Prostate cancer radiation dose response: results of the M. D. Anderson phase III randomized trial

A Randomized Comparison of High Dose Rate and Low Dose Rate Prostate Brachytherapy Combined with External Beam Radiotherapy for Unfavourable Prostate Cancer: Efficacy Results after Median Follow-up 74 Months

PURPOSE

This single center randomized trial compared health-related QOL for men with unfavorable localized prostate cancer treated with combined pelvic external beam radiation (EBRT) and prostate brachytherapy (BT), randomly assigned to High Dose Rate (HDR) or Low Dose Rate (LDR). We now report efficacy outcomes with minimum 5 year follow up.

MATERIALS AND METHODS

Consenting patients receiving pelvic EBRT combined with prostate BT were randomized to either LDR (110Gy) or HDR (15Gy). Androgen deprivation was used in 76%. EBRT delivered 46 Gy/23 using IMRT or VMAT (68%) or 3DcRT (32%). Followup up was 1-, 3-, and 6-mo, then every 6 mo to 3 years, then annually. PSA ≤ 0.2ng/ml at 4 years defined cure. Biochemical failure-free survival (bFFS), and overall survival (OS) were calculated by Kaplan Meier methods. All failures were investigated by imaging (CT, bone scan and/or PSMA PET) ± biopsy if PET not available.

RESULTS

From 01/2014 to 12/2019, 195 men (42% IR/ 58% HR) were randomly assigned: 108 to HDR and 87 to LDR. Median age was 71 years. Median PSA was 11.6 ng/ml (mean 27.0 ng/ml). Median follow up was 74 months (43m - 116m). Median PSA nadirs were 0.07 and 0.08 in HDR and LDR (p=0.16), and time to nadir was 13.8 and 14.1 mo respectively (p=0.87). 4-year PSA ≤ 0.2 was maintained in 81% and 83% of HDR and LDR (p=0.91). 8-year bFFS (nadir+2) was 86% and 85% respectively. 18 of 22 BF have been identified: 3 are isolated LF while 14 are distant (isolated 11; 3 combined).

CONCLUSIONS

In this small, randomized comparison, efficacy analysis shows no difference between LDR and HDR boost in biochemical FFS at 5 and 8 years and confirms the excellent efficacy of dose escalation using prostate brachytherapy as documented in Ascende-RT for unfavorable localized prostate cancer.

Omission of Contralateral Systematic Biopsies in Unilateral Suspicious Prostate Cancer on Magnetic Resonance Imaging: Implications for Radiation Treatment Selection

Background and objective

A combined approach of magnetic resonance imaging (MRI) targeted biopsies (TBx) and systematic biopsies (SBx) was recommended previously in patients with unilateral suspicious prostate cancer (PCa) on MRI. Yet, new PCa guidelines suggest that contralateral SBx can be omitted. It is unknown how this guideline modification impacts treatment selection. This study evaluates the value of contralateral SBx in radiation treatment selection in patients with unilateral suspicious lesions (Prostate Imaging Reporting and Data System [PI-RADS] ≥3) on MRI.

Methods

Case files of 80 patients with a unilateral suspicious lesion on diagnostic MRI who underwent TBx and bilateral SBx were collected. The cases were presented to four radiation oncologists twice: once with diagnostic information of bilateral SBx and TBx, and once with diagnostic information of ipsilateral SBx and TBx pathology results. Based on this information, external beam radiation treatment (EBRT) fractionation scheme, duration of androgen deprivation therapy (ADT), and feasibility of brachytherapy (monotherapy or brachyboost) were considered.

Key findings and limitations

After omitting information of contralateral SBx pathology results, selection of EBRT fractionation scheme and ADT duration changed in 14% (95% confidence interval [CI] 9.8-17) and 15% (95% CI 11-19) of cases, respectively. The feasibility of brachytherapy as monotherapy and brachyboost, respectively, changed in 11% (95% CI 7.9-15) and in 21% (95% CI 17-26) of cases, with overall poor interobserver variability for both diagnostic scenarios (Fleiss' kappa 0.15 and 0.16).

Conclusions and clinical implications

Our findings indicate that omitting contralateral SBx has an impact on the treatment selection of patients who choose for radiation therapy as their treatment for locally confined PCa.

Patient summary

In patients with prostate cancer identified via magnetic resonance imaging on one side of the prostate, exclusion of prostate biopsies from the opposite side affected the selection of radiation treatment.

Biochemical outcome of prostate cancer patients treated with hypofractionated external radiation and a single high-dose-rate brachytherapy boost

INTRODUCTION

Treating localized high-risk prostate cancer with a combination of external beam radiation therapy (EBRT) and high-dose-rate brachytherapy (HDR-BT) is a common approach. Moderately hypofractionated EBRT and a single HDR-BT boost simplifies the treatment. We aim to present our five-year results.

METHODS

In this study, 355 patients treated with moderately hypofractionated EBRT (42 Gy in 14 fractions) and a single HDR-BT boost (14.5 Gy) at Örebro University Hospital between 2008 and 2018 were included. They were followed with regular PSA tests.

RESULTS

The median age of the cohort was 70 years (range: 51-81) and the median follow-up duration was 56 months (range: 6-150). Among them, 45% were classified as very high-risk, 38% as high-risk and 17% as intermediate-risk. Adjuvant androgen deprivation therapy (ADT) with a median duration of 24 months was given to 75% of the patient cohort. The estimated 5-year failure free survival rates were 79% (whole cohort), 66% (very high-risk), 90% (high-risk) and 85% (intermediate-risk), respectively. Initial PSA > 10 ng/mL, Gleason score 9-10 and tumor stage T3 were significantly associated with biochemical failure (BF). A PSA bounce occurred in 53 (15%) cases and was inversely associated with BF (p = 0.001) for patients receiving ADT.

CONCLUSIONS

Moderately hypofractionated EBRT and a single HDR-BT boost seems to be an effective treatment against intermediate- and high-risk localized prostate cancer. Treatment escalation strategies should be investigated for very high-risk patients where the risk of recurrence remains high.

[Short- and medium-term tolerance of hypofractionated prostate radiotherapy with simultaneous integrated boost]

PURPOSE

This retrospective study was conducted to ensure that irradiation of the pelvic lymph node areas associated with simultaneous hypofractionated boost to the prostate according to the protocol implemented at the university hospital of Tours (France) does not result in excess urinary and digestive toxicity in the short and medium term.

MATERIALS AND METHODS

The study population included patients with localized unfavourable intermediate or high-risk prostate cancer. The dose delivered was 65Gy in 25 fractions of 2.6Gy to the prostate and seminal vesicles, and 50Gy in 25 fractions of 2Gy to the pelvic lymph nodes. Acute toxicity events (between the start of radiotherapy and the first follow-up consultation) and medium-term toxicity events (after the first follow-up consultation) were assessed using the CTCAE version 5.0 classification.

RESULTS

Sixty-three patients were treated according to the protocol between January 1st, 2020, and October 31st, 2022. The majority of them had high-risk prostate cancer (79%). The median follow-up was 15 months. Very few patients reported grade 3-4 toxicity acutely (6% urinary and 0% digestive toxicity) or in the medium term (7% urinary and 0% and digestive toxicity).

CONCLUSION

Radiotherapy of pelvic lymph node areas with simultaneous hypofractionated boost to the prostate is feasible, with low rates of severe acute and medium-term toxicity.

Long-term evaluation of the safety of a rectal-prostate spacer, the ProSpace® balloon, in patients treated with radiotherapy for prostate cancer

BACKGROUND

Due to the close proximity of the prostate and rectum, rectal toxicity remains a major problem in patient treated by radiotherapy for prostate adenocarcinoma. One method of increasing the distance between the prostate and the rectum is to use a spacer implanted into the rectoprostatic space. This report describes the long-term outcomes obtained with a new ballon spacer.

METHODS

Patients treated with curative radiotherapy for low- or intermediate-risk prostate adenocarcinoma, who underwent insertion of the ProSpace® (BioProtect Ltd, Tzur Yigal, Israel) rectal-prostate balloon spacer, were included. The main objective was to evaluate the dosimetric benefit of the spacer for OARs. The secondary objectives were to evaluate the feasibility and tolerability of ProSpace® balloon placement and to evaluate its long-term therapeutic efficacy and tolerance.

RESULTS

Between October 2013 and March 2015, 16 patients were enrolled in the Pasteur Clinic, Toulouse, France. The median follow-up was 85.5 months. From top to bottom, the space created was a mean of 16.3 mm (range: 11-20.5 mm) at the base of the prostate, 12.1 mm (range: 4-16 mm) at the middle and 8.9 mm at the apex (range: 5-15 mm). On average, rectal volumes receiving a dose of 70 Gy, 60 Gy and 50 Gy were significantly lower after balloon implantation: -4.81 cc (1.5 vs. 6.3; p < 0.0005), -8.08 cc (6.4 vs. 14.5; p = 0.002) and -9.06 cc (16.7 vs. 25.7; p = 0.003), respectively. There were significant differences in coverage after balloon implantation: Median V95% (p < 0.0005), median Dmin (p = 0.01) and median V98% (p < 0.001) were higher after balloon implantation. At 5 years, cumulative gastrointestinal toxicity was grade 1 in 6% (1/16 patients). No toxicity of grade 2 or higher was found. At 5 years, no urinary toxicity grade 3 or 4 toxicity was found. The QoL was not deteriorated.

CONCLUSIONS

The use of the ProSpace® balloon seems to be well accepted by patients, allowing a double dosimetric gain: a decrease in doses received by the rectum and an improvement in the coverage of the high-risk PTV. The long-term gastrointestinal toxicity remains low and QoL is preserved in all treated patients.

The influence of Gleason score ≤ 6 histology on the outcome of high-risk localized prostate cancer after modern radiotherapy

We aimed to retrospectively review outcomes in patients with high-risk prostate cancer and a Gleason score ≤ 6 following modern radiotherapy. We analyzed the outcomes of 1374 patients who had undergone modern radiotherapy, comprising a high-risk low grade [HRLG] group (Gleason score ≤ 6; n = 94) and a high-risk high grade [HRHG] group (Gleason score ≥ 7, n = 1125). We included 955 patients who received brachytherapy with or without external beam radio-therapy (EBRT) and 264 who received modern EBRT (intensity-modulated radiotherapy [IMRT] or stereotactic body radiotherapy [SBRT]). At a median follow-up of 60 (2-177) months, actuarial 5-year biochemical failure-free survival rates were 97.8 and 91.8% (p = 0.017), respectively. The frequency of clinical failure in the HRLG group was less than that in the HRHG group (0% vs 5.4%, p = 0.012). The HRLG group had a better 5-year distant metastasis-free survival than the HRHG group (100% vs 96.0%, p = 0.035). As the HRLG group exhibited no clinical failure and better outcomes than the HRHG group, the HRLG group might potentially be classified as a lower-risk group.

