph nodes in node-positive prostate cancer after RP.

METHODS AND MATERIALS

Between 2009 and 2018, 78 patients with lymph node recurrence after RP (PLATIN-4 trial) or after RP and prostate bed radiation therapy (PLATIN-5 trial) were treated with salvage pelvic lymph node radiation therapy with boost to the involved nodes as field abutment (PLATIN-5) and boost to the prostate bed (PLATIN-4). Androgen deprivation therapy was started 2 months before radiation and recommended for 24 months. The primary endpoint was safety and feasibility of the intensity modulated radiation therapy-image guided radiation therapy technique based on the rate of treatment discontinuations and incidence of Common Terminology Criteria for Adverse Events grade 3+ toxicity. Secondary endpoints were progression-free survival and overall survival.

RESULTS

No treatment discontinuations were reported in either trial. Median overall survival was not reached in PLATIN-4 and was 117 months in PLATIN-5. Median progression-free survival was 66 months in PLATIN-4 and 39 months in PLATIN-5. Late grade 3+ genitourinary and gastrointestinal toxicities were observed in 4% of patients at 24 months of follow-up.

CONCLUSIONS

Salvage radiation therapy to the prostate bed and pelvic lymphatic drainage combined with long-term androgen deprivation therapy is a curative treatment option for patients with node-positive prostate cancer after RP, with excellent in-field disease control. Pelvic lymph node radiation therapy as field abutment after prostate bed radiation therapy is feasible with long-term survival and no high-grade toxicity.

Safety of Ultrahypofractionated Pelvic Nodal Irradiation in the Definitive Management of Prostate Cancer: Systematic Review and Meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to evaluate the evidence for ultrahypofractionated pelvic nodal irradiation in patients with prostate cancer, with a focus on reported acute and late toxicities.

METHODS AND MATERIALS

A comprehensive search was conducted in 5 electronic databases (PubMed, Scopus, Web of Science, Cochrane Library, ClinicalTrials.gov) from inception until March 23, 2023. Eligible publications included patients with intermediate- and high-risk and node-positive prostate cancer who underwent elective or therapeutic ultrahypofractionated pelvic nodal irradiation. Primary outcomes included the presence of grade ≥2 rates of acute and late gastrointestinal and genitourinary toxicity based on the Common Terminology Criteria for Adverse Events or Radiation Therapy Oncology Group scales. Quality assessment was performed using National Institutes of Health tools for noncontrolled beforeand after (single arm) clinical trials, as well as single-arm observational studies. Because all outcomes were categorical variables, proportion was calculated to estimate the effect size and compare the outcomes after the intervention.

RESULTS

We identified 16 publications that reported the use of ultrahypofractionated radiation therapy to treat the pelvis in prostate cancer. Seven publications met our criteria and were included in the meta-analysis, including 417 patients. The median total dose to the pelvic lymph nodes was 25 Gy (range, 25-28.5 Gy), with a median of 5 fractions. The prostate received a median dose of 40 Gy (range, 35-47.5 Gy). All studies used androgen deprivation therapy for a median duration of 18 months. The median follow-up period was 3 years (range, 0.5-5.6 years). The rates of acute grade ≥2 gastrointestinal and genitourinary toxicity were 8% (95% CI, 1%-15%) and 29% (95% CI, 18%-41%), respectively. For late grade ≥2 gastrointestinal and genitourinary toxicity, the rates were 13% (95% CI, 5%-21%) and 29% (95% CI, 17%-42%), respectively.

CONCLUSIONS

Ultrahypofractionated pelvic nodal irradiation appears to be a safe approach in terms of acute and late genitourinary and gastrointestinal toxicity.

Assessing the toxicity after moderately hypofractionated prostate and whole pelvis radiotherapy compared to conventional fractionation

OBJECTIVE

To evaluate acute and late gastrointestinal (GI) and genitourinary (GU) toxicities after moderately hypofractionated (HF) or conventionally fractionated (CF) primary whole-pelvis radiotherapy (WPRT).

METHODS

Primary prostate-cancer patients treated between 2009 and 2021 with either 60 Gy at 3 Gy/fraction to the prostate and 46 Gy at 2.3 Gy/fraction to the whole pelvis (HF), or 78 Gy at 2 Gy/fraction to the prostate and 50/50.4 Gy at 1.8-2 Gy/fraction to the whole pelvis (CF). Acute and late GI and GU toxicities were retrospectively assessed.

