Do androgen deprivation and the biologically equivalent dose matter in low-dose-rate brachytherapy for intermediate-risk prostate cancer?

Japanese clinical practice guidelines for prostate cancer 2023

This fourth edition of the Japanese Clinical Practice Guidelines for Prostate Cancer 2023 is compiled. It was revised under the leadership of the Japanese Urological Association, with members selected from multiple academic societies and related organizations (Japan Radiological Society, Japanese Society for Radiation Oncology, the Department of EBM and guidelines, Japan Council for Quality Health Care (Minds), Japanese Society of Pathology, and the patient group (NPO Prostate Cancer Patients Association)), in accordance with the Minds Manual for Guideline Development (2020 ver. 3.0). The most important feature of this revision is the adoption of systematic reviews (SRs) in determining recommendations for 14 clinical questions (CQs). Qualitative SRs for these questions were conducted, and the final recommendations were made based on the results through the votes of 24 members of the guideline development group. Five algorithms based on these results were also created. Contents not covered by the SRs, which are considered textbook material, have been described in the general statement. In the general statement, a literature search for 14 areas was conducted; then, based on the general statement and CQs of the Japanese Clinical Practice Guidelines for Prostate Cancer 2016, the findings revealed after the 2016 guidelines were mainly described. This article provides an overview of these guidelines.

Significance of androgen-deprivation therapy for intermediate- and high-risk prostate cancer treated with high-dose radiotherapy: A literature review

The real-world benefits of adding androgen-deprivation therapy (ADT) and its optimal duration when combined with current standard high-dose radiation therapy (RT) remain unknown. We aimed to assess the efficacy of and toxicities associated with ADT in the setting of combination with high-dose RT for intermediate-risk (IR) and high-risk (HR) prostate cancer (PCa). This article is a modified and detailed version of the commentary on Clinical Question 8 described in the Japanese Clinical Practice Guidelines for Prostate Cancer (ver. 2023). A qualitative systematic review was performed according to the Minds Guide. All relevant published studies between September 2010 and August 2020, which assessed the outcomes of IR or HR PCa treated with high-dose RT, were screened using two databases (PubMed and ICHUSHI). A total of 41 studies were included in this systematic review, mostly consisting of retrospective studies (N = 34). The evidence basically supports the benefit of adding ADT to high-dose RT to improve tumor control. Regarding IR populations, many studies suggested the existence of a subgroup for which adding ADT had no impact on either overall survival or the BF-free duration. On the other hand, regarding HR populations, several studies suggested the positive impact of adding ADT for ≥1 year on overall survival. Adding ADT increases not only the risk of sexual dysfunction but also that of cardiovascular toxicities or bone fracture. Although the benefit of adding ADT was basically suggested for both IR and HR populations, further investigations are warranted to identify subgroups of patients for whom ADT has no benefit, as well as the appropriate duration of ADT for those who do derive benefit.

Long-term outcomes of radical prostatectomy versus low-dose-rate brachytherapy in patients with intermediate-risk prostate cancer: Propensity score matched comparison

PURPOSE

To compare long-term outcomes of radical prostatectomy (RP) and low-dose-rate brachytherapy (LDR-BT) using propensity score-matched analysis in patients with clinically localized, intermediate-risk prostate cancer (PCa).

METHODS

Between October 2003 and March 2014, our institution treated 1241 patients with intermediate-risk PCa (RP: n = 531; LDR-BT: n = 710). Biochemical recurrence (BCR) was defined as prostate-specific antigen (PSA) levels of 0.2 ng/ml or greater for RP, and as PSA nadir plus 2 ng/ml or higher (Phoenix definition) for LDR-BT. We calculated propensity scores by multivariate logistic regression based on covariates that included age, pretreatment PSA, biopsy Gleason grade, the percentage of positive biopsy cores (PPBC), and clinical T stage.

RESULTS

Median follow-up was 108 months for RP and 99 months for LDR-BT. After propensity score adjustment, a total of 642 (321 each) patients remained for further analysis. Kaplan-Meier curves showed no statistically significant difference in overall survival (OS) (p = 0.99). LDR-BT was associated with improved BCR-free survival and salvage therapy-free survival  compared to RP (p < 0.001), and RP was associated with improved metastasis-free survival (MFS, p < 0.001).

CONCLUSION

BCR cannot be a surrogate for survival comparison, primarily due to differences between treatment modalities in how this term was defined post-therapy. Long-term follow-up showed that RP was associated with lower MFS in intermediate-risk PCa. However, this has not yet translated into superior OS.

