Salvage Brachytherapy for Biochemically Recurrent Prostate Cancer following Primary Brachytherapy

Salvage low-dose vs high-dose brachytherapy for radio-recurrent prostate cancer

OBJECTIVE

To summarise the efficacy and toxicity of salvage low-dose-rate brachytherapy (LDR-BT) and compare these findings with the published data on salvage high-dose-rate brachytherapy (HDR-BT).

METHODS

We reviewed PubMed and EMBASE for studies published up to May 2024, mainly focusing on recurrence-free survival (RFS) with salvage LDR-BT across subgroups. We also compared RFS and adverse events with HDR-BT as a secondary objective. We reconstructed survival curves using a semi-automated tool called WebPlotDigitizer, along with a new shiny application integrated with R.

RESULTS

A total of 31 studies (891 patients) met the inclusion criteria for salvage LDR-BT. The median RFS of patients treated with salvage LDR-BT was 131.6 months, with 2-, 3- and 5-year rates of 84.6%, 74.3% and 63.5%. Lower median age (65-70 years vs 72.3-75 years, hazard ratio [HR] 0.50, 95% confidence interval [CI] 0.35-0.70; P < 0.0001) and higher adjuvant androgen deprivation therapy (ADT) proportion (83.8%-100% vs 0%-47%, HR 0.60, 95% CI 0.55-0.65; P = 0.036) were positive RFS factors. Compared to HDR-BT, salvage LDR-BT demonstrated improved RFS for all patients (HR 0.67, 95% CI 0.55-0.81; P < 0.0001). Specifically, salvage LDR-BT exhibited superior RFS (P < 0.05) for patients with a median age ≤70 years at recurrence, a median time from primary treatment to salvage therapy (TPTS) of ≥70 months, a median pre-salvage prostate-specific antigen level of ≥5 ng/mL, and a proportion of adjuvant ADT of ≥53%, compared to HDR-BT. However, LDR-BT was associated with a higher rate of severe gastrointestinal (GI; 3.5% vs 0.3%, odds ratio [OR] 0.08, 95% CI 0.03-0.28; P < 0.0001) and genitourinary (GU) toxicities (12.7% vs 5.8%, OR 0.42, 95% CI 0.30-0.60; P < 0.001) compared to HDR-BT.

CONCLUSIONS

In specific cohorts, salvage LDR-BT appears to yield superior RFS but entails a higher incidence of severe GI/GU toxicities compared to HDR-BT.

Case report of the first use of a hydrogel rectal spacer for prostate cancer reirradiation via LDR brachytherapy: applications and technical notes

Introduction

Prostate cancer remains a prevalent malignancy among men, often necessitating innovative therapeutic strategies for effective management of recurrent cases. This article examines the critical role of a biodegradable hydrogel spacer, which creates a temporary interspace between the prostate and the rectum, thus reducing radiation exposure to healthy tissues.

Case description

We present a case of a man with a history of intermediate-risk prostate adenocarcinoma initially treated with external beam radiotherapy in 2015. Despite initial remission, the patient experienced a rise in prostate-specific antigen (PSA) levels indicative of local recurrence in 2022. Salvage treatment with iodine-125 brachytherapy, preceded by the placement of a rectal spacer in January 2024, resulted in a significant reduction of PSA levels. The patient remains asymptomatic with no urinary or gastrointestinal complications 6 months after the salvage treatment.

Discussion

This case illustrates the complexities in managing recurrent prostate cancer and the evolving role of reirradiation strategies. Salvage iodine-125 brachytherapy with the placement of a rectal spacer provided precise radiation delivery while minimizing rectal toxicities. The significant biochemical response observed underscores the efficacy of this approach in controlling disease progression. The rectal spacer enhances treatment safety by reducing radiation exposure to adjacent tissues, highlighting its importance in reirradiation protocols. This case contributes to the growing evidence supporting the rectal spacer's role in enhancing the safety and efficacy of salvage brachytherapy for recurrent prostate cancer.