RESULTS

106 patients received HF and 157 received CF, with a median follow-up of 12 and 57 months. Acute GI toxicity rates in the HF and CF groups were, respectively, grade 2: 46.7% vs. 37.6%, and grade 3: 0% vs. 1.3%, with no significant difference (p = 0.71). Acute GU toxicity rates were, respectively, grade 2: 20.0% vs. 31.8%, and grade 3: 2.9% vs. 0%, (p = 0.04). We compared prevalence of late GI and GU toxicities between groups after 3, 12, and 24 months and did not find any significant differences (respectively, p = 0.59, 0.22, and 0.71 for GI toxicity; p = 0.39, 0.58, and 0.90 for GU toxicity).

CONCLUSION

Moderate HF WPRT was well tolerated during the first 2 years. Randomized trials are needed to confirm these findings.

Artificial Intelligence-Based Autosegmentation: Advantages in Delineation, Absorbed Dose-Distribution, and Logistics

Purpose

The study's purpose was to compare the performance of artificial intelligence (AI) in auto-contouring compared with a human practitioner in terms of precision, differences in dose distribution, and time consumption.

Methods and Materials

Datasets of previously irradiated patients in 3 different segments (head and neck, breast, and prostate cancer) were retrospectively collected. An experienced radiation oncologist (MD) performed organs-at-risk (OARs) and standard clinical target volume delineations as baseline structures for comparison. AI-based autocontours were generated in 2 additional CT copies; therefore, 3 groups were assessed: MD alone, AI alone, and AI plus MD corrections (AI+C). Differences in Dice similarity coefficient (DSC) and person-hour burden were assessed. Furthermore, changes in clinically relevant dose-volume parameters were evaluated and compared.

Results

Seventy-five previously treated cases were collected (25 per segment) for the analysis. Compared with MD contours, the mean DSC scores were higher than 0.7 for 74% and 80% of AI and AI+C, respectively. After corrections, 17.1% structures presented DSC score deviations higher than 0.1 and 10.4% dose-volume parameters significantly changed in AI-contoured structures. The time consumption assessment yielded mean person-hour reductions of 68%, 51%, and 71% for breast, prostate, and head and neck cancer, respectively.

Conclusions

In great extent, AI yielded clinically acceptable OARs and certain clinical target volumes in the explored anatomic segments. Sparse correction and assessment requirements place AI+C as a standard workflow. Minimal clinically relevant differences in OAR exposure were identified. A substantial amount of person-hours could be repurposed with this technology.

Consensus Delineation Guidelines for Pelvic Lymph Node Radiation Therapy of Prostate Cancer: On Behalf of the Francophone Group of Urological Radiation Therapy (GFRU)

PURPOSE

Clinical target volume (CTV) delineation for pelvic lymph nodes in prostate cancer is currently based on 3 consensus guidelines with some inherent discrepancies. To improve the reproducibility in nodal delineation, the Francophone Group of Urological Radiotherapy (Groupe Francophone de Radiothérapie Urologique [GFRU]) worked toward proposing an easily applicable, reproducible, and practice-validated contouring guideline for pelvic nodal CTV.

METHODS AND MATERIALS

The nodal CTV data sets of a high-risk node-negative prostate cancer clinical case contoured by 86 radiation oncologists participating in a GFRU contouring workshop were analyzed. CTV volumes were defined before and after a structured presentation of literature data on lymphatic drainage pathways and patterns of nodal involvement and relapse, illustrated using a reference contour (CRef) defined by 3 GFRU experts. The consistency between the participants' contours and CRef was assessed quantitively by means of the Simultaneous Truth and Performance Level Estimation (STAPLE) method, the Dice coefficient, and the Hausdorff distance and qualitatively using a count map. These results combined with the literature review were thoroughly discussed among GFRU experts to reach a consensus.

RESULTS

From the 86 workshop participants, the volume of the STAPLE CTV was 591 cc compared with 502 cc for CRef. The Dice coefficient of the STAPLE CTV compared with the experts' CRef was 0.736 (±0.084) before and 0.823 (±0.070) after the workshop; the standard deviation decreased from 11.5% to 8.5% over the workshop. The Hausdorff distance of the STAPLE CTV compared with the CRef was 34.5 mm (±12.4) before the workshop and 21.8 mm (±9.3) after the workshop. Four areas of significant interobserver variability were identified, and a consensus was reached.

CONCLUSIONS

Using a robust methodology, our cooperative group proposed an easily applicable, reproducible, and practice-validated guideline for the delineation of the pelvic CTV in prostate cancer, useful for implementation in daily practice and clinical trials.

Intensity modulated radiation therapy with stereotactic body radiation therapy boost for unfavorable prostate cancer: five-year outcomes

PURPOSE

Intensity-modulated radiation therapy (IMRT) with brachytherapy boost for unfavorable prostate cancer has been shown to improve biochemical relapse-free survival compared to IMRT alone. Stereotactic body radiation therapy (SBRT) is a less-invasive alternative to brachytherapy. Early outcomes utilizing SBRT boost suggest low rates of high-grade toxicity with a maintained patient-reported quality of life. Here, we report the 5-year progression-free survival (PFS) and prostate cancer-specific survival (PCSS) of patients treated with IMRT plus SBRT boost.