Multiparametric Magnetic Resonance Imaging- Guided Dose-Escalated Radiation Therapy for Localized Prostate Cancer: A Prospective Phase 2 Trial

PURPOSE

This trial's purpose was to determine the late toxicity associated with dose escalation to Prostate Imaging Reporting and Data System (PI-RADS) III-V lesions on multiparametric magnetic resonance imaging (MRI) with an image guided combined IMRT-stereotactic body radiation therapy (SBRT) approach in men with localized prostate cancer.

METHODS AND MATERIALS

In this phase 2 trial patients with localized prostate cancer with clinical tumor stage T1-T3bN0 and at least one PIRADS III-V lesion were recruited to receive 45 Gy in 25 fractions to the prostate and seminal vesicles followed by a boost of 18 Gy in 3 fractions to the prostate with a simultaneous integrated boost 21 Gy in 3 fractions to the PI-RADS lesion(s). The primary endpoint was the cumulative incidence of late grade ≥3 genitourinary and gastrointestinal toxicity by 18 months (National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0).

RESULTS

Overall, 50 patients were enrolled in this study, and 43 patients completed at least 18 months of follow-up. The cumulative incidence of grade 1, 2, and 3 late genitourinary toxicity at 18 months was 18%, 53%, and 2%. One patient was noted to have grade 3 hematuria and needed cystoscopy-guided cauterization. No acute grade 3 gastrointestinal or genitourinary toxicities were observed. The cumulative incidence of grade 1, 2, and 3 late gastrointestinal toxicity at 18 months was 31%, 4%, and 0%, respectively. At a median follow-up of 43.5 months, 3 patients developed biochemical recurrence, each with distant bone metastases without local or nodal recurrence. At 3 years, freedom from biochemical failure rate was 95.3% (95% CI, 89.2%-100%).

CONCLUSIONS

Multiparametric MRI-guided dose escalation to PI-RADS III-V lesions using a combined image guided IMRT-SBRT approach is associated with an acceptable risk of late gastrointestinal and genitourinary toxicity. The results should be interpreted with caution considering their single institutional nature, small sample size, and short follow-up and should be validated in a larger study.

A Randomized Feasibility Trial of Stereotactic Prostate Radiation Therapy With or Without Elective Nodal Irradiation in High-Risk Localized Prostate Cancer (SPORT Trial)

PURPOSE

The aim of this study was to establish the feasibility of a randomized clinical trial comparing SABR with prostate-only (P-SABR) or with prostate plus pelvic lymph nodes (PPN-SABR) in patients with unfavorable intermediate- or high-risk localized prostate cancer and to explore potential toxicity biomarkers.

METHODS AND MATERIALS

Thirty adult men with at least 1 of the following features were randomized 1:1 to P-SABR or PPN-SABR: clinical magnetic resonance imaging stage T3a N0 M0, Gleason score ≥7 (4+3), and prostate-specific antigen >20 ng/mL. P-SABR patients received 36.25 Gy/5 fractions/29 days, and PPN-SABR patients received 25 Gy/5 fractions to pelvic nodes, with the final cohort receiving a boost to the dominant intraprostatic lesion of 45 to 50 Gy. Phosphorylated gamma-H2AX (γH2AX) foci numbers, citrulline levels, and circulating lymphocyte counts were quantified. Acute toxicity information (Common Terminology Criteria for Adverse Events, version 4.03) was collected weekly at each treatment and at 6 weeks and 3 months. Physician-reported late Radiation Therapy Oncology Group (RTOG) toxicity was recorded from 90 days to 36 months postcompletion of SABR. Patient-reported quality of life (Expanded Prostate Cancer Index Composite and International Prostate Symptom Score) scores were recorded with each toxicity time point.

RESULTS

The target recruitment was achieved, and treatment was successfully delivered in all patients. A total of 0% and 6.7% (P-SABR) and 6.7% and 20.0% (PPN-SABR) experienced acute grade ≥2 gastrointestinal (GI) and genitourinary (GU) toxicity, respectively. At 3 years, 6.7% and 6.7% (P-SABR) and 13.3% and 33.3% (PPN-SABR) had experienced late grade ≥2 GI and GU toxicity, respectively. One patient (PPN-SABR) had late grade 3 GU toxicity (cystitis and hematuria). No other grade ≥3 toxicity was observed. In addition, 33.3% and 60% (P-SABR) and 64.3% and 92.9% (PPN-SABR) experienced a minimally clinically important change in late Expanded Prostate Cancer Index Composite bowel and urinary summary scores, respectively. γH2AX foci numbers at 1 hour after the first fraction were significantly higher in the PPN-SABR arm compared with the P-SABR arm (P = .04). Patients with late grade ≥1 GI toxicity had significantly greater falls in circulating lymphocytes (12 weeks post-radiation therapy, P = .01) and a trend toward higher γH2AX foci numbers (P = .09) than patients with no late toxicity. Patients with late grade ≥1 bowel toxicity and late diarrhea experienced greater falls in citrulline levels (P = .05).

CONCLUSIONS

A randomized trial comparing P-SABR with PPN-SABR is feasible with acceptable toxicity. Correlations of γH2AX foci, lymphocyte counts, and citrulline levels with irradiated volume and toxicity suggest potential as predictive biomarkers. This study has informed a multicenter, randomized, phase 3 clinical trial in the United Kingdom.

Radiological evaluation of an iodised hydrogel for prostate radiotherapy applications

PURPOSE

Physical separation of healthy tissue and target volumes in prostate radiotherapy through the insertion of hydrogel can improve patient toxicity rates. An iodised hydrogel may provide anatomical separation of prostate and rectum while being easily visualised through radio-opacity. The aim of this study was to characterise SpaceOAR Vue™ in kilovoltage (kV) images and megavoltage (MV) radiotherapy treatment planning.

METHODS

Two cassettes were 3D-printed, one filled with water and the other with SpaceOAR Vue™. Transmission dose through each cassette was measured in slab phantom geometry and compared for 6MV and 10MV photon energies. The SpaceOAR Vue™ slab phantom setup was simulated using computed tomography (CT) and a treatment plan created. The plan was calculated with the hydrogel segmented and material assignment set to water, and the resultant dose compared to corresponding measurement doses. The first 5 patients treated with SpaceOAR Vue™ were assessed with the volume and Hounsfield units (HU) of the hydrogel evaluated in CT and cone beam computed tomography (CBCT) imaging.

RESULTS

Transmission through Water and SpaceOAR Vue™ agreed to within 0.5% for both photon energies. Furthermore, the segmentation of SpaceOAR Vue™ and material assignment to water, resulted in a plan dose that agreed to measurement to within 0.5%. Clinically, the SpaceOAR Vue™ volume and HU did not vary over patient treatment course, however was found to display differently on different kV imaging modalities.

CONCLUSIONS

SpaceOAR Vue™ was found to be radio-opaque on kV images, but dosimetrically behaved similarly to water in MV treatment beams, making it suitable for clinical use.

Rapid unpaired CBCT-based synthetic CT for CBCT-guided adaptive radiotherapy

In this work, we demonstrate a method for rapid synthesis of high-quality CT images from unpaired, low-quality CBCT images, permitting CBCT-based adaptive radiotherapy. We adapt contrastive unpaired translation (CUT) to be used with medical images and evaluate the results on an institutional pelvic CT dataset. We compare the method against cycleGAN using mean absolute error, structural similarity index, root mean squared error, and Frèchet Inception Distance and show that CUT significantly outperforms cycleGAN while requiring less time and fewer resources. The investigated method improves the feasibility of online adaptive radiotherapy over the present state-of-the-art.

Identification of Key Elements in Prostate Cancer for Ontology Building via a Multidisciplinary Consensus Agreement

BACKGROUND

Clinical data collection related to prostate cancer (PCa) care is often unstructured or heterogeneous among providers, resulting in a high risk for ambiguity in its meaning when sharing or analyzing data. Ontologies, which are shareable formal (i.e., computable) representations of knowledge, can address these challenges by enabling machine-readable semantic interoperability. The purpose of this study was to identify PCa-specific key data elements (KDEs) for standardization in clinic and research.

METHODS

A modified Delphi method using iterative online surveys was performed to report a consensus agreement on KDEs by a multidisciplinary panel of 39 PCa specialists. Data elements were divided into three themes in PCa and included (1) treatment-related toxicities (TRT), (2) patient-reported outcome measures (PROM), and (3) disease control metrics (DCM).

RESULTS

The panel reached consensus on a thirty-item, two-tiered list of KDEs focusing mainly on urinary and rectal symptoms. The Expanded Prostate Cancer Index Composite (EPIC-26) questionnaire was considered most robust for PROM multi-domain monitoring, and granular KDEs were defined for DCM.

CONCLUSIONS

This expert consensus on PCa-specific KDEs has served as a foundation for a professional society-endorsed, publicly available operational ontology developed by the American Association of Physicists in Medicine (AAPM) Big Data Sub Committee (BDSC).

Comparison of four-year toxicities and local control of ultra-hypofractionated vs moderate-hypofractionated image guided prostate radiation with HDR brachytherapy boost: A phase I-II single institution trial

Purpose/Objectives

To analyze the long term efficacy and safety of an ultra-hypofractionated (UHF) radiation therapy prostate treatment regimen with HDR brachytherapy boost (BB) and compare it to moderate-hypofractionated regimens (MHF).

Materials/Methods

In this single arm, prospective monocentric study, 28 patients with intermediate risk prostate cancer were recruited in an experimental treatment arm of 25 Gy in 5 fractions plus a 15 Gy HDR BB. They were then compared to two historical control groups, treated with either 36 Gy in 12 fractions or 37.5 Gy in 15 fractions with a similar HDR BB. The control groups included 151 and 311 patients respectively. Patient outcomes were reported using the International Prostate Symptom Score (IPSS) and Expanded Prostate Index Composite (EPIC-26) questionnaires at baseline and at each follow-up visit.

Results

Median follow-up for the experimental arm was 48.5 months compared to 47 months and 60 months compared to the 36/12 and 37,5/15 groups respectively. The IPSS and EPIC scores did not demonstrate any significant differences in the gastrointestinal or genitourinary domains between the three groups over time. No biochemical recurrence occurred in the UHF arm as defined by the Phoenix criterion.

Conclusion

The UHF treatment scheme with HDR BB seems equivalent to standard treatment arms in terms of toxicities and local control. Randomized control trials with larger cohorts are ongoing and needed to further confirm our findings.