Conclusions

Our experience advocates for the integration of a hydrogel rectal spacer as a valuable tool in prostate cancer reirradiation protocols, offering a strategic approach to optimize treatment safety by minimizing rectal toxicity.

Feasibility of balloon rectal spacer implantation in HDR and LDR brachytherapy for prostate cancer treatment

PURPOSE

This study evaluates the use of a biodegradable balloon rectal spacer in two prostate cancer patients undergoing low dose radiation (LDR) and salvage high dose radiation (HDR) brachytherapy. The spacer aims to reduce radiation dose to adjacent organs, particularly the rectum, in patients previously treated with radiation.

METHODS

The balloon spacer was implanted transperineally under transrectal ultrasonography (TRUS) guidance in two patients. For the LDR case (73-year-old, intermediate-risk), the balloon was placed postimplant with 55 iodine-125 seeds delivering 145 Gy. For the HDR case (66-year-old, high-risk), the balloon was placed one week before treatment, which delivered 23 Gy in two weekly fractions using 16 channels.

RESULTS

The balloon provided a 14-15mm separation between rectum and prostate. In the LDR case, prostate D90 was 149.1Gy (102.83%), V100 was 91.95%, and rectum D30 was 23.93Gy (16.50%). For the HDR case, prostate D90 was 11.63Gy (105.79%), V100 was 93.63%, and rectum D0.5cc was 8.04Gy (73.15%). Both patients tolerated the treatment well, with no observed postoperative complications at 6-month follow-up.

CONCLUSIONS

The use of a rectal balloon spacer in both salvage HDR and LDR brachytherapy is feasible and safe, allowing for controlled placement and providing rectal protection from high radiation doses.

Salvage low-dose-rate brachytherapy for locally recurrent prostate cancer after definitive irradiation

Purpose

The optimal management of locally recurrent prostate cancer after definitive irradiation is still unclear but local salvage treatments are gaining interest. A retrospective, single-institution analysis of clinical outcomes and treatment-related toxicity after salvage I-125 low-dose-rate (LDR) brachytherapy (BT) for locally-recurrent prostate cancer was conducted in a Comprehensive Cancer Center.

Patients and methods

A total of 94 patients treated with salvage LDR-BT between 2006 and 2021 were included. The target volume was either the whole-gland +/- a boost on the GTV, the hemigland, or only the GTV. The prescribed dose ranged from 90 to 145 Gy. Toxicity was graded by Common Terminology Criteria for Adverse Events (CTCAE) v5.0.

Results

Median follow-up was 34 months. Initial radiotherapy was external beam radiotherapy in 73 patients (78 %) with a median dose of 76 Gy and I-125 BT in 21 patients (22 %) with a prescribed dose of 145 Gy. Median PSA at salvage was 3.75 ng/ml with a median interval between first and salvage irradiation of 9.4 years. Salvage brachytherapy was associated with androgen deprivation therapy for 32 % of the patients. Only 4 % of the patients were castrate-resistant. Failure free survival was 82 % at 2 years and 66 % at 3 years. The only factors associated with failure-free survival on multivariate analysis were hormonosensitivity at relapse and European Association of Urology (EAU) prognostic group. Late grade 3 urinary and rectal toxicities occurred in 12 % and 1 % of the patients respectively.No significant difference in toxicity or efficacy was observed between the three implant volume groups.

Conclusion

The efficacy and toxicity results are consistent with those in the LDR group of the MASTER meta-analysis. Salvage BT confirms to be an effective and safe option for locally recurrent prostate cancer. A focal approach could be interesting to reduce late severe toxicities, especially urinary.

Acute toxicity outcomes from salvage high-dose-rate brachytherapy for locally recurrent prostate cancer after prior radiotherapy

Purpose

Isolated intra-prostatic recurrence of prostate adenocarcinoma after definitive radiotherapy presents a challenging clinical scenario. Salvage options require specialized expertise and pose risks of harm. This study aimed to present the acute toxicity results from using salvage high-dose-rate brachytherapy (sHDR-BT) as treatment in locally recurrent prostate cancer cases.