MATERIALS AND METHODS

Between 2008 and 2020, 255 patients with unfavorable prostate cancer were treated with robotic SBRT (19.5 Gy in three fractions) followed by fiducial-guided IMRT (45-50.4 Gy) according to an institutional protocol. For the first year, the patient's PSA level was monitored every 3 months, biannually for 2 years, and annually thereafter. Failure was defined as nadir + 2 ng/mL or a rising PSA with imaging suggestive of recurrence. Detection of recurrence also included digital rectal examination and imaging studies, such as MRI, CT, PET/CT, and/or bone scans. PFS and PCSS were calculated using the Kaplan-Meier method.

RESULTS

The median follow-up period was 71 months. According to the NCCN risk classification, 5% (13/255) of the patients had favorable intermediate-risk disease, 23% (57/255) had unfavorable intermediate-risk disease, 40% (102/255) had high-risk disease, and 32% (83/255) had very high-risk disease. Androgen deprivation therapy was administered to 80% (204/255) of the patients. Elective pelvic lymph node IMRT was performed in 28 (10%) patients. The PFS for all patients at 5 years was 81% (favorable intermediate risk, 91%; unfavorable intermediate risk, 89%; high-risk, 78%; and very-high risk, 72%). The PCSS for all patients at 5 years was 97% (favorable intermediate risk, 100%; unfavorable intermediate risk, 100%; high risk, 100%; and very high risk, 89%).

CONCLUSION

The incidence of failure following IMRT plus SBRT for unfavorable prostate cancer remains low at 5 years.

Managing postoperative biochemical relapse in prostate cancer, from the perspective of the Francophone group of Urological radiotherapy (GFRU)

Up to 50% of patients treated with radical surgery for localized prostate cancer may experience biochemical recurrence that requires appropriate management. Definitions of biochemical relapse may vary, but, in all cases, consist of an increase in a PSA without clinical or radiological signs of disease. Molecular imaging through to positron emission tomography has taken a preponderant place in relapse diagnosis, progressively replacing bone scan and CT-scan. Prostate bed radiotherapy is currently a key treatment, the action of which should be potentiated by androgen deprivation therapy. Nowadays perspectives consist in determining the best combination therapies, particularly thanks to next-generation hormone therapies, but not exclusively. Several trials are ongoing and should address these issues. We present here a literature review aiming to discuss the current management of biochemical relapse in prostate cancer after radical surgery, in lights of recent findings, as well as future perspectives.

Multi-institutional Development and Validation of Contouring Guidelines for Para-aortic Elective Nodal Irradiation in Prostate Cancer Based on Patterns of Involvement on Targeted Molecular Imaging Positron Emission Tomography/Computed Tomography

PURPOSE

Molecular imaging better identifies anatomic regions of metastatic spread of prostate cancer compared with conventional imaging, resulting in para-aortic (PA) nodal metastases being increasingly identified. Consequently, some radiation oncologists electively treat the PA lymph node region in patients with gross or high risk of PA nodal involvement. The anatomic locations of at-risk PA lymph nodes for prostate cancer are unknown. Our objective was to use molecular imaging to develop guidelines for the optimal delineation of the PA clinical target volume (CTV) in patients with prostate cancer.

METHODS AND MATERIALS

We conducted a multi-institutional retrospective cohort study of patients with prostate cancer undergoing 18F-fluciclovine or 18F-DCFPyL prostate-specific membrane antigen positron emission tomography (PET)/computed tomography (CT). Images of patients with PET-positive PA nodes were imported into the treatment planning system, avid nodes were contoured, and measurements were taken in relation to anatomic landmarks. A contouring guideline that encompassed the location of ≥95% of PET-positive PA nodes was created using descriptive statistics and then validated in an independent data set.

RESULTS

Five hundred fifty-nine patients had molecular PET/CT imaging in the development data set (78% 18F-fluciclovine, 22% prostate-specific membrane antigen). Seventy-six patients (14%) had evidence of PA nodal metastasis. We determined that expanding the CTV to 1.8 cm left of the aorta, 1.4 cm right of the inferior vena cava (IVC), 7 mm posterior to the aorta/IVC or to the vertebral body, and superiorly to the T11/T12 vertebral interface, with the anterior border 4 mm anterior to the aorta/IVC and inferior border at the bifurcation of the aorta/IVC, resulted in coverage of ≥95% of PET-positive PA nodes. When the guideline was used in the independent validation data set (246 patients with molecular PET/CT imaging, of whom 31 had PA nodal metastasis), 97% of nodes were encompassed, thereby validating our guideline.