Toxicity of dose-escalated radiotherapy up to 84 Gy for prostate cancer

PURPOSE

The outcome of radiotherapy (RT) for prostate cancer (PCA) depends on the delivered dose. While the evidence for dose-escalated RT up to 80 gray (Gy) is well established, there have been only few studies examining dose escalation above 80 Gy. We initiated the present study to assess the safety of dose escalation up to 84 Gy.

METHODS

In our retrospective analysis, we included patients who received dose-escalated RT for PCA at our institution between 2016 and 2021. We evaluated acute genitourinary (GU) and gastrointestinal (GI) toxicity as well as late GU and GI toxicity.

RESULTS

A total of 86 patients could be evaluated, of whom 24 patients had received 80 Gy and 62 patients 84 Gy (35 without pelvic and 27 with pelvic radiotherapy). Regarding acute toxicities, no > grade 2 adverse events occurred. Acute GU/GI toxicity of grade 2 occurred in 12.5%/12.5% of patients treated with 80 Gy, in 25.7%/14.3% of patients treated with 84 Gy to the prostate only, and in 51.9%/12.9% of patients treated with 84 Gy and the pelvis included. Late GU/GI toxicity of grade ≥ 2 occurred in 4.2%/8.3% of patients treated with 80 Gy, in 7.1%/3.6% of patients treated with 84 Gy prostate only, and in 18.2%/0% of patients treated with 84 Gy pelvis included (log-rank test p = 0.358).

CONCLUSION

We demonstrated that dose-escalated RT for PCA up to 84 Gy is feasible and safe without a significant increase in acute toxicity. Further follow-up is needed to assess late toxicity and survival.

Dose-escalated radiotherapy for clinically localized and locally advanced prostate cancer

BACKGROUND

Treatments for clinically localized prostate cancer include radical prostatectomy, external beam radiation therapy, brachytherapy, active surveillance, hormonal therapy, and watchful waiting. For external beam radiation therapy, oncological outcomes may be expected to improve as the dose of radiotherapy (RT) increases. However, radiation-mediated side effects on surrounding critical organs may also increase.

OBJECTIVES

To assess the effects of dose-escalated RT in comparison with conventional dose RT for curative treatment of clinically localized and locally advanced prostate cancer.

SEARCH METHODS

We performed a comprehensive search using multiple databases including trial registries and other sources of grey literature, up until 20 July 2022. We applied no restrictions on publication language or status.

SELECTION CRITERIA

We included parallel-arm randomized controlled trials (RCTs) of definitive RT in men with clinically localized and locally advanced prostate adenocarcinoma. RT was dose-escalated RT (equivalent dose in 2 Gy [EQD2] ≥ 74 Gy, lesser than 2.5 Gy per fraction) versus conventional RT (EQD2 < 74 Gy, 1.8 Gy or 2.0 Gy per fraction). Two review authors independently classified studies for inclusion or exclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted data from the included studies. We performed statistical analyses by using a random-effects model and interpreted them according to the Cochrane Handbook for Systematic Reviews of Interventions. We used GRADE guidance to rate the certainty of the evidence of RCTs.

MAIN RESULTS

We included nine studies with 5437 men in an analysis comparing dose-escalated RT versus conventional dose RT for the treatment of prostate cancer. The mean participant age ranged from 67 to 71 years. Almost all men had localized prostate cancer (cT1-3N0M0). Primary outcomes Dose-escalated RT probably results in little to no difference in time to death from prostate cancer (hazard ratio [HR] 0.83, 95% CI 0.66 to 1.04; I2 = 0%; 8 studies; 5231 participants; moderate-certainty evidence). Assuming a risk of death from prostate cancer of 4 per 1000 at 10 years in the conventional dose RT group, this corresponds to 1 fewer men per 1000 (1 fewer to 0 more) dying of prostate cancer in the dose-escalated RT group. Dose-escalated RT probably results in little to no difference in severe RT toxicity of grade 3 or higher late gastrointestinal (GI) toxicity (RR 1.72, 95% CI 1.32 to 2.25; I2 = 0%; 8 studies; 4992 participants; moderate-certainty evidence); 23 more men per 1000 (10 more to 40 more) in the dose-escalated RT group assuming severe late GI toxicity as 32 per 1000 in the conventional dose RT group. Dose-escalated RT probably results in little to no difference in severe late genitourinary (GU) toxicity (RR 1.25, 95% CI 0.95 to 1.63; I2 = 0%; 8 studies; 4962 participants; moderate-certainty evidence); 9 more men per 1000 (2 fewer to 23 more) in the dose-escalated RT group assuming severe late GU toxicity as 37 per 1000 in the conventional dose RT group. Secondary outcomes Dose-escalated RT probably results in little to no difference in time to death from any cause (HR 0.98, 95% CI 0.89 to 1.09; I2 = 0%; 9 studies; 5437 participants; moderate-certainty evidence). Assuming a risk of death from any cause of 101 per 1000 at 10 years in the conventional dose RT group, this corresponds to 2 fewer men per 1000 (11 fewer to 9 more) in the dose-escalated RT group dying of any cause. Dose-escalated RT probably results in little to no difference in time to distant metastasis (HR 0.83, 95% CI 0.57 to 1.22; I2 = 45%; 7 studies; 3499 participants; moderate-certainty evidence). Assuming a risk of distant metastasis of 29 per 1000 in the conventional dose RT group at 10 years, this corresponds to 5 fewer men per 1000 (12 fewer to 6 more) in the dose-escalated RT group developing distant metastases. Dose-escalated RT may increase overall late GI toxicity (RR 1.27, 95% CI 1.04 to 1.55; I2 = 85%; 7 studies; 4328 participants; low-certainty evidence); 92 more men per 1000 (14 more to 188 more) in the dose-escalated RT group assuming overall late GI toxicity as 342 per 1000 in the conventional dose RT group. However, dose-escalated RT may result in little to no difference in overall late GU toxicity (RR 1.12, 95% CI 0.97 to 1.29; I2 = 51%; 7 studies; 4298 participants; low-certainty evidence); 34 more men per 1000 (9 fewer to 82 more) in the dose-escalated RT group assuming overall late GU toxicity as 283 per 1000 in the conventional dose RT group. Based on long-term follow-up (up to 36 months), dose-escalated RT may result or probably results in little to no difference in the quality of life using 36-Item Short Form Survey; physical health (MD -3.9, 95% CI -12.78 to 4.98; 1 study; 300 participants; moderate-certainty evidence) and mental health (MD -3.6, 95% CI -83.85 to 76.65; 1 study; 300 participants; low-certainty evidence), respectively.

AUTHORS' CONCLUSIONS

Compared to conventional dose RT, dose-escalated RT probably results in little to no difference in time to death from prostate cancer, time to death from any cause, time to distant metastasis, and RT toxicities (except overall late GI toxicity). While dose-escalated RT may increase overall late GI toxicity, it may result, or probably results, in little to no difference in physical and mental quality of life, respectively.

Standard and Hypofractionated Dose Escalation to Intraprostatic Tumor Nodules in Localized Prostate Cancer: 5-Year Efficacy and Toxicity in the DELINEATE Trial

PURPOSE

Our purpose was to report 5-year efficacy and toxicity of intraprostatic lesion boosting using standard and hypofractionated radiation therapy.

METHODS AND MATERIALS

DELINEATE (ISRCTN 04483921) is a single center phase 2 multicohort study including standardly fractionated (cohort A: 74 Gy/37F to prostate and seminal vesicles [PSV]; cohort C 74 Gy/37F to PSV plus 60 Gy/37F to pelvic lymph nodes) and moderately hypofractionated (cohort B: 60 Gy/20F to PSV) prostate intensity-modulated radiation therapy patients with National Comprehensive Cancer Network intermediate/high-risk disease. Patients received an integrated boost of 82 Gy (cohorts A and C) or 67 Gy (cohort B) to multiparametric magnetic resonance imaging identified lesion(s). Primary endpoint was late Radiation Therapy Oncology Group (RTOG) gastrointestinal (GI) toxicity at 1 year. Secondary endpoints were acute and late toxicity (clinician and patient reported) and freedom from biochemical/clinical failure at 5 years.

RESULTS

Two hundred and sixty-five men were recruited and 256 were treated (55 cohort A, 153 cohort B, and 48 cohort C). Median follow-up for each cohort was >5 years. Cumulative late RTOG grade 2+ GI toxicity at 1 year was 3.6% (95% confidence interval [CI], 0.9%-13.8%) (cohort A), 7.2% (95% CI, 4%-12.6%) (cohort B), and 8.4% (95% CI, 3.2%-20.8%) (cohort C). Cumulative late RTOG grade 2+ GI toxicity to 5 years was 12.8% (95% CI, 6.3%-25.1%) (cohort A), 14.6% (95% CI, 9.9%-21.4%) (cohort B), and 20.7% (95% CI, 11.2%-36.2%) (cohort C). Cumulative RTOG grade 2+ genitourinary toxicity to 5 years was 12.9% (95% CI, 6.4%-25.2%) (cohort A), 18.2% (95% CI, 12.8%-25.4%) (cohort B), and 18.2% (95% CI, 9.5%-33.2%) (cohort C). Five-year freedom from biochemical/clinical failure was 98.2% (95% CI, 87.8%-99.7%) (cohort A), 96.7% (95% CI, 91.3%- 98.8%) (cohort B), and 95.1% (95% CI, 81.6-98.7%) (cohort C).

CONCLUSIONS

The DELINEATE trial has shown safety, tolerability, and feasibility of focal boosting in 20 or 37 fractions. Efficacy results indicate a low chance of prostate cancer recurrence 5 years after radiation therapy. Evidence from ongoing phase 3 randomized trials is awaited.

A clinical study comparing polymer and gold fiducials for prostate cancer radiotherapy

Introduction

Image guidance with gold fiducials improves outcomes of prostate radiotherapy. However, gold produces artefact on CT imaging, interfering with contouring and verification. The purpose of this study was to compare polymer to standard gold fiducials using radiotherapy imaging modalities to assess the visibility and artefact.

Methods

Twenty eight patients with locally advanced prostate cancer were enrolled, half had three polymer fiducials implanted into the prostate and half underwent insertion of gold fiducials. Patients were imaged with CT, T2 weighted MRI, cone-beam CT (CBCT) and planar KV images. Fiducials were scored for visibility and assessed for CT artefact in surrounding prostate tissue. The artefact was quantified from Hounsfield number histograms and separated into percentile ranges and proportion of voxels in HU normal tissue range of a 2cm sphere surrounding the fiducial.