Prognostic value of PSA bounce after definitive radiotherapy revisited

BACKGROUND

Prostate-specific antigen (PSA) bounce after definitive radiotherapy has been reported as a predictor of improved biochemical recurrence-free survival (BCRFS). We revisited this phenomenon to confirm its clinical impact on oncological outcomes in patients with long-term follow-up who were free of biochemical recurrence (BCR) at least 3 years after treatment.

MATERIALS AND METHODS

A total of 541 patients with localized, intermediate-risk prostate cancer underwent low-dose rate brachytherapy with iodine-125 seeds with or without supplemental external beam radiotherapy in combination. Neoadjuvant hormonal therapy was administered to 273 patients (50.5%) with a median duration of 3 months (range 1-108 months). PSA bounce was defined as ≥ 0.2 ng/ml increase above the interval PSA nadir, followed by a decrease below that value.

RESULTS

The median age was 69 years (range 49-90 years). The median follow-up duration was 102 months (range 36-205 months). One-hundred and fifty patients (27.7%) had PSA bounce with a median magnitude of 0.47 ng/ml (range 0.2-3.19 ng/ml). Age was significantly associated with the occurrence of PSA bounce [age: hazard ratio (HR) 0.95, 95% confidence interval (CI) 0.93-0.98]. It was found to be independently associated with a decreased risk for BCR (HR 0.29; 95% CI 0.12-0.69) and clinical progression (HR 0.44; 95% CI 0.95-0.98).

CONCLUSION

PSA bounce indicated a favorable BCRFS and clinical progression-free survival in patients who had been free of BCR for at least 3 years after definitive radiotherapy.

How long is long enough to secure disease control after low-dose-rate brachytherapy in combination with other modalities in intermediate-risk, localized prostate cancer?

PURPOSE

Previous studies have demonstrated excellent overall outcomes in patients who underwent low-dose-rate brachytherapy (LDR-BT) in intermediate-risk, localized prostate cancer (PCa). We thus investigated the appropriate length of time before completing prostate-specific antigen (PSA) monitoring after treatment.

PATIENTS AND METHODS

Between 2003 and 2014, 710 localized, intermediate-risk PCa patients underwent LDR-BT with or without supplemental external beam radiotherapy (EBRT). Data from 567 of those patients was analyzed in this study. Neoadjuvant hormonal therapy (NHT) was administered to 315 patients (55.6 %) and NHT with adjuvant hormonal therapy (AHT) to 59 patients (10.4 %), as per the protocol of a prospective randomized controlled trial (SHIP0804). We stratified patients by posttreatment PSA levels at specific times and assessed the factors for association with biochemical recurrence (BCR) and for clinical progression (CP).

RESULTS

The median follow-up was 109 months (range, 60-205 months). Of 529 patients who were BCR-free at 3 years after treatment, 56 subsequently developed BCR, and 47 developed CP. PSA at 3 and 5 years after treatment were significantly correlated with long-term oncological outcomes. No patients with 5-year PSA levels ≤0.1 ng/mL subsequently developed BCR or CP.

CONCLUSION

Discontinuation of PSA monitoring could be discussed with patients with intermediate-risk PCa as a reasonable option if PSA levels remain ≤0.1 ng/mL at 5 years after LDR-BT, either alone or with other combined modalities, as subsequent recurrences are quite rare.

Do androgen deprivation and the biologically equivalent dose matter in low-dose-rate brachytherapy for intermediate-risk prostate cancer?

The objective of this study was to investigate the impact of the biologically equivalent dose (BED) on treatment outcomes after iodine‐125 low‐dose‐rate brachytherapy (LDR‐BT) with or without supplemental external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT) for intermediate‐risk prostate cancer (PCa). We retrospectively evaluated 292 Japanese patients. The impact of the BED and ADT on treatment outcomes was investigated. Cox proportional hazard models were used for univariate and multivariate analysis with biological progression‐free survival (bPFS) and clinical progression‐free survival (cPFS) as the primary outcome measures. The median follow‐up was 66 months. The bPFS and cPFS rates at 5‐/7‐years were 91.6/87.7% and 95.9/94.0%, respectively. When stratified by BED levels, the bPFS rates at 5‐/7‐years were 92.1/89.3% for <178.0 Gy_2, and 91.2/86.0% for ≥178.0 Gy₂, respectively (P > 0.