CONCLUSIONS

We used molecular PET/CT imaging to determine the anatomic locations of PA metastases to develop contouring guidelines for creating a prostate cancer PA CTV. Although the optimal patient selection and clinical benefits of PA radiation therapy remain uncertain, our results will aid in delineating the optimal target when PA radiation therapy is pursued.

Elective Nodal Irradiation for Oligorecurrent Nodal Prostate Cancer: Interobserver Variability in the PEACE V-STORM Randomized Phase 2 Trial

Purpose

Consistency in delineation of pelvic lymph node regions for prostate cancer elective nodal radiation therapy is still challenging despite current guidelines. The aim of this study was to evaluate the interobserver variability in elective lymph node delineation in the PEACE V - STORM randomized phase 2 trial for oligorecurrent nodal prostate cancer.

Methods and Materials

Twenty-three centers were asked to delineate the elective pelvic nodal clinical target volume (CTV) of a postoperative oligorecurrent nodal prostate cancer benchmark case using a modified Radiation Therapy Oncology Group (RTOG) 2009 template (upper limit at the L4/L5 interspace). Overall, intersection and overflow volumes, Dice coefficient, Hausdorff distance, and count maps merged with computed tomography images were analyzed.

Results

The mean volume including the 23 nodal CTVs was 430.4 ± 64.1 cm3, larger than the modified RTOG 2009 CTV reference volume (386.1 cm3). The intersection common volume between the modified reference RTOG 2009 and the 23 nodal CTVs was estimated at 83.9%, whereas the overflow volume was 23.4%, mainly located at the level of the presacral and the upper limit of the L4/L5 interspace. The mean Dice coefficient was 0.79 ± 0.02, whereas the mean Hausdorff distance was 27 ± 4.4 mm.

Conclusions

In salvage radiation therapy treatment of oligorecurrent nodal prostate cancer, variations in elective lymph node volume delineation were mainly observed in the presacral and common iliac areas. Routine implementation and diffusion of available contouring guidelines together with a constant evaluation and evidence-based updating are expected to further decrease the existing variability in pelvic node contouring.

Diagnostic Performance and Safety of Positron Emission Tomography with 18F-rhPSMA-7.3 in Patients with Newly Diagnosed Unfavourable Intermediate- to Very-high-risk Prostate Cancer: Results from a Phase 3, Prospective, Multicentre Study (LIGHTHOUSE)

BACKGROUND

Radiohybrid (rh) 18F-rhPSMA-7.3 is a novel high-affinity prostate-specific membrane antigen (PSMA)-targeting radiopharmaceutical for prostate cancer (PCa) imaging.

OBJECTIVE

To evaluate the diagnostic performance and safety of 18F-rhPSMA-7.3 in newly diagnosed PCa patients planned for prostatectomy.

DESIGN, SETTING, AND PARTICIPANTS

Data on 18F-rhPSMA-7.3 were reported from the phase 3 prospective, multicentre LIGHTHOUSE study (NCT04186819).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Patients underwent positron emission tomography/computed tomography (PET/CT) 50-70 min after an injection of 296 MBq 18F-rhPSMA-7.3. Images were interpreted locally and by three blinded independent readers. The coprimary endpoints were patient-level sensitivity and specificity for the detection of pelvic lymph node (PLN) metastases, validated using histopathology at PLN dissection. Prespecified statistical thresholds (lower bounds of 95% confidence interval [CI]) were set at 22.5% for sensitivity and 82.5% for specificity.

RESULTS AND LIMITATIONS

Of 372 patients screened, 352 had evaluable 18F-rhPSMA-7.3-PET/CT and 296 (99 [33%] with unfavourable intermediate-risk [UIR] and 197 [67%] with high-/very-high-risk [VHR] PCa) subsequently underwent surgery. As per the independent reads, 23-37 (7.8-13%) patients had 18F-rhPSMA-7.3-positive PLN. Seventy (24%) patients had one or more positive PLNs on histopathology. The sensitivity for PLN detection was 30% (95% CI, 19.6-42.1%) for reader 1, 27% (95% CI, 17.2-39.1%) for reader 2, and 23% (95% CI, 13.7-34.4%) for reader 3, not meeting the prespecified threshold. Specificity was 93% (95% CI, 88.8-95.9%), 94% (95% CI, 89.8-96.6%), and 97% (95% CI, 93.7-98.7%), respectively, exceeding the threshold for all readers. Specificity was high (≥92%) across both risk stratifications. Sensitivity was higher among high-risk/VHR (24-33%) than among UIR (16-21%) patients. Extrapelvic (M1) lesions were reported for 56-98/352 (16-28%) patients who underwent 18F-rhPSMA-7.3-PET/CT irrespective of surgery. Verification of these (predominantly by conventional imaging) gave a verified detection rate of 9.9-14% (positive predictive value, 51-63%). No serious adverse events were observed.