Material and methods

Seventeen consecutive patients treated with sHDR-BT between 2019 and 2022 were evaluated retrospectively. Eligible patients had to have received curative intent prostate radiotherapy previously, and showed evidence of new biochemical failure. Evaluation with American Urological Association (AUA) and Common Terminology Criteria for Adverse Events (CTCAE) symptom assessments were performed for each case.

Results

The median (inter-quartile range) age prior to salvage treatment was 68 (66-74) years. The median post-sHDR-BT follow-up time was 20 (13-24) months. At baseline prior to sHDR-BT, 8 (47%) patients had significant lower urinary tract symptoms. The median AUA score prior to sHDR-BT was 7 (3-18). Three (18%) patients reported irregular bowel function and 2 (12%) reported hematochezia prior to sHDR-BT. One-month post-treatment, the median AUA score was 13 (8-21, p = 0.21). Using CTCAE scoring, there were no cases of grade 2+ bowel or rectal toxicity, and no cases of grade 3+ urinary toxicity. Reported grade 2 urinary toxicities included 10 (59%) cases of bladder spasms, 2 (12%) cases of incontinence, 1 (6%) urinary obstruction, and 4 (24%) reports of urinary urgency. All these adverse events were temporary.

Conclusions

This study adds to the existing literature by demonstrating that the acute toxicity profile of sHDR-BT is acceptable even without intra-operative magnetic resonance (MR) guidance or image registration. Further study is ongoing to determine long-term efficacy and toxicity of treatment.

Linac-based stereotactic salvage reirradiation for intraprostatic prostate cancer recurrence: toxicity and outcomes

BACKGROUND

The rates of local failure after curative radiotherapy for prostate cancer (PC) remain high despite more accurate locoregional treatments available, with one third of patients experiencing biochemical failure and clinical relapse occurring in 30-47% of cases. Today, androgen deprivation therapy (ADT) is the treatment of choice in this setting, but with not negligible toxicity and low effects on local disease. Therefore, the treatment of intraprostatic PC recurrence represents a challenge for radiation oncologists. Prostate reirradiation (Re-I) might be a therapeutic possibility. We present our series of patients treated with salvage stereotactic Re‑I for intraprostatic recurrence of PC after radical radiotherapy, with the aim of evaluating feasibility and safety of linac-based prostate Re‑I.

MATERIALS AND METHODS

We retrospectively evaluated toxicities and outcomes of patients who underwent salvage reirradiation using volumetric modulated arc therapy (VMAT) for intraprostatic PC recurrence. Inclusion criteria were age ≥ 18 years, histologically proven diagnosis of PC, salvage Re‑I for intraprostatic recurrence after primary radiotherapy for PC with curative intent, concurrent/adjuvant ADT with stereotactic body radiation therapy (SBRT) allowed, performance status ECOG 0-2, restaging choline/PSMA-PET/TC and prostate MRI after biochemical recurrence, and signed informed consent.

RESULTS

From January 2019 to April 2022, 20 patients were recruited. Median follow-up was 26.7 months (range 7-50). After SBRT, no patients were lost at follow-up and all are still alive. One- and 2‑year progression free survival (PFS) was 100% and 81.5%, respectively, while 2‑year biochemical progression-free survival (bFFS) was 88.9%. Four patients (20%) experienced locoregional lymph node progression and were treated with a further course of SBRT. Prostate reirradiation allowed the ADT start to be postponed for 12-39 months. Re‑I was well tolerated by all patients and none discontinued the treatment. No cases of ≥ G3 genitourinary (GU) or gastrointestinal (GI) toxicity were reported. Seven (35%) and 2 (10%) patients experienced acute G1 and G2 GU toxicity, respectively. Late GU toxicity was recorded in 10 (50%) patients, including 8 (40%) G1 and 2 (10%) G2. ADT-related side effects were found in 7 patients (hot flashes and asthenia).