Results

Gold and polymer fiducials were sufficiently visible for CT and CBCT verification. The gold fiducials could be visualized well on KV planar imaging; however, the polymer markers were obscured by pelvic bones. Neither polymer nor gold fiducials could be visualized on MRI. The polymer fiducial produced less artefact than gold on CT, having less voxel spread for the HU percentile ranges and a greater proportion of voxels in the normal tissue range.

Conclusions

Polymer fiducials are a more suitable fiducial than gold for CT/CBCT in prostate cancer radiotherapy, demonstrating minimal artefact and good visibility on CT. However, they were not well seen on MRI or KV imaging and thus not suitable for co-registration or planar KV verification.

Pattern of Radiotherapy Treatment in Low-Risk, Intermediate-Risk, and High-Risk Prostate Cancer Patients: Analysis of National Cancer Database

Background: In this study, the utilization rates and survival outcomes of different radiotherapy techniques are compared in prostate cancer (PCa) patients stratified by risk group. Methods: We analyzed an extensive data set of N0, M0, non-surgical PCa patients diagnosed between 2004 and 2015 from the National Cancer Database (NCDB). Patients were grouped into six categories based on RT modality: an intensity-modulated radiation therapy (IMRT) group with brachytherapy (BT) boost, IMRT with/without IMRT boost, proton therapy, stereotactic body radiation therapy (SBRT), low-dose-rate brachytherapy (BT LDR), and high-dose-rate brachytherapy (BT HDR). Patients were also stratified by the National Comprehensive Cancer Network (NCCN) guidelines: low-risk (clinical stage T1−T2a, Gleason Score (GS) ≤ 6, and Prostate-Specific Antigen (PSA) < 10), intermediate-risk (clinical stage T2b or T2c, GS of 7, or PSA of 10−20), and high-risk (clinical stage T3−T4, or GS of 8−10, or PSA > 20). Overall survival (OS) probability was determined using a Kaplan−Meier estimator. Univariate and multivariate analyses were performed by risk group for the six treatment modalities. Results: The most utilized treatment modality for all PCa patients was IMRT (53.1%). Over the years, a steady increase in SBRT utilization was observed, whereas BT HDR usage declined. IMRT-treated patient groups exhibited relatively lower survival probability in all risk categories. A slightly better survival probability was observed for the proton therapy group. Hormonal therapy was used for a large number of patients in all risk groups. Conclusion: This study revealed that IMRT was the most common treatment modality for PCa patients. Brachytherapy, SBRT, and IMRT+BT exhibited similar survival rates, whereas proton showed slightly better overall survival across the three risk groups. However, analysis of the demographics indicates that these differences are at least in part due to selection bias.

Functional imaging-guided carbon ion irradiation with simultaneous integrated boost for localized prostate cancer: study protocol for a phase II randomized controlled clinical trial

Background

Due to the physical dose distribution characteristic of “Bragg peak” and the biological effect as a kind of high linear energy transfer ray, heavy ion therapy has advantages over conventional photon therapy in both efficacy and safety. Based on the evidence that prostate cancer lesions before treatment are the most common sites of tumor residual or recurrence after treatment, simultaneous integrated boost radiation therapy for prostate cancer has been proven to have the advantage of improving efficacy without increasing toxicities.

Methods

This study is a prospective phase II randomized controlled clinical trial evaluating the efficacy and safety of functional imaging-guided carbon ion irradiation with simultaneous integrated boost for localized prostate cancer. One hundred and forty patients with localized prostate cancer will be randomized into carbon ion radiotherapy group and simultaneous integrated boost carbon ion radiotherapy group at a 1:1 ratio. The primary endpoint is to compare the incidence of treatment-related grade 2 and higher acute toxicities between the two groups according to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 4.03. Secondary endpoints are late toxicities, biochemical relapse-free survival, overall survival, progression-free survival, and quality of life.

Discussion

This study adopts functional imaging-guided simultaneous integrated boost of carbon ion radiotherapy for localized prostate cancer, aiming to evaluate the differences in the severity and incidence of acute toxicities in patients with localized prostate cancer treated with carbon ion radiotherapy and simultaneous integrated boost carbon ion radiotherapy, in order to optimize the carbon ion treatment strategy for localized prostate cancer.

Trial registration

ClinicalTrials.gov NCT05010343. Retrospectively registered on 18 August 2021

Dose-escalation in prostate cancer: Results of randomized trials

In 1998, an editorial from the International Journal of Radiation Oncology - Biology - Physics (IJROBP) on the occasion of the publication of Phase I by Zelefsky et al. on 3D radiotherapy dose escalation asked the question: "will more prove better?". More than 20 years later, several prospective studies have supported the authors' conclusions, making dose escalation a new standard in prostate cancer. The data from prospective randomized studies were ultimately disappointing in that they failed to show an overall survival benefit from dose escalation. However, there is a clear and consistent benefit in biochemical recurrence-free survival, which must be weighed on an individual patient basis against the potential additional toxicity of dose escalation. Techniques and concepts have become more and more precise, such as intensity modulated irradiation, simultaneous integrated boost, hypofractionated dose-escalation, pelvic irradiation with involved node boost or focal dose-escalation on gross recurrence after prostatectomy. The objective here was to summarize the prospective data on dose escalation in prostate cancer and in particular on recent advances in the field. In 2022, can we finally say that more has proven better?

Long-term outcomes of prostate intensity-modulated radiation therapy incorporating a simultaneous intra-prostatic MRI-directed boost

Purpose/objectives

This retrospective study demonstrates the long-term outcomes of treating prostate cancer using intensity modulated (IMRT) with incorporation of MRI-directed boost.

Materials/methods

From February 2009 to February 2013, 78 men received image-guided IMRT delivering 77.4 Gy in 44 fractions with simultaneously integrated boost to 81-83 Gy to an MRI-identified lesion. Patients with intermediate-risk or high-risk prostate cancer were recommended to receive 6 and 24-36 months of adjuvant hormonal therapy, respectively.

Results

Median follow-up was 113 months (11-147). There were 18 low-risk, 43 intermediate-risk, and 17 high-risk patients per NCCN risk stratification included in this study. Adjuvant hormonal therapy was utilized in 32 patients (41%). The 10-year biochemical control rate for all patients was 77%. The 10-year biochemical control rates for low-risk, intermediate-risk, and high-risk diseases were 94%, 81%, and 88%, respectively (p = 0.35). The 10-year rates of local control, distant control, and survival were 99%, 88%, and 66%, respectively. Of 25 patients who died, only four (5%) died of prostate cancer. On univariate analysis, T-category and pretreatment PSA level were associated with distant failure rate (p = 0.02). There was no grade =3 genitourinary and gastrointestinal toxicities that persisted at the last follow-up.

Conclusions

This study demonstrated the long-term efficacy of using MRI to define an intra-prostatic lesion for SIB to 81-83Gy while treating the entire prostate gland to 77.4 Gy with IMRT. Our study confirms that modern MRI can be used to locally intensify dose to prostate tumors providing high long-term disease control while maintaining favorable long-term toxicity.

Results of a prospective randomized trial on long-term effectiveness of protons and carbon ions in prostate cancer: LEM I and α/β = 2 Gy overestimates the RBE

AIM

To analyze the long-term effectiveness of carbon ions relative to protons in the prospective randomized controlled ion prostate irradiation (IPI) trial.

METHODS

Effectiveness via PSA assessment in a randomized study on prostate irradiation with 20x3.3 Gy(RBE) protons versus carbon ions was analyzed in 92 patients. Proton RBE was based on a fixed RBE of 1.1 while the local effect model (LEM) I and an α/β = 2 Gy was used for carbon ions. The dose in the prostate was recalculated based on the delivered treatment plan using LEM I and LEM IV and different α/β values.

RESULTS

Five-year overall and progression free survival was 98% and 85% with protons and 91% and 50% with carbon ions, respectively, with the latter being unexpectedly low compared to Japanese carbon ion data and rather corresponding to a photon dose <72 Gy in 2 Gy fractions. According to LEM I and the applied α/β-value of 2 Gy, the applied carbon ion dose in 2 Gy(RBE) fractions (EQD2) was 87.46 Gy(RBE). Recalculations confirmed a strong dependence of RBE-weighted dose on the α/β ratio as well as on the RBE-model.

CONCLUSION

The data demonstrate a significant lower effectiveness of the calculated RBE-weighted dose in the carbon ion as compared to the proton arm. LEM I and an α/β = 2 Gy overestimates the RBE for carbon ions in prostate cancer treatment. Adjusting the biological dose calculation by using LEM I with α/β = 4 Gy could be a pragmatic way to safely escalate dose in carbon ion radiotherapy for prostate cancer.

Modulation of Peripheral Immune Cell Subpopulations After RapidArc/Moderate Hypofractionated Radiotherapy for Localized Prostate Cancer: Findings and Comparison With 3D Conformal/Conventional Fractionation Treatment

Radiotherapy (RT) is an important therapeutic option in patients with localized prostate cancer (PC). Unfortunately, radiation treatment causes a decrease in peripheral lymphocytes and, consequently, influences the patients' immune status. Our aim was to study changes in peripheral blood immune cell subpopulations after RT and during 6 months' follow-up in 2 groups of PC patients irradiated with different techniques and dose fractions with curative intent. We also investigated the presence of correlation between immune cell modulation and genitourinary or gastrointestinal toxicity. We enrolled 44 patients treated with curative RT (RapidArc/hypofractionation regimen or 3D conformal/conventional fractionation) for localized PC. Total white blood cell (WBC), absolute lymphocyte counts (ALCs), and peripheral immune cell subpopulations were analyzed at baseline, at the end of RT, and 3 and 6 months after the end of RT. WBC and ALC greatly decreased at the end of RT with a trend to recover at 6 months' follow-up in the hypofractionation group but not in the conventional one. Furthermore, B, total T, T CD4+, T CD8+, and NK cell values dropped significantly in both groups at the end of RT, with a minor decrease detectable in the hypofractionation group for B, total T, and T CD4+ lymphocytes with respect to the other technique/fractionation group. Double-negative T (DNT), double-positive T (DPT), and NKT cells significantly decreased at the end of RT with a slight tendency to recover values during follow-up, particularly in the hypofractionation group. No correlation with genitourinary or gastrointestinal toxicity was found. In this study, we showed, for the first time, the effects of RapidArc/moderate hypofractionation RT on immune cell subsets in patients treated for localized PC. Due to the growing interest in minority T-cell subpopulations for immunotherapy, we also reported longitudinal monitoring of the effects of RT on DNT, DPT, and NKT, which was never studied before. Our preliminary data highlight the importance of considering the effects of different RT techniques/fractionation regimens on peripheral immune cells, in the era of RT and immunotherapy combination.