CONCLUSIONS

Across all risk stratifications, 18F-rhPSMA-7.3-PET/CT had high specificity, meeting the specificity endpoint. The sensitivity endpoint was not met, although higher sensitivity was noted among high-risk/VHR than among UIR patients. Overall, 18F-rhPSMA-7.3-PET/CT was well tolerated, and identified N1 and M1 disease prior to surgery in newly diagnosed PCa patients.

PATIENT SUMMARY

In order to select the most appropriate treatment for patients with prostate cancer, it is critical to diagnose the disease burden accurately at initial diagnosis. In this study, we investigated a new diagnostic imaging agent in a large population of men with primary prostate cancer. We found it to have an excellent safety profile and to provide clinically useful information regarding the presence of disease beyond the prostate.

Salvage Whole-Pelvic Radiation and Long-Term Androgen-Deprivation Therapy in the Management of High-Risk Prostate Cancer: Long-Term Update of the McGill 0913 Study

PURPOSE

To report the long-term outcomes of the McGill 0913 study and the potential benefits of combining prostate-bed radiotherapy (PBRT), pelvic-lymph-node radiotherapy (PLNRT), and long term ADT (LT-ADT).

MATERIALS AND METHODS

From 2010 to 2016, 46 high-risk prostate cancer patients who experienced biochemical recurrence (BCR) after radical prostatectomy (RP) were enrolled in this single-arm phase II clinical trial. The patients were eligible if they had a Gleason score > 8, locally advanced disease (≥pT3), a preoperative PSA of >20 ng/mL, or positive lymph nodes (LN). The patients were treated with a combination of 24 months of ADT, PBRT, and PLNRT. The primary outcome was biochemical progression-free survival (bPFS) and the predefined secondary endpoints included distant-metastasis-free survival (DMFS), overall survival (OS), and toxicity. In this update, we also report the median follow-up of 8.8 years and 10 years OS.

RESULTS

At a median follow-up of 8.8 years, 43 patients were eligible for analysis. The median pre-salvage PSA was 0.30 μg/L. Half (51%) of the patients (n = 22) had positive margins, 40% (n = 17) had Gleason scores > 8, 63% (n = 27) had extracapsular extension, 42% (n = 18) had seminal vesicle invasion, and 19% (n = 8) had LN involvement. The 10-year bPFS was 68.3 %. The 10-year DMFS was 72.9%. The 10-year OS was 97%. There were two non-cancer-related deaths. The first patient died of congestive heart failure while the other died of an unknown cause. No new toxicity was observed after the initial report.

CONCLUSIONS

Our study demonstrates that treatment escalation with PBRT, PLNRT, and LT-ADT improves long term outcomes. In view of the recently published SPPORT study, we conclude that this novel approach of treatment intensification in high-risk post-prostatectomy patients is safe and effective, and that it should be offered as the standard of care.

The Sentinel Lymph Node in Treatment Planning: A Narrative Review of Lymph-Flow-Guided Radiotherapy

The sentinel lymph node technique is minimally invasive and used routinely by surgeons, reducing the need for morbid extensive lymph node dissections, which is a significant advantage for cancer staging and treatment decisions. The sentinel lymph node could also help radiation oncologists to identify tumor drainage for each of their patients, leading to a more personalized radiotherapy, instead of a probabilistic irradiation based on delineation atlases. The aim is both to avoid recurrence in unexpected areas and to limit the volume of irradiated healthy tissues. The aim of our study is to evaluate the impact of sentinel lymph node mapping for radiation oncologists. This concept, relying on sentinel lymph node mapping for treatment planning, is known as lymph-flow-guided radiotherapy. We present an up-to-date narrative literature review showing the potential applications of the sentinel lymph node technique for radiotherapy, as well as the limits that need to be addressed before its routine usage.

Salvage radiotherapy is effective in patients with PSMA-PET-negative biochemical recurrence- results of a retrospective study

BACKGROUND

/Purpose: The present study aimed to assess whether SRT to the prostatic fossa should be initiated in a timely manner after detecting biochemical recurrence (BR) in patients with prostate cancer, when no correlate was identified with prostate-specific membrane antigen positron emission tomography (PSMA-PET).

MATERIALS AND METHODS

This retrospective, multicenter analysis included 1222 patients referred for PSMA-PET after a radical prostatectomy due to BR. Exclusion criteria were: pathological lymph node metastases, prostate-specific antigen (PSA) persistence, distant or lymph node metastases, nodal irradiation, and androgen deprivation therapy (ADT). This led to a cohort of 341 patients. Biochemical progression-free survival (BPFS) was the primary study endpoint.