CONCLUSION

Linac-based SBRT is a safe technique for performing Re‑I for intraprostatic recurrence after primary curative radiotherapy for PC. Future prospective, randomized studies are desirable to better understand the effectiveness of reirradiation and the still open questions in this field.

Salvage Reirradiation Options for Locally Recurrent Prostate Cancer: A Systematic Review

BACKGROUND

Reirradiation using brachytherapy (BT) and external beam radiation therapy (EBRT) are salvage strategies with locally radiorecurrent prostate cancer. This systematic review describes the oncologic and toxicity outcomes for salvage BT and EBRT [including Stereotactic Body Radiation Therapy (SBRT)].

METHODS

An International Prospective Register of Systematic Reviews (PROSPERO) registered (#211875) study was conducted using Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) guidelines. EMBASE and MEDLINE databases were searched from inception to December 2020. For BT, both low dose rate (LDR) and high dose rate (HDR) BT techniques were included. Two authors independently assessed study quality using the 18-item Modified Delphi technique.

RESULTS

A total of 39 eligible studies comprising 1967 patients were included (28 BT and 11 SBRT). In 35 studies (90%), the design was single centre and/or retrospective and no randomised prospective studies were found. Twelve BT studies used LDR only, 11 HDR only, 4 LDR or HDR and 1 pulsed-dose rate only. All EBRT studies used SBRT exclusively, four with Cyberknife alone and 7 using both Cyberknife and conventional linear accelerator treatments. Median (range) modified Delphi quality score was 15 (6-18). Median (range) follow-up was 47.5 months (13-108) (BT) and 25.4 months (21-44) (SBRT). For the LDR-BT studies, the median (range) 2-year and 5-year bRFS rates were 71% (48-89.5) and 52.5% (20-79). For the HDR-BT studies, the median (range) 2-year and 5-year bRFS rates were 74% (63-89) and 51% (45-65). For the SBRT studies, the median (range) 2-year bRFS for the SBRT group was 54.9% (40-80). Mean (range) acute and late grade≥3 GU toxicity rates for LDR-BT/HDR-BT/SBRT were 7.4%(0-14)/2%(0-14)/2.7%(0-8.7) and 13.6%(0-30)/7.9%(0-21.3%)/2.7%(0-8%). Mean (range) acute and late grade≥3 GI toxicity rates for LDR-BT/HDR-BT/SBRT were 6.5%(0-19)/0%/0.5%(0-4%) and 6.4%(0-20)/0.1%(0-0.9)/0.2%(0-1.5). One third of studies included Patient Reported Outcome Measures (PROMs).

CONCLUSIONS

Salvage reirradiation of radiorecurrent prostate cancer using HDR-BT or SBRT provides similar biochemical control and acceptable late toxicity. Salvage LDR-BT is associated with higher late GU/GI toxicity. Challenges exist in comparing BT and SBRT from inconsistencies in reporting with missing data, and prospective randomised trials are needed.

Salvage High-Dose-Rate Brachytherapy for Recurrent Prostate Cancer After Definitive Radiation

PURPOSE

Salvage high-dose-rate brachytherapy (sHDRBT) for locally recurrent prostate cancer after definitive radiation is associated with biochemical control in approximately half of patients at 3 to 5 years. Given potential toxicity, patient selection is critical. We present our institutional experience with sHDRBT and validate a recursive partitioning machines model for biochemical control.

MATERIALS AND METHODS

We performed a retrospective analysis of 129 patients who underwent whole-gland sHDRBT between 1998 and 2016. We evaluated clinical factors associated with biochemical control as well as toxicity.