Race-specific prostate cancer outcomes in a cohort of low and favorable-intermediate risk patients who underwent external beam radiation therapy from 1990 to 2017

BACKGROUND

Previous research exploring the role of race on prostate cancer (PCa) outcomes has demonstrated greater rates of disease progression and poorer overall survival for African American (AA) compared to Caucasian American (CA) men. The current study examines self-reported race as a predictor of long-term PCa outcomes in patients with low and favorable-intermediate risk disease treated with external beam radiation therapy (EBRT).

METHODS

This retrospective cohort study examined patients who were consented to enrollment in the Center for Prostate Disease Research Multicenter National Database between January 01, 1990 and December 31, 2017. Men self-reporting as AA or CA who underwent EBRT for newly diagnosed National Comprehensive Cancer Network-defined low or favorable-intermediate risk PCa were included. Dependent study outcomes included: biochemical recurrence-free survival, (ii) distant metastasis-free survival, and (iii) overall survival. Each outcome was modeled as a time-to-event endpoint using race-stratified Kaplan-Meier estimation curves and multivariable Cox proportional hazards analysis.

RESULTS

Of 840 men included in this study, 268 (32%) were AA and 572 (68%) were CA. The frequency of biochemical recurrence, distant metastasis, and deaths from any cause was 151 (18.7%), 29 (3.5%), and 333 (39.6%), respectively. AA men had a significantly younger median age at time of EBRT and slightly higher biopsy Gleason scores. Multivariable Cox proportional hazards analyses demonstrated no racial differences in any of the study endpoints.

CONCLUSIONS

These findings reveal no racial disparity in PCa outcomes for AA compared to CA men, in a long-standing, longitudinal cohort of patients with comparable access to cancer care.

Brachytherapy focal dose escalation using ultrasound based tissue characterization by patients with non-metastatic prostate cancer: Five-year results from single-center phase 2 trial

PURPOSE

This prospective trial investigates side effects and efficacy of focal dose escalation with brachytherapy for patients with prostate cancer.

METHODS AND MATERIALS

In the Phase II, monocentric prospective trial 101 patients with low-/intermediate- and high-risk prostate cancer were enrolled between 2011 and 2013. Patients received either PDR-/HDR-brachytherapy alone with 86-90 Gy (EQD2, α/β = 3 Gy) or PDR-/HDR-brachytherapy as boost after external beam radiation therapy up to a total dose of 91-96 Gy (EQD2, α/β = 3 Gy). Taking place brachytherapy all patients received the simultaneous integrated focal boost to the intra-prostatic tumor lesions visible in computer-aided ultrasonography (HistoScanning™) - up to a total dose of 108-119 Gy (EQD2, α/β = 3 Gy). The primary endpoint was toxicity. Secondary endpoints were cumulative freedom from local recurrence, PSA-free survival, distant metastases-free survival, and overall survival. This trial is registered with ClinicalTrials.gov, number NCT01409876.

RESULTS

Median follow-up was 65 months. Late toxicity was generally low with only four patients scoring urinary grade 3 toxicity (4/101, 4%). Occurrence of any grade of late rectal toxicities was very low. We did not register any grade ≥2 of late rectal toxicities. The cumulative 5 years local recurrence rate (LRR) for all patients was 1%. Five years- biochemical disease-free survival estimates according Kaplan-Meier were 98,1% and 81,3% for low-/intermediate-risk and high-risk patients, respectively. Five years metastases-free survival estimates according Kaplan-Meier were 98,0% and 83,3% for all patients, low-/intermediate-risk and high-risk patients, respectively.

CONCLUSIONS

The 5 years-results from this Phase II Trial show that focal dose escalation with computer-aided ultrasonography and brachytherapy for patients with non-metastatic prostate cancer is safe and effective.

Rectal Radiation Dose and Clinical Outcomes in Prostate Cancer Patients Treated With Stereotactic Body Radiation Therapy With and Without Hydrogel

Background

Patients with prostate cancer treated with stereotactic body radiation therapy (SBRT) may experience gastrointestinal (GI) toxicity. The hydrogel may mitigate this toxicity by reducing the rectal radiation dose. The purpose of this study is to compare rectal radiation dose and GI toxicity in patients receiving prostate SBRT with and without hydrogel.

Methods

Consecutive patients treated with SBRT between February 2017 and January 2020 with and without hydrogel were retrospectively identified. Baseline characteristics including prostate volume, rectal diameter, body mass index (BMI), age, pretreatment prostate-specific antigen (PSA), Gleason score, T-stage, and androgen deprivation therapy (ADT) usage were compared. Dosimetric outcomes (V40Gy, V36Gy, V32Gy, V38Gy, and V20Gy), rates of acute (≤90 days) and late (>90 days) GI toxicity, and PSA outcomes were evaluated for patients with and without hydrogel.

Results

A total of 92 patients were identified (51 hydrogel and 41 non-hydrogel). There were no significant differences in baseline characteristics. Rectal V38(cc) was significantly less in the hydrogel group (mean 0.44 vs. mean 1.41 cc, p = 0.0002), and the proportion of patients with V38(cc) < 2 cc was greater in the hydrogel group (92% vs. 72%, p = 0.01). Rectal dose was significantly lower for all institutional dose constraints in the hydrogel group (p < 0.001). The hydrogel group experienced significantly less acute overall GI toxicity (16% hydrogel vs. 28% non-hydrogel, p = 0.006), while the difference in late GI toxicity trended lower with hydrogel but was not statistically significant (4% hydrogel vs. 10% non-hydrogel, p = 0.219). At a median follow-up of 14.8 months, there were no biochemical recurrences in either group.

Conclusion

Hydrogel reduces rectal radiation dose in patients receiving prostate SBRT and is associated with a decreased rate of acute GI toxicity.

Combined hyperthermia and radiotherapy for prostate cancer: a systematic review

Optimization of treatment strategies for prostate cancer patients treated with curative radiation therapy (RT) represents one of the major challenges for the radiation oncologist. Dose escalation or combination of RT with systemic therapies is used to improve tumor control in patients with unfavorable prostate cancer, at the risk of increasing rates and severity of treatment-related toxicities. Elevation of temperature to a supra-physiological level has been shown to both increase tumor oxygenation and reduce DNA repair capabilities. Thus, hyperthermia (HT) combined with RT represents a compelling treatment strategy to improve the therapeutic ratio in prostate cancer patients. The aim of the present systematic review is to report on preclinical and clinical evidence supporting the combination of HT and RT for prostate cancer, discussing future applications and developments of this combined treatment.

Conventional dose versus dose escalated radiotherapy including high-dose-rate brachytherapy boost for patients with Gleason score 9-10 clinical localized prostate cancer

As several recent researches focus on the importance of Gleason 9-10, we examine the role of radiotherapy dose escalation in those patients. We analyzed 476 patients with Gleason score 9-10 prostate cancer treated with radiotherapy. Of them, 127 patients were treated with conventional-dose external beam radiotherapy (Conv RT) and 349 patients were treated with high-dose radiotherapy (HDRT; 249 patients received high-dose-rate brachytherapy boost + external beam radiotherapy [HDR boost] and 100 patients received intensity-modulated radiotherapy [IMRT]). We compared these treatment groups using multi-institutional retrospective data. The patients had a median follow-up period of 66.3 months. HDRT showed superior biochemical disease-free survival (bDFS) rate (85.2%; HDR boost 84.7% and IMRT 86.6%) to Conv RT (71.1%, p < 0.0001) at 5 years, with a hazard ratio of 0.448. There were borderline difference in prostate cancer-specific mortality (PCSM; 4.3% and 2.75%, p = 0.0581), and distant metastasis-free survival (DMFS; 94.4% and 89.6%, p = 0.0916) rates at 5-years between Conv RT and HDRT group. Dose escalated radiotherapy showed better bDFS, borderline improvement in PCSM, and equivocal outcome in DMFS in with clinically localized Gleason 9-10 prostate cancer.

Prostate deformation during hypofractionated radiotherapy: an analysis of implanted fiducial marker displacement

BACKGROUND

To report prostate deformation during treatment, based on an analysis of fiducial marker positional differences in a large sample.

MATERIAL AND METHODS

This study included 144 patients treated with prostate stereotactic body radiation therapy after implantation in each of 4 gold fiducial markers (FMs), which were located and numbered consistently. The center of mass of the FMs was recorded for every pair of X-ray images taken during treatment. The distance between each pair of fiducials in the live X-ray images is calculated and compared with the respective distances as determined in the CT volume. The RBE is the difference between these distances. Mean RBE and intrafraction and interfraction RBE were evaluated. The intrafraction and intefraction RBE variability were defined as the standard deviation, respectively, of all RBE during 1 treatment fraction and of the mean daily RBE over the whole treatment course.

RESULTS

We analyzed 720 treatment fractions comprising 24,453 orthogonal X-ray image acquisitions. We observed a trend to higher RBE related to FM4 (apex) during treatment. The fiducial marker in the prostate apex could not be used in 16% of observations, in which RBE was > 2.5 mm. The mean RBEavg was 0.93 ± 0.39 mm (range 0.32-1.79 mm) over the 5 fractions. The RBEavg was significantly lower for the first and second fraction compared with the others (P < .001). The interfraction variability of RBEavg was 0.26 ± 0.16 mm (range 0.04-0.74 mm). The mean intrafraction variability of all FMs was 0.45 ± 0.25 mm. The highest Pearson correlation coefficient was observed between FM2 and FM3 (middle left and right prostate) (R = 0.78; P < .001). Every combination with FM4 yielded lower coefficients (range 0.66-0.71; P < .001), indicating different deformation of the prostate apex.

CONCLUSIONS

Ideally, prostate deformation is generally small, but it is very sensitive to rectal and bladder filling. We observed RBE up to 11.3 mm. The overall correlation between FMs was affected by shifts of individual fiducials, indicating that the prostate is not a "rigid" organ. Systematic change of RBE average between subsequent fractions indicates a systematic change in prostate shape.

Separation effect and development of implantation technique of hydrogel spacer for prostate cancers

PURPOSE

The purpose was to improve the placement of a hydrogel spacer in prostate cancer patients receiving radiotherapy.

METHODS AND MATERIALS

One hundred and sixty patients with prostate cancer were classified into 3 groups as follows: group 1, no spacer (n = 30); group 2, spacer placed using conventional technique (n = 100); and group 3, spacer placed using new technique (n = 30). When placing the spacer, the tip of the needle was placed at the middle of the prostate gland (group 2) or at a level corresponding to a cranial:caudal ratio of 6:4 and as close to the prostate gland as possible (group 3). The separation effect was then examined and compared among the groups.