RESULTS

The median follow-up was 28.0 months. The 3-year BPFS was 71.6% in PET-negative cases and 80.8% in locally PET-positive cases. This difference was significant in univariate (p=0.019), but not multivariate analyses (p=0.366, HR: 1.46, 95%CI: 0.64-3.32). The 3-year BPFS in PET-negative cases was significantly influenced by age (p=0.005), initial pT3/4 (p<0.001), pathology scores (ISUP) ≥3 (p=0.026), and doses to fossa >70 Gy (p=0.027) in univariate analyses. In multivariate analyses, only age (HR: 1.096, 95%CI: 1.023-1.175, p=0.009) and PSA-doubling time (HR: 0.339, 95%CI: 0.139-0.826, p=0.017) remained significant.

CONCLUSION

To our best knowledge, this study provided the largest SRT analysis in patients without ADT that were lymph node-negative on PSMA-PET. A multivariate analysis showed no significant difference in BPFS between locally PET-positive and PET-negative cases. These results supported the current EAU recommendation to initiate SRT in a timely manner after detecting BR in PET negative patients.

Treatment-related toxicity using prostate bed versus prostate bed and pelvic lymph node radiation therapy following radical prostatectomy: A national population-based study

Purpose There is debate about the effectiveness and toxicity of pelvic lymph node (PLN) irradiation in addition to prostate bed radiotherapy when used to treat disease recurrence following radical prostatectomy. We compared toxicity from radiation therapy (RT) to the prostate bed and pelvic lymph nodes (PBPLN-RT) with prostatebed only radiation therapy (PBO-RT) following radical prostatectomy. Methods and Materials Patients with prostate cancer who underwent post-prostatectomy RT between 2010 and 2016 were identified by using the National Prostate Cancer Audit (NPCA) database. Follow-up data was available up to December 31, 2018. Validated outcome measures, based on a framework of procedural and diagnostic codes, were used to capture ≥Grade 2 gastrointestinal (GI) and genitourinary (GU) toxicity. An adjusted competing-risks regression analysis estimated subdistribution hazard ratios (sHR). A sHR > 1 indicated a higher incidence of toxicity with PBPLN-RT than with PBO-RT. Results 5-year cumulative incidences in the PBO-RT (n = 5,087) and PBPLNRT (n = 593) groups was 18.2% and 15.9% for GI toxicity, respectively. For GU toxicity it was 19.1% and 20.7%, respectively. There was no evidence of difference in GI or GU toxicity after adjustment between PBO-RT and PBPLN-RT (GI: adjusted sHR, 0.90, 95% CI, 0.67-1.19; P = 0.45); (GU: adjusted sHR, 1.19, 95% CI, 0.99-1.44; P = 0.09). Conclusions This national population-based study found that including PLNs in the radiation field following radical prostatectomy is not associated with a significant increase in rates of ≥Grade 2 GI or GU toxicity at 5 years.

Late Toxicity of Moderately Hypofractionated Intensity-Modulated Proton Therapy Treating the Prostate and Pelvic Lymph Nodes for High-Risk Prostate Cancer

PURPOSE

To evaluate late gastrointestinal (GI) and genitourinary (GU) toxicity of moderately hypofractionated intensity modulated proton therapy (IMPT) targeting the prostate and pelvic lymph nodes.

METHODS AND MATERIALS

A target accrual of 56 patients with high-risk or unfavorable intermediate risk prostate cancer were enrolled into a prospective study (ClinicalTrials.gov: NCT02874014) of moderately hypofractionated IMPT. IMPT with pencil beam scanning was used to deliver 6750 and 4500 cGy relative biological effectiveness in 25 daily fractions simultaneously to the prostate and pelvic lymph nodes, respectively. All received androgen deprivation therapy. Late GI and GU toxicity was prospectively assessed using Common Terminology Criteria for Adverse Events version 4.0, at baseline, weekly during radiation therapy, 3-month postradiation therapy, and then every 6 months. Actuarial rates of late GI and GU toxicity were estimated using Kaplan-Meier method.

RESULTS

Median age was 75.5 years. Fifty-four patients were available for late toxicity evaluation. Median follow-up was 43.9 months (range, 16-66). The actuarial rate of late grade ≥2 GI toxicity at both 2 and 3 years was 7.4% (95% confidence interval [CI], 0.2%-14.2%). The actuarial rate of late grade 3 GI toxicity at both 2 and 3 years was 1.9% (95% CI, 0%-5.4%). One patient experienced grade 3 GI toxicity with proctitis. The actuarial rate of late grade ≥2 GU toxicity was 20.5% (95% CI, 8.9%-30.6%) at 2 years, and 29.2 % (95% CI, 15.5%-40.7%) at 3 years. None had grade 3 GU toxicity. The presence of baseline GU symptoms was associated with a higher likelihood of experiencing late grade 2 GU toxicity.