RESULTS

At diagnosis the median prostate-specific antigen (PSA) was 7.77 ng/mL. A majority of patients had T1-2 (73%) and Gleason 6-7 (82%) disease; 71% received external beam radiation therapy (RT) alone, and 22% received permanent prostate implants. The median disease-free interval (DFI) was 56 months, and median presalvage PSA was 4.95 ng/mL. At sHDRBT, 46% had T3 disease and 51% had Gleason 8 to 10 disease. At a median of 68 months after sHDRBT, 3- and 5-year disease-free survival were 85% (95% CI, 79-91) and 71% (95% CI, 62-79), respectively. Median PSA nadir was 0.18 ng/mL, achieved a median of 10 months after sHDRBT. Patients with ≥35%+ cores and a DFI <4.1 years had worse biochemical control (19% vs 50%, P = .02). Local failure (with or without regional/distant failure) was seen in 11% of patients (14/129), and 14 patients (11%) developed acute urinary obstruction requiring Foley placement and 19 patients (15%) developed strictures requiring dilation.

CONCLUSIONS

sHDRBT is a reasonable option for patients with locally recurrent prostate cancer after definitive RT. Those with <35%+ cores or an initial DFI of ≥4.1 years may be more likely to achieve long-term disease control after sHDRBT.

Outcomes and toxicities of re-irradiation for prostate cancer: A systematic review on behalf of the Re-Irradiation Working Group of the Italian Association of Radiotherapy and Clinical Oncology (AIRO)

AIMS

The best therapeutic approach for local relapses of previously irradiated prostate cancer (PC) is still not defined. Re-irradiation (Re-I) could offer a chance of cure for highly selected patients, although high quality evidences are lacking. The aim of our study is to provide a literature review on efficacy and safety of Re-I.

METHODS

Only studies where Re-I field overlaps with previous radiotherapy were considered. To determine 2 and 4 years overall mortality (OM), 2 and 4 years biochemical failure (BF) and pooled acute and late G ≥ 3 toxicities rate, a meta-analysis over single arm study was performed.

RESULTS

Thirty-eight studies with 1194 patients were included. Median follow-up from Re-I was 30 months (10-94 months). Brachytherapy (BRT) was the most used Re-I technique (27 studies), followed by Stereotactic Body Radiotherapy (SBRT) (9) and External Beam Radiation Therapy (EBRT) (2). Re-I prescription doses ranged from 19 Gy in single HDR fraction to 145 Gy (interstitial BRT). The pooled 2 and 4 years OM rates were 2.1% (95%CI:1.1-3.7%, P < 0.001) and 12.5% (95%CI:8.1-19.5%; P < 0.001). The pooled 2 years BF rate was 24% (95% CI: 19.1-30.2%, P < 0.001). The pooled 4 years BF was 35.6% (95% CI: 28.7-44.3%, P < 0.001). The pooled result of G ≥ 3 acute toxicity was 1.4% (95%CI: 0.7-3%, P < 0.001). One hundred and three G ≥ 3 late adverse events were reported, with a pooled result of G ≥ 3 late toxicity of 8.7% (95%CI: 5.8-13%, P < 0.001).

CONCLUSIONS

Re-I of local failures from PC showed promising OM and biochemical control rates with a safe toxicity profile.

Salvage reirradiation for local prostate cancer recurrence after radiation therapy. For who? When? How?

PURPOSE

Literature review reporting results of salvage brachytherapy and stereotactic body radiotherapy for prostate recurrence only after radiotherapy for prostate cancer.

MATERIALS AND METHODS

A total of 38 studies (including at least 15 patients per study) were analysed: 19 using low-dose-rate brachytherapy, nine high-dose-rate brachytherapy and ten stereotactic body radiotherapy. Only five studies were prospective. The median numbers of patients were 30 for low-dose-rate brachytherapy, 34 for high-dose-rate brachytherapy, and 30 for stereotactic body radiotherapy. The median follow-up were 47months for low-dose-rate brachytherapy, 36months for high-dose-rate brachytherapy and 21months for stereotactic body radiotherapy.