RESULTS

The separation in group 2 was larger than that in group 1 from the base to the apex (4 mm) level of the prostate, while the separation in group 3 was larger than that in group 2 from the middle to the apex (4 mm) level of the prostate. The separation values for the middle to the apex, the spacer thickness from the apex (10 mm) level to the apex, the rectal exclusion from the middle to the apex, and the laterality were correlated with the 50 and 60 Gray relative biological effectiveness (Gy(RBE)) rectal dose (p = 4.1 × 10^-9 - 0.046). The separation vales were strongly correlated with the spacer thickness at the apex (10 mm) and apex (4 mm) (p = 1.1 × 10^-18 - 1.8 × 10^-17). The rectal volumes at 10-60 Gy(RBE) differed among the groups (p = 5.1 × 10^-19 - 5.4 × 10^-3). The rectal volumes in group 2 were smaller than those in group 1 at all dose levels, while those in group 3 were smaller than those in group 2 at dose levels of 30-50 Gy(RBE).

CONCLUSIONS

The separation, spacer thickness and rectal exclusion from the middle to the apex of the prostate and the laterality of the hydrogel spacer affected the reduction in the rectal dose. The rectal dose can be further reduced by implanting a spacer on the caudal and the prostate side.

Clinical Efficacy and Safety of Proton and Carbon Ion Radiotherapy for Prostate Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Carbon ion radiotherapy (CIRT) and proton beam therapy (PBT) are promising methods for prostate cancer, however, the consensus of an increasing number of studies has not been reached. We aimed to provide systematic evidence for evaluating the efficacy and safety of CIRT and PBT for prostate cancer by comparing photon radiotherapy.

MATERIALS AND METHODS

We searched for studies focusing on CIRT and PBT for prostate cancer in four online databases until July 2021. Two independent reviewers assessed the quality of included studies and used the GRADE approach to rate the quality of evidence. R 4.0.2 software was used to conduct the meta-analysis. A meta-regression test was performed based on the study design and tumor stage of each study.

RESULTS

A total of 33 studies including 13 CIRT- and 20 PBT-related publications, involving 54,101, participants were included. The quality of the included studies was found to be either low or moderate quality. Random model single-arm meta-analysis showed that both the CIRT and PBT have favorable efficacy and safety, with similar 5-year overall survival (OS) (94 vs 92%), the incidence of grade 2 or greater acute genitourinary (AGU) toxicity (5 vs 13%), late genitourinary (LGU) toxicity (4 vs 5%), acute gastrointestinal (AGI) toxicity (1 vs 1%), and late gastrointestinal (LGI) toxicity (2 vs 4%). However, compared with CIRT and PBT, photon radiotherapy was associated with lower 5-year OS (72-73%) and a higher incidence of grade 2 or greater AGU (28-29%), LGU (13-14%), AGI (14-19%), and LGI toxicity (8-10%). The meta-analysis showed the 3-, 4-, and 5-year local control rate (LCR) of CIRT for prostate cancer was 98, 97, and 99%; the 3-, 4-, 5-, and 8-year biochemical relapse-free rate (BRF) was 92, 91, 89, and 79%. GRADE assessment results indicated that the certainty of the evidence was very low. Meta-regression results did not show a significant relationship based on the variables studied (P<0.05).

CONCLUSIONS

Currently available evidence demonstrated that the efficacy and safety of CIRT and PBT for prostate cancer were similar, and they may significantly improve the OS, LCR, and reduce the incidence of GU and GI toxicity compared with photon radiotherapy. However, the quantity and quality of the available evidence are insufficient. More high-quality controlled studies are needed in the future.

The Journey of Radiotherapy Dose Escalation in High Risk Prostate Cancer; Conventional Dose Escalation to Stereotactic Body Radiotherapy (SBRT) Boost Treatments

High risk prostate cancer (HR-PrCa) is a subset of localized PrCa with significant potential for morbidity and mortality associated with disease recurrence and metastasis. Radiotherapy combined with Androgen Deprivation Therapy has been the standard of care for many years in HR-PrCa. In recent years, dose escalation, hypo-fractionation and high precision delivery with immobilization and image-guidance have substantially changed the face of modern PrCa radiotherapy, improving treatment convenience and outcomes. Ultra-hypo-fractionated radiotherapy delivered with high precision in the form of stereotactic body radiation therapy (SBRT) combines delivery of high biologically equivalent dose radiotherapy with the convenience of a shorter treatment schedule, as well as the promise of similar efficacy and reduced toxicity compared to conventional radiotherapy. However, rigorous investigation of SBRT in HR-PrCa remains limited. Here, we review the changes in HR-PrCa radiotherapy through dose escalation, hypo- and ultra-hypo-fractionated radiotherapy boost treatments, and the radiobiological basis of these treatments. We focus on completed and on-going trials in this disease utilizing SBRT as a sole radiation modality or as boost therapy following pelvic radiation.

Dosimetric analysis of three-dimensional conformal radiotherapy, intensity-modulated radiotherapy-step and shoot, helical tomotherapy, and volumetric modulated arc therapy in prostate cancer radiotherapy

Introduction

There is limited study comparing dosimetry parameters in detail. In regard to prostate cancer, there are four different techniques, namely three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy-step and shoot (IMRT-SS), IMRT-helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT).

Materials and Methods

Experimental study with intervention on ten prostate cancer patients' computed tomography planning data. 78 Gy dose in 39 fractions was given for planning target volume.Experimental study with intervention on ten prostate cancer patients' computed tomography planning data. 78 Gy dose in 39 fractions was given for planning target volume.

Results

The mean V75 Gy rectum and bladder between 3D-CRT and the other three abovementioned techniques all showed significant results (P < 0.05). V5 Gy remaining volume at risk (RVR) between 3D-CRT versus VMAT and HT, IMRT-SS versus HT, and VMAT versus HT is statistically significant (P < 0.0001). The longest radiation time was done with HT (mean 4.70 ± 0.84 min).

Conclusion

V75 Gy rectum bladder between 3D-CRT techniques differ significantly compared to the three other techniques and may not be suitable to the implementation of escalation doses. The HT technique produced the highest V5 Gy RVR and needed the highest monitor unit amount and the longest radiation duration. The VMAT technique was considered capable of realizing dose escalation in prostate cancer radiotherapy by minimizing toxicity in the rectum and bladder with the shortest radiation duration.

A Review on the Current Treatment Paradigm in High-Risk Prostate Cancer

High-risk prostate cancer is traditionally treated with a combination of radiotherapy (RT) and androgen deprivation therapy (ADT). However, recent advancements in systemic treatment and radiotherapy have widened the spectrum of treatment for this patient population. Use of image guidance and intensity modulation, as well as the incorporation of brachytherapy, has led to safe radiotherapy dose escalation with reduced risk of recurrence. Clinical trials have helped define the role of pelvic nodal radiotherapy, the role of stereotactic ablative radiotherapy, and the optimal duration and sequencing of ADT in combination with radiotherapy. Emerging evidence has redefined the role of surgery in this cohort. Contemporary clinical trials have identified new systemic therapy options in high-risk prostate cancer. Finally, new imaging modalities including multi-parametric MRI and molecular imaging and genomic classifiers have ushered a new era in patient selection, risk stratification, and treatment tailoring.

Highly hypofractionated intensity-modulated radiation therapy for nonmetastatic prostate cancer with a simultaneous integrated boost to intraprostatic lesions: a planning study

PURPOSE

The purpose of this planning study was to develop an acceptable technique for highly hypofractionated intensity-modulated radiation therapy using simultaneous integrated boost technique (SIB-hHF-RT) for nonmetastatic National Comprehensive Cancer Network high-risk prostate cancer.

MATERIALS AND METHODS

We created SIB-hHF-RT plans for 14 nonmetastatic prostate cancer patients with MRI-detectable intraprostatic lesions (IPLs) and without intestines locating close to the seminal vesicle and prostate. We prescribed 57 Gy for IPLs and 54 Gy for the remainder of planning target volume (PTV) in 15 fractions. The IPLs were contoured based on magnetic resonance imaging, and PTV was generated by adding 6-8-mm margins to the clinical target volume. For the dose-volume constraints of organs at risk (OARs), the same constraints as 54 Gy plans were used so as not to increase the toxicity.

RESULTS

All created plans fulfilled the dose-volume constraints of all targets and OARs. The median estimated beam-on time was 108.5 s. For patient-specific quality assurance, the global gamma passing rates (3%/2 mm) with 10% dose threshold criteria were greater than 93% in all cases and greater than 95% in 11 cases.

CONCLUSION

SIB-hHF-RT plans were developed that fulfill the acceptable dose-volume constraints and pass patient-specific quality assurance. We believe these plans can be applied to selected patients with nonmetastatic prostate cancer.

Towards real-time PGS range monitoring in proton therapy of prostate cancer

Proton therapy of prostate cancer (PCPT) was linked with increased levels of gastrointestinal toxicity in its early use compared to intensity-modulated radiation therapy (IMRT). The higher radiation dose to the rectum by proton beams is mainly due to anatomical variations. Here, we demonstrate an approach to monitor rectal radiation exposure in PCPT based on prompt gamma spectroscopy (PGS). Endorectal balloons (ERBs) are used to stabilize prostate movement during radiotherapy. These ERBs are usually filled with water. However, other water solutions containing elements with higher atomic numbers, such as silicon, may enable the use of PGS to monitor the radiation exposure of the rectum. Protons hitting silicon atoms emit prompt gamma rays with a specific energy of 1.78 MeV, which can be used to monitor whether the ERB is being hit. In a binary approach, we search the silicon energy peaks for every irradiated prostate region. We demonstrate this technique for both single-spot irradiation and real treatment plans. Real-time feedback based on the ERB being hit column-wise is feasible and would allow clinicians to decide whether to adapt or continue treatment. This technique may be extended to other cancer types and organs at risk, such as the oesophagus.

High-dose-rate brachytherapy for prostate cancer: Rationale, current applications, and clinical outcome

Background

High‐dose‐rate brachytherapy (HDR BRT) has been enjoying rapid acceptance as a treatment modality offered to selected prostate cancer patients devoid of risk group, employed either in monotherapy setting or combined with external beam radiation therapy (EBRT) and is currently one of the most active clinical research areas.

Recent findings

This review encompasses all the current evidence to support the use of HDR BRT in various clinical scenario and shines light to the HDR BRT rationale, as an ultimately conformal dose delivery method enabling safe dose escalation to the prostate.

Conclusion

Valid long‐term data, both in regard to the oncologic outcomes and toxicity profile, support the current clinical indication spectrum of HDR BRT. At the same time, this serves as solid, rigid ground for emerging therapeutic applications, allowing the technique to remain in the spotlight alongside stereotactic radiosurgery.