CONCLUSIONS

A moderately hypofractionated IMPT targeting the prostate and regional pelvic lymph nodes was generally well tolerated. Patients with pre-existing GU symptoms had a higher rate of late grade 2 GU toxicity. A phase 3 study is needed to assess any therapeutic gain of IMPT, in comparison with photon-based radiation therapy.

Comparison of Hormone-Sensitive Oligorecurrent Prostate Cancer Patients Based on Routine Use of Choline and/or PSMA PET/CT to Guide Metastasis-Directed Therapy

BACKGROUND

In hormone-sensitive oligorecurrent prostate cancer (PC), the literature showed [68Ga]Ga-PSMA (PSMA) and [18F]F-choline (FCH) PET/CT can successfully guide metastasis-directed therapies (MDT). This observational retrospective study aimed to explore, in routine use, the impact of FCH or PSMA PET/CT in guiding MDT for hormone-sensitive oligometastatic PC at different recurrences.

METHODS

In 2017-2020, patients initially treated with radical prostatectomy but, in biochemical recurrence (with PSA ≤ 2 ng/mL), diagnosed as oligometastatic based on FCH or PSMA PET/CT, were identified. MDT was stereotactic body radiotherapy (SBRT), elective nodal or prostate bed radiotherapy ± boost and ± androgen deprivation therapy (ADT). The primary endpoint was biochemical relapse-free survival (BR-FS), defined as a PSA increase ≥ 0.2 ng/mL above the nadir and increasing over two successive samples and the secondaries were ADT-free survival (ADT-FS).

RESULTS

123 patients (70 PSMA and 53 FCH) were included. The median follow-up was 42.2 months. The median BR-FS was 24.7 months in the PSMA group versus 13.0 months in the FCH group (p = 0.008). Similarly, ADT-FS (p = 0.001) was longer in patients in the PSMA group. In multivariate analysis, a short PSA doubling time before imaging (p = 0.005) and MDT with SBRT (p = 0.001) were poor prognostic factors for BR-FS.

CONCLUSIONS

Routine use of FCH or PSMA PET/CT in hormone-sensitive PC showed an advantage for using PSMA PET/CT to guide MDT in terms of BR-FS and ADT-FS in patients with low PSA value. Prospective studies are needed to confirm these hypotheses.

Utilizing clinical, pathological and radiological information to guide postoperative radiotherapy in prostate cancer

INTRODUCTION

A detectable and rising PSA following radical prostatectomy is indicative of recurrent prostate cancer. Salvage radiotherapy (SRT) with/without androgen deprivation therapy represents the main treatment option for these patients and has been historically associated with a biochemical control rate of ~70%. To determine the optimal timing, diagnostic workup, radiotherapy dosefractionation, treatment volume, and use of systemic therapy, several informative studies have been conducted in the last decade.

AREAS COVERED

This review examines the recent evidence to guide radiotherapy decision making in the SRT setting. Key topics include adjuvant vs salvage RT, utilization of molecular imaging and genomic classifiers, length of androgen deprivation therapy, inclusion of elective pelvic volume, and emerging role for hypofractionation.

EXPERT OPINION

Recently reported trials, conducted in an era prior to the routine use of molecular imaging and genomic classifiers, have been pivotal in establishing the current standard of care for SRT in prostate cancer. However, decisions about radiation treatment and systemic therapy may be tailored based on available prognostic and predictive biomarkers. Data from contemporary clinical trials are awaited to define and establish individualized, biomarker-driven approaches for SRT.

Dosimetric predictors of acute bowel toxicity after Stereotactic Body Radiotherapy (SBRT) in the definitive treatment of localized prostate cancer

INTRODUCTION

SBRT is an increasingly popular treatment for localized prostate cancer, though considerable variation in technical approach is common and optimal dose constraints are uncertain. In this study, we sought to identify dosimetric and patient-related predictors of acute rectal toxicity.

METHODS

Patients included in this study were treated with prostate SBRT on a prospective institutional protocol. Physician-graded toxicity and patient-reported outcomes were captured at one week, one month, and three months following SBRT. DVH data were extracted and converted into relative volume differential DVHs for NTCP modeling. Patient- and disease-related covariates along with NTCP model predictions were independently tested for significant association with physician-graded toxicity or a decline in bowel-related QoL. A multivariate model was constructed using forward selection, and significant parameter cutoff values were obtained with Fischer's exact test to group patients by risk of developing physician-graded toxicity or detriments in patient-reported QoL.