RESULTS

Late genitourinary toxicity rates ranged, for grade 2: from 4 to 42% for low-dose-rate brachytherapy, from 7 to 54% for high-dose-rate brachytherapy and from 3 to 20% for stereotactic body radiotherapy, and for grade 3 or above: from 0 to 24% for low-dose-rate brachytherapy, from 0 to 13% for high-dose-rate brachytherapy and from 0 to 3% for grade 3 or above (except 12% in one study) for stereotactic body radiotherapy. Late gastrointestinal toxicity rates ranged, for grade 2: from 0 to 6% for low-dose-rate brachytherapy, from 0 to 14% for high-dose-rate brachytherapy and from 0 to 11% for stereotactic body radiotherapy, and for grade 3 or above: from 0 to 6% for low-dose-rate brachytherapy, and from 0 to 1% for high-dose-rate brachytherapy and stereotactic body radiotherapy. The 5-year biochemical disease-free survival rates ranged from 20 to 77% for low-dose-rate brachytherapy and from 51 to 68% for high-dose-rate brachytherapy. The 2- and 3-year disease-free survival rates ranged from 40 to 82% for stereotactic body radiotherapy. Prognostic factors of biochemical recurrence have been identified.

CONCLUSION

Despite a lack of prospective data, salvage reirradiation for prostate cancer recurrence can be proposed to highly selected patients and tumours. Prospective comparative studies are needed.

Predictors for lower urinary tract symptoms and the urinary specific quality of life in prostate cancer patients: One-year follow-up

BACKGROUND

Prostate cancer (PCa) is the most frequently diagnosed cancer and is becoming a growing concern in global epidemiology. Quality of life of patients has become a major outcome for cancer care but limited study investigated quality of life of PCa patients. Our study is to investigate predictors for treatment outcomes of lower urinary tract symptoms (LUTS), nocturia, and the urinary specific quality of life (uQoL) in PCa patients one year following treatment.

METHODS

A prospective study of 131 consecutive patients was conducted with outcome measurements before treatment, at 3 months, 6 months, and one year following therapy. We utilized the International Prostate Symptom Score questionnaire to collect data. Generalized estimating equations were performed to identify predictors for major outcomes of LUTS, nocturia, and uQoL.

RESULTS

LUTS increased slightly over time, but nocturia and uQoL were improved from baseline to 12 months. Results of the interaction analysis indicated that patients with TNM stage 3 compared with those with stage 2 had a reduction in LUTS from diagnosis to 6 months. Patients who received surgery or radiation compared to hormone therapy had worse nocturia from diagnosis to 6 months compared to those of patients who received hormone therapy. Higher body mass index (BMI) decreased the uQoL from diagnosis to 3 months, and higher prostate-specific antigen (PSA) level deteriorated the uQoL from diagnosis to 12 months.

CONCLUSION

TNM stage and BMI affected the LUTS. Patients undergone a prostatectomy or radiation therapy showed more frequency of nocturia, BMI and PSA were also risk factors for nocturia. Moreover, patients' age, BMI, and PSA affected uQoL. In such patients, we recommend close monitoring of patients' specific characteristics such as TNM stage, BMI, and PSA for a better quality of life.

Salvage Therapy Options for Local Prostate Cancer Recurrence After Primary Radiotherapy: a Literature Review

PURPOSE OF REVIEW

While recurrence after primary treatment of prostate cancer (PCa) is not uncommon, there is currently no consensus on the most appropriate management after radiation treatment failure. This article seeks to explore the currently utilized modalities for salvage treatment for radiorecurrent PCa. We focused our review on the oncologic outcomes and reported toxicity rates in the latest studies examining salvage radical prostatectomy (SRP), salvage cryotherapy (SCT), salvage high-intensity focused ultrasound (HIFU) and re-irradiation.

RECENT FINDINGS

There does not appear to be any significant difference in overall survival for more invasive salvage radical prostatectomy compared to the minimally invasive salvage approaches. Additionally, there seems to be a trend towards lower morbidity rates associated with minimally invasive and focal salvage treatment. We are encouraged by the results presented in this review and find that there is clearly a role for emerging minimally invasive and focal therapies as durable options for salvage treatment in patients with radiorecurrent PCa.

Multiparametric MRI for the detection of local recurrence of prostate cancer in the setting of biochemical recurrence after low dose rate brachytherapy

PURPOSE

Prostate multiparametric magnetic resonance imaging (mpMRI) has utility in detecting post-radiotherapy local recurrence. We conducted a multireader study to evaluate the diagnostic performance of mpMRI for local recurrence after low dose rate (LDR) brachytherapy.

METHODS

A total of 19 patients with biochemical recurrence after LDR brachytherapy underwent 3T endorectal coil mpMRI with T2-weighted imaging, dynamic contrast-enhanced imaging (DCE) and diffusion-weighted imaging (DWI) with pathologic confirmation. Prospective reads by an experienced prostate radiologist were compared with reads from 4 radiologists of varying experience. Readers identified suspicious lesions and rated each MRI detection parameter. MRI-detected lesions were considered true-positive with ipsilateral pathologic confirmation. Inferences for sensitivity, specificity, positive predictive value (PPV), kappa, and index of specific agreement were made with the use of bootstrap resampling.

RESULTS

Pathologically confirmed recurrence was found in 15 of 19 patients. True positive recurrences identified by mpMRI were frequently located in the transition zone (46.7%) and seminal vesicles (30%). On patient-based analysis, average sensitivity of mpMRI was 88% (standard error [SE], 3.5%). For highly suspicious lesions, specificity of mpMRI was 75% (SE, 16.5%). On lesion-based analysis, the average PPV was 62% (SE, 6.7%) for all lesions and 78.7% (SE, 10.3%) for highly suspicious lesions. The average PPV for lesions invading the seminal vesicles was 88.8% (n=13). The average PPV was 66.6% (SE, 5.8%) for lesions identified with T2-weighted imaging, 64.9% (SE, 7.3%) for DCE, and 70% (SE, 7.3%) for DWI.

CONCLUSION

This series provides evidence that mpMRI after LDR brachytherapy is feasible with a high patient-based cancer detection rate. Radiologists of varying experience demonstrated moderate agreement in detecting recurrence.

Oncological outcome, complications, lower urinary tract symptoms, and health-related quality of life after low-dose-rate salvage brachytherapy for recurrent prostate cancer following primary radiotherapy: a report of 8 cases

Purpose

We evaluated our experience with low-dose-rate salvage brachytherapy for local recurrence after primary prostate radiotherapy, and described the changes in lower urinary tract symptoms and health-related quality of life.

Material and methods

Between 2011 and 2016, eight men with local recurrence after primary prostate radiotherapy underwent iodine-125 salvage brachytherapy with a prescribed dose of 110 or 145 Gy. Recurrence-free survival was evaluated with a post-treatment prostate-specific antigen profile. The toxicity and changes in lower urinary tract symptoms and health-related quality of life during the follow-up were evaluated on the Common Terminology Criteria for Adverse Events version 4.0, International Prostate Symptom Score, Short Form-8, and Expanded Prostate Cancer Index Composite, respectively.

Results

The median follow-up was 12.2 months (range, 8.3-71.9) after salvage brachytherapy. Of all eight patients, two (25%) experienced treatment failure, one of whom developed left seminal vesicle recurrence 36 months after salvage brachytherapy for the right seminal vesicle recurrence, while the other developed bone metastases after 6 months. The International Prostate Symptom Scores peaked at 3 months, and returned to baseline by 6 months. The scores of all domains of health-related quality of life remained unchanged during the 12-month follow-up after salvage brachytherapy. Early grade ≤ 2 genitourinary toxicity was observed in five patients (63%), and late grade 2 gastrointestinal toxicity in one patient (13%) having persistent diarrhea. No patient required intermittent catheterization and no grade 3 or greater toxicity occurred during follow-up.