How Has Prostate Cancer Radiotherapy Changed in Italy between 2004 and 2011? An Analysis of the National Patterns-Of-Practice (POP) Database by the Uro-Oncology Study Group of the Italian Society of Radiotherapy and Clinical Oncology (AIRO)

Simple Summary

This is a safety and efficacy analysis from a very large dataset of patients affected by localized prostate cancer having received radiotherapy with or without concomitant androgen deprivation therapy in twelve academic and non-academic Italian Institutions. The aim of this retrospective "real life" study was to provide additional data on clinical presentation, diagnostic workup, radiation therapy management and toxicity as collected within the framework of POP III. Though the usual limitations for a retrospective analysis apply, it nevertheless may expand the current knowledge in this area showing the progress of radiation therapy techniques and clinical outcomes in the period between 2004 and 2011 after a significant period of follow up.

Abstract

Background and purpose: Two previous “Patterns Of Practice” surveys (POP I and POP II), including more than 4000 patients affected by prostate cancer treated with radical external beam radiotherapy (EBRT) between 1980 and 2003, established a “benchmark” Italian data source for prostate cancer radiotherapy. This report (POP III) updates the previous studies. Methods: Data on clinical management and outcome of 2525 prostate cancer patients treated by EBRT from 2004 to 2011 were collected and compared with POP II and, when feasible, also with POP I. This report provides data on clinical presentation, diagnostic workup, radiation therapy management, and toxicity as collected within the framework of POP III. Results: More than 50% of POP III patients were classified as low or intermediate risk using D’Amico risk categories as in POP II; 46% were classified as ISUP grade group 1. CT scan, bone scan, and endorectal ultrasound were less frequently prescribed. Dose-escalated radiotherapy (RT), intensity modulated radiotherapy (IMRT), image guided radiotherapy (IGRT), and hypofractionated RT were more frequently offered during the study period. Treatment was commonly well tolerated. Acute toxicity improved compared to the previous series; late toxicity was influenced by prescribed dose and treatment technique. Five-year overall survival, biochemical relapse free survival (BRFS), and disease specific survival were similar to those of the previous series (POP II). BRFS was better in intermediate- and high-risk patients treated with ≥ 76 Gy. Conclusions: This report highlights the improvements in radiotherapy planning and dose delivery among Italian Centers in the 2004–2011 period. Dose-escalated treatments resulted in better biochemical control with a reduction in acute toxicity and higher but acceptable late toxicity, as not yet comprehensively associated with IMRT/IGRT. CTV-PTV margins >8 mm were associated with increased toxicity, again suggesting that IGRT—allowing for tighter margins—would reduce toxicity for dose escalated RT. These conclusions confirm the data obtained from randomized controlled studies.

Low-/high-dose-rate brachytherapy boost in patients with intermediate-risk prostate cancer treated with radiotherapy: long-term results from a single institution team experience

Purpose

To compare brachytherapy (BT) boost of low-dose-rate (LDR) and high-dose-rate (HDR) techniques in patients diagnosed with intermediate-risk prostate cancer.

Material and methods

Between January 2005 and February 2018, 142 patients (50 LDR and 92 HDR) with intermediate-risk prostate cancer were treated with a BT boost, and retrospectively analyzed. Prescribed dose was 45 Gy with external beam radiotherapy (EBRT) plus 100-108 Gy with LDR-BT, and 60 Gy with EBRT plus one fraction of 10 Gy with HDR-BT. 99% of patients received androgen deprivation therapy (ADT) for 6 months. Primary endpoint was to compare LDR and HDR boosts in terms of biochemical progression-free survival (bPFS). Secondary endpoint, after re-classifying patients into "favorable" and "unfavorable" sub-groups, was to analyze differences with a similar treatment intensity.

Results

Median overall follow-up for the total cohort was 66.5 months (range, 16-185 months). There were no significant differences in bPFS, overall survival, cause specific survival, local failure, lymph node failure, or distant failure when LDR or HDR was employed. bPFS at 90 months was 100% for favorable, and 89% and 85% for unfavorable patients at 60 months and 90 months, respectively (log-rank test, p = 0.017). The crude incidence of genitourinary acute and chronic toxicity grade 3 was 0.7% and 4%, respectively. Twelve patients (8%) had chronic rectal hemorrhage grade 2, in whom argon was applied (4 LDR and 8 HDR).

Conclusions

Combined treatment is an excellent therapeutic option in patients with intermediate-risk prostate carcinoma, with similar results in both LDR and HDR approaches and very low toxicities. Importantly, the current literature has indicated that unfavorable-risk patients belong to a different category, and should be treated as patients with high-risk factors. Therefore, the stratification and identification of both risk groups is extremely relevant.

Radiotherapy for Clinically Localized T3b or T4 Very-High-Risk Prostate Cancer-Role of Dose Escalation Using High-Dose-Rate Brachytherapy Boost or High Dose Intensity Modulated Radiotherapy

Simple Summary

Recently, high-risk prostate cancer was subdivided to a very-high-risk group considered to have the worst prognosis, including clinical stage T3b–T4, primary Gleason pattern 5, or more than four biopsy cores with Gleason score 8–10. Among these, T3b–T4 stage is a special interest in radiotherapy because of their wider target volume outside the prostate. We examined this subgroup and found that dose escalation in radiotherapy both with brachytherapy or intensity modulated radiotherapy (IMRT) improved biochemical free survival rate but not in prostate cancer specific survival rate and overall survival rate.

Abstract

To examine the efficacy of dose escalating radiotherapy into patients with cT3b or T4 localized prostate cancer, we compared Group A (86 conventional dose external beam radiotherapy: EBRT group, treated with 70–72 Gy) and group B (39 high dose EBRT group (HDEBRT group, 74–80 Gy) and 124 high-dose-rate brachytherapy (HDR) + EBRT (HDR boost)) using multi-institutional retrospective data. The actuarial 5-year biochemical disease-free survival (bDFS) rate, prostate cancer specific survival rate (PSS), and overall survival rate (OS) were 75.8%, 96.8%, and 93.5%. Group B showed superior 5-year bDFS rate (81.2%) as compared to the group A (66.5%) (p < 0.0001) with a hazard ratio of 0.397. Equivocal 5-year PSS (98.3% and 94.8% in group B and group A) and OS (both 93.7%) were found between those groups. Accumulated late grade ≥ 2 toxicities in gastrointestinal and genitourinary tracts were similar among those three groups. Therefore, both HDEBRT and HDR boost could be good options for improving the bDFS rate in cT3–T4 localized prostate cancer without affecting PSS and OS.

Feeding the Controversy: When Pelvic Irradiation Improves Outcomes in High-Risk and Very High-Risk Prostate Cancer

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

Robust treatment planning of dose painting for prostate cancer based on ADC-to-Gleason score mappings - what is the potential to increase the tumor control probability?

BACKGROUND AND PURPOSE

The aim of this study was to evaluate the potential to increase the tumor control probability (TCP) with 'dose painting by numbers' (DPBN) plans optimized in a treatment planning system (TPS) compared to uniform dose plans. The DPBN optimization was based on our earlier published formalism for prostate cancer that is driven by dose-responses of Gleason scores mapped from apparent diffusion coefficients (ADC).

MATERIAL AND METHODS

For 17 included patients, a set of DPBN plans were optimized in a TPS by maximizing the TCP for an equal average dose to the prostate volume (CTVT) as for a conventional uniform dose treatment. For the plan optimizations we applied different photon energies, different precisions for the ADC-to-Gleason mappings, and different CTVT positioning uncertainties. The TCP increasing potential was evaluated by the DPBN efficiency, defined as the ratio of TCP increases for DPBN plans by TCP increases for ideal DPBN prescriptions (optimized without considering radiation transport phenomena, uncertainties of the CTVT positioning, and uncertainties of the ADC-to-Gleason mapping).

RESULTS

The median DPBN efficiency for the most conservative planning scenario optimized with a low precision ADC-to-Gleason mapping, and a positioning uncertainty of 0.6 cm was 10%, meaning that more than half of the patients had a TCP gain of at least 10% of the TCP for an ideal DPBN prescription. By increasing the precision of the ADC-to-Gleason mapping, and decreasing the positioning uncertainty the median DPBN efficiency increased by up to 40%.

CONCLUSIONS

TCP increases with DPBN plans optimized in a TPS were found more likely with a high precision mapping of image data into dose-responses and a high certainty of the tumor positioning. These findings motivate further development to ensure precise mappings of image data into dose-responses and to ensure a high spatial certainty of the tumor positioning when implementing DPBN clinically.

Focal Boost to the Intraprostatic Tumor in External Beam Radiotherapy for Patients With Localized Prostate Cancer: Results From the FLAME Randomized Phase III Trial

PURPOSE

This study investigates whether focal boosting of the macroscopic visible tumor with external beam radiotherapy increases biochemical disease-free survival (bDFS) in patients with localized prostate cancer.

PATIENTS AND METHODS

In the phase III, multicenter, randomized controlled Focal Lesion Ablative Microboost in Prostate Cancer trial, 571 patients with intermediate- and high-risk prostate cancer were enrolled between 2009 and 2015. Patients assigned to standard treatment received 77 Gy (fractions of 2.2 Gy) to the entire prostate. The focal boost arm received an additional simultaneous integrated focal boost up to 95 Gy (fractions up to 2.7 Gy) to the intraprostatic lesion visible on multiparametric magnetic resonance imaging. Organ at risk constraints were prioritized over the focal boost dose. The primary end point was 5-year bDFS. Secondary end points were disease-free survival (DFS), distant metastases-free survival, prostate cancer-specific survival, overall survival, toxicity, and health-related quality of life.

RESULTS

Median follow-up was 72 months. Biochemical DFS was significantly higher in the focal boost compared with the standard arm (hazard ratio 0.45, 95% CI, 0.28 to 0.71, P < .001). At 5-year follow-up bDFS was 92% and 85%, respectively. We did not observe differences in prostate cancer-specific survival (P = .49) and overall survival (P = .50). The cumulative incidence of late genitourinary and GI toxicity grade ≥ 2 was 23% and 12% in the standard arm versus 28% and 13% in the focal boost arm, respectively. Both for late toxicity as health-related quality of life, differences were small and not statistically significant.

CONCLUSION

The addition of a focal boost to the intraprostatic lesion improved bDFS for patients with localized intermediate- and high-risk prostate cancer without impacting toxicity and quality of life. The Focal Lesion Ablative Microboost in Prostate Cancer study shows that a high focal boost strategy to improve tumor control while respecting organ at risk dose constraints is effective and safe.