RESULTS

One hundred and three patients treated for localized prostate cancer with SBRT were included in our analysis. 52% of patients experienced a clinically significant decline in bowel-related QOL within 1 week of completion of treatment, while only 27.5% of patients developed grade 2+ physician-graded rectal toxicity. Sequential feature selection multivariate logistic regression identified rectal V22.5 Gy (p = 0.001) and D19% (p = 0.001) as independent predictors of clinically significant toxicity, while rectal V20Gy (p = 0.004) and D25.3% (p = 0.007) were independently correlated with physician-graded toxicity. Global multivariate step-wise logistic regression identified only D19% (p = 0.001) and V20Gy (p = 0.004) as independent predictors of acute bowel bother or physician-graded rectal toxicity respectively.

CONCLUSIONS

Moderate doses to large rectal volumes, D19% and V20Gy, were associated with an increased incidence of a clinically significant decrease in patient-reported bowel QOL and physician-scored grade 2+ rectal toxicity, respectively. These dosimetric parameters may help practitioners mitigate acute toxicity in patients treated with prostate SBRT.

Prostate-specific Membrane Antigen-radioguided Surgery Facilitates Pelvic Lymph Node Dissection During Radical Prostatectomy for the Treatment of Locally Advanced Prostate Cancer with Regional Lymph Node Metastases

Lymph node metastases (LNMs) are common in intermediate- to high-risk prostate cancer (PC) and may be missed during extended pelvic lymph node dissection (ePLND). Here we report on the use of prostate-specific membrane antigen (PSMA)-radioguided surgery (RGS) during open radical prostatectomy (RP) with ePLND to resect locoregional LNMs identified on preoperative PSMA positron emission tomography (PET). Preoperative PSMA PET showed 78 LNMs in 35 patients undergoing RP with ePLND and RGS between January 2018 and June 2020. In 14 patients (40%), LNMs were located outside the ePLND template. RGS achieved resection of PSMA-positive LNMs in 33/35 patients (94%). On univariable analysis, lower metastatic burden with up to two PSMA-positive LNMs on preoperative PET was associated with better postoperative outcomes. Limitations include the retrospective analysis and the small sample size. RGS facilitates resection of PSMA-positive LNs in patients treated with RP. Our data indicate a favorable treatment outcome in patients with low metastatic LN burden on preoperative PSMA PET. PATIENT SUMMARY: We investigated the use of radioactive guidance to remove lymph nodes affected by prostate cancer during surgical removal of the prostate. This approach can help to identify cancerous lymph nodes that might otherwise be missed and could lead to better survival outcomes.

Variability of radiotherapy volume delineation: PSMA PET/MRI and MRI based clinical target volume and lymph node target volume for high-risk prostate cancer

PURPOSE

A comparative retrospective study to assess the impact of PSMA Ligand PET/MRI ([68 Ga]-Ga-PSMA-11 and [18F]-F-PSMA-1007 PET/MRI) as a new method of target delineation compared to conventional imaging on whole-pelvis radiotherapy for high-risk prostate cancer (PCa).

PATIENTS AND METHODS

Forty-nine patients with primary high-risk PCa completed the whole-pelvis radiotherapy plan based on PSMA PET/MRI and MRI. The primary endpoint compared the size and overlap of clinical target volume (CTV) and nodal gross tumour volume (GTVn) based on PSMA PET/MRI and MRI. The diagnostic performance of two methods for pelvic lymph node metastasis (PLNM) was evaluated.

RESULTS

In the radiotherapy planning for high-risk PCa patients, there was a significant correlation between MRI-CTV and PET/MRI-CTV (P = 0.005), as well as between MRI-GTVn and PET/MRI-GTVn (P < 0.001). There are non-significant differences in the CTV and GTVn based on MRI and PET/MRI images (P = 0.660, P = 0.650, respectively). The conformity index (CI), lesion coverage factor (LCF) and Dice similarity coefficient (DSC) of CTVs were 0.999, 0.953 and 0.954. The CI, LCF and DSC of GTVns were 0.927, 0.284, and 0.32. Based on pathological lymph node analysis of 463 lymph nodes from 37 patients, the sensitivity, specificity of PET/MRI in the diagnosis of PLNM were 77.78% and 99.76%, respectively, which were higher than those of MRI (P = 0.011). Eight high-risk PCa patients who finished PSMA PET/MRI changed their N or M stage.

CONCLUSION

The CTV delineated based on PET/MRI and MRI differ little. The GTVn delineated based on PET/MRI encompasses metastatic pelvic lymph nodes more accurately than MRI and avoids covering pelvic lymph nodes without metastasis. We emphasize the utility of PET/MRI fusion images in GTVn delineation in whole pelvic radiotherapy for PCa. The use of PSMA PET/MRI aids in the realization of more individual and precise radiotherapy for PCa.