Conclusions

The present study is our experiment of eight patients undergoing salvage brachytherapy, suggesting that this modality is noninvasive, safe, and an effective salvage local treatment in selected patients. To our knowledge, this is the first study to evaluate lower urinary tract symptoms and health-related quality of life in the post-treatment period in prostate cancer patients.

Evaluation of a Machine-Learning Algorithm for Treatment Planning in Prostate Low-Dose-Rate Brachytherapy

PURPOSE

This work presents the application of a machine learning (ML) algorithm to automatically generate high-quality, prostate low-dose-rate (LDR) brachytherapy treatment plans. The ML algorithm can mimic characteristics of preoperative treatment plans deemed clinically acceptable by brachytherapists. The planning efficiency, dosimetry, and quality (as assessed by experts) of preoperative plans generated with an ML planning approach was retrospectively evaluated in this study.

METHODS AND MATERIALS

Preimplantation and postimplantation treatment plans were extracted from 100 high-quality LDR treatments and stored within a training database. The ML training algorithm matches similar features from a new LDR case to those within the training database to rapidly obtain an initial seed distribution; plans were then further fine-tuned using stochastic optimization. Preimplantation treatment plans generated by the ML algorithm were compared with brachytherapist (BT) treatment plans in terms of planning time (Wilcoxon rank sum, α = 0.05) and dosimetry (1-way analysis of variance, α = 0.05). Qualitative preimplantation plan quality was evaluated by expert LDR radiation oncologists using a Likert scale questionnaire.

RESULTS

The average planning time for the ML approach was 0.84 ± 0.57 minutes, compared with 17.88 ± 8.76 minutes for the expert planner (P=.020). Preimplantation plans were dosimetrically equivalent to the BT plans; the average prostate V150% was 4% lower for ML plans (P=.002), although the difference was not clinically significant. Respondents ranked the ML-generated plans as equivalent to expert BT treatment plans in terms of target coverage, normal tissue avoidance, implant confidence, and the need for plan modifications. Respondents had difficulty differentiating between plans generated by a human or those generated by the ML algorithm.

CONCLUSIONS

Prostate LDR preimplantation treatment plans that have equivalent quality to plans created by brachytherapists can be rapidly generated using ML. The adoption of ML in the brachytherapy workflow is expected to improve LDR treatment plan uniformity while reducing planning time and resources.

Interstitial high-dose-rate brachytherapy as salvage treatment for locally recurrent prostate cancer after definitive radiation therapy: Toxicity and 5-year outcome

PURPOSE

We report our results with interstitial high-dose-rate brachytherapy (HDR-BT) as a salvage therapy option after external beam therapy with or without BT. Emphasis was put on toxicity and 5-year outcome.

METHODS AND MATERIALS

From 2003 to 2011, 29 patients with local failure after previous radiotherapy for prostate cancer were treated with salvage interstitial HDR-BT. The diagnosis of local recurrence was made on the basis of choline positron emission tomography. Salvage HDR-BT was given in three fractions with a single dose of 10 Gy per fraction and weekly. The target volume covered the peripheral zone of the prostate and the positron emission tomography-positive area. Acute and late toxicities were documented according to common terminology criteria for adverse events (CTCAE v 4.0).

RESULTS

Twenty-two patients with minimum followup of 60 months were analyzed. The 5-year overall survival was 95.5% with a disease-specific survival of 100%. The 5-year biochemical control was 45%. Late grade 2 gastrointestinal toxicities were observed in two patients (9%). No grade 3 or higher gastrointestinal late toxicities were observed. Urinary incontinence found in 2 patients (9%) and grade 2 obstruction of urinary tract occurred in one patient (4%).

CONCLUSIONS

Interstitial HDR-BT was feasible and effective in the treatment of locally recurrent prostate cancer after definitive radiotherapy. The long-term toxicity was low and acceptable.