Evaluación de Errores de Posicionamiento en los 6 Grados de Libertad en Pacientes con Cáncer de próstata tratados con radioterapia

Objetivos Determinar la magnitud de los errores de posicionamiento en los 6 grados de libertad y calcular el Margen a CTV para un protocolo adaptado en pacientes con cáncer de próstata temprano y localmente avanzado en un centro de referencia en Colombia.

Métodos Se realizó un estudio observacional prospectivo en 61 pacientes con cáncer de próstata tratados con radioterapia en el Centro Javeriano de Oncología del Hospital Universitario San Ignacio durante el 2018, con toma de imágenes volumétricas de rayos x durante los primeros 3 días de tratamiento obteniéndose un promedio en errores traslacionales y rotacionales. Posteriormente se tomaron imágenes semanales. Además, se realizó el cálculo del margen al PTV y variaciones en vejiga y recto durante el tratamiento.

Resultados Un total de 508 imágenes fueron registradas durante las 8 semanas de tratamiento, los errores traslacionales y rotacionales tuvieron un comportamiento alrededor de cero sin diferencias significativas inclusive en pacientes con IMC > = 25. También se calculó el margen al PTV encontrándose entre 5 y 8 mm, en cuanto a las medidas de vejiga y recto no se encontraron diferencias estadísticamente significativas en las imágenes adquiridas durante la radioterapia.

Conclusiones De acuerdo a los datos encontrados en este estudio, una adecuada reproducibilidad en paciente con cáncer de próstata puede ser encontrada usando el método de registro rígido de la anatomía pélvica ósea, promediando las 3 primeras imágenes y posteriormente con imágenes semanales, en centros con alta demanda de pacientes garantizando así una adecuada precisión del tratamiento.

Predicting Radiotherapy Impact on Late Bladder Toxicity in Prostate Cancer Patients: An Observational Study

BACKGROUND AND PURPOSE

The aim of our study was to elaborate a suitable model on bladder late toxicity in prostate cancer (PC) patients treated by radiotherapy with volumetric technique.

MATERIALS AND METHODS

PC patients treated between September 2010 and April 2017 were included in the analysis. An observational study was performed collecting late toxicity data of any grade, according to RTOG and CTCAE 4.03 scales, cumulative dose volumes histograms were exported for each patient. Vdose, the value of dose to a specific volume of organ at risk (OAR), impact was analyzed through the Mann-Whitney rank-sum test. Logistic regression was used as the final model. The model performance was estimated by taking 1000 samples with replacement from the original dataset and calculating the AUC average. In addition, the calibration plot (Hosmer-Lemeshow goodness-of-fit test) was used to evaluate the performance of internal validation. RStudio Software version 3.3.1 and an in house developed software package "Moddicom" were used.

RESULTS

Data from 175 patients were collected. The median follow-up was 39 months (min-max 3.00-113.00). We performed Mann-Whitney rank-sum test with continuity correction in the subset of patients with late bladder toxicity grade ≥ 2: a statistically significant p-value with a Vdose of 51.43 Gy by applying a logistic regression model (coefficient 4.3, p value 0.025) for the prediction of the development of late G ≥ 2 GU toxicity was observed. The performance for the model's internal validation was evaluated, with an AUC equal to 0.626. Accuracy was estimated through the elaboration of a calibration plot.

CONCLUSIONS

Our preliminary results could help to optimize treatment planning procedures and customize treatments.

Ultrasound-guided transrectal implantation of fiducial markers for image-guided radiotherapy of prostate cancer without local anesthesia: Patient-reported gastrointestinal-genitourinary system complications and pain

Purpose

The present study evaluates procedure-associated pain and side effects in the gastrointestinal-genitourinary system in patients with early-stage prostate cancer who were treated with image-guided radiotherapy (IGRT), accompanied by an ultrasound-guided transrectal implantation of fiducial markers, without local anesthesia.

Materials and Methods

A total of 46 patients who referred to our clinics between 2012 and 2017 with a diagnosis of early-stage prostate cancer were included in the study. Before undergoing radiotherapy, all patients were implanted with three intraprostatic fiducial markers through the ultrasound-guided transrectal approach without local anesthesia. The patients underwent radiotherapy after the clinical target volumes were established, in accordance with the respective risk groups, and localization of the markers was confirmed before each therapy session. The levels of procedure-associated pain and side effects were graded immediately after the procedure through the use of a patient-based scoring system.

Results

The faces pain scale - revised version was used for the measurement of the severity of procedure-associated pain. Of the total study sample, the facial expressions of 38 patients (35%) corresponded to level 0 in the study, seven (15%) to level 2, and a single patient (2%) to level 4. None of the facial expressions of the patients corresponded to levels 6, 8, or 10. The evaluation of procedure-related genitourinary and gastrointestinal system side effects indicated that nine patients (20%) experienced side effects, while no side effects were reported in 37 patients (80%). The reported side effects included rectal bleeding in two patients (4%), dysuria in three patients (6%), hematuria in five patients (11%), and frequent urination in five patients (11%). None of the patients experienced fever or hematospermia. All side effects were reported by the respondents as "a little," while only one patient answered positively to the question on the frequency of urination. Among the patients who answered "yes" and "a little" to the questions evaluating genitourinary and gastrointestinal system side effects, the severity of these events was reported as Grade 1, corresponding to mild adverse, in only 9 (20%) patients. None of the patients experienced a Grade 2 or higher severe adverse event. In the comparison of the severity of pain of the patients during the fiducial marker procedure without local anesthesia with the severity of pain during the biopsy, 24 patients (80%) reported "lower" levels of pain, while five patients (20%) reported "equal" levels of pain. None of the patients stated that they had experienced "more" pain.

Conclusion

IGRT accompanied by an ultrasound-guided implantation of fiducial markers without local anesthesia can be considered a safe method, given the associated acceptable levels of pain, low side effect profiles, and high prostate-specific antigen control rates.

Rectal wall sparing effect of a rectal retractor in prostate intensity-modulated radiotherapy

Purpose

The objective of the study was to evaluate the effectiveness of a rectal retractor (RR) designed to protect rectal tissue in intensity-modulated radiotherapy (IMRT) by pushing rectal wall (RW) away from the prostate.

Materials and Methods

Twelve patients with localized prostate cancer were enrolled into this study. Patients underwent two computed tomography (CT) scans without and with RR. A prescription of 80 Gy in 40 fractions was planned on CT scans with and without RR. This study evaluates the ability of the RR in RW dose reduction, in particular reduction of the RW V_70Gy≥ 25% in comparison with the plan without RR dose-volume histograms were generated with and without RR. The patient's tolerance was assessed by patient-reported outcomes.

Results

The planning target volume coverage was equal for both without and with RR (P = 0.155). The mean dose to the RW was statistically significantly lower for the plan with RR than that for the plan without RR, a mean reduction of 5.8 Gy (P = 0.003). Significant relative reductions in rectal dose-volume parameters whether in absolute volume (cc) or as a percentage of contoured RW were detected. A relative reduction more than 25% in RW V_70Gy(%) in 100% of patients was achieved. The rectal retraction resulted in a significant increase in the prostate to the rectum space at the prostate midgland level, an absolute increase of 2.7 mm. The retraction of the rectum induced a mean (±standard deviation) pain score of 2.7 (±1.3) according to the visual analog score.

Conclusion

The application of a RR showed a remarkable rectal sparing effect during prostate IMRT. This may lead to reduced acute and late rectal toxicities in prostate IMRT.

Magnetic resonance image-guided adaptive stereotactic body radiotherapy for prostate cancer: preliminary results of outcome and toxicity

OBJECTIVE

Using moderate or ultra-hypofractionation, which is also known as stereotactic body radiotherapy (SBRT) for treatment of localized prostate cancer patients has been increased. We present our preliminary results on the clinical utilization of MRI-guided adaptive radiotherapy (MRgRT) for prostate cancer patients with the workflow, dosimetric parameters, toxicities and prostate-specific antigen (PSA) response.

METHODS

50 prostate cancer patients treated with ultra-hypofractionation were included in the study. Treatment was performed with intensity-modulated radiation therapy (step and shoot) technique and daily plan adaptation using MRgRT. The SBRT consisted of 36.25 Gy in 5 fractions with a 7.25 Gy fraction size. The time for workflow steps was documented. Patients were followed for the acute and late toxicities and PSA response.

RESULTS

The median follow-up for our cohort was 10 months (range between 3 and 29 months). The median age was 73.5 years (range between 50 and 84 years). MRgRT was well tolerated by all patients. Acute genitourinary (GU) toxicity rate of Grade 1 and Grade 2 was 28 and 36%, respectively. Only 6% of patients had acute Grade 1 gastrointestinal (GI) toxicity and there was no Grade ≥ 2 GI toxicity. To date, late Grade 1 GU toxicity was experienced by 24% of patients, 2% of patients experienced Grade 2 GU toxicity and 6% of patients reported Grade 2 GI toxicity. Due to the short follow-up, PSA nadir has not been reached yet in our cohort.

CONCLUSION

In conclusion, MRgRT represents a new method for delivering SBRT with markerless soft tissue visualization, online adaptive planning and real-time tracking. Our study suggests that ultra-hypofractionation has an acceptable acute and very low late toxicity profile.

ADVANCES IN KNOWLEDGE

MRgRT represents a new markerless method for delivering SBRT for localized prostate cancer providing online adaptive planning and real-time tracking and acute and late toxicity profile is acceptable.

The Role of Gold Nanorods in the Response of Prostate Cancer and Normal Prostate Cells to Ionizing Radiation-In Vitro Model

To increase the efficiency of therapy via enhancing its selectivity, the usage of gold nanorods (GNR) as a factor sensitizing cancer cells to radiation was proposed. Due to gold nanoparticles’ characteristics, the smaller doses of radiation would be sufficient in the treatment, protecting the healthy tissue around the tumor. The aim of this study was to investigate the effect of gold nanorods on cancer and normal prostate cells and the role of nanorods in the cell response to ionizing radiation. The effect was evaluated by measuring the toxicity, cell cycle, cell granularity, reactive oxygen species (ROS) level, and survival fractions. Nanorods showed a strong toxicity dependent on the concentration and incubation time toward all used cell lines. A slight effect of nanorods on the cycle distribution was observed. The results demonstrated that the administration of nanorods at higher concentrations resulted in an increased level of generated radicals. The results of cellular proliferation after irradiation are ambiguous; however, there are noticeable differences after the application of nanorods before irradiation. The obtained results lead to the conclusion that nanorods affect the physiology of both normal and cancer cells. Nanorods might become a potential tool used to increase the effectiveness of radiation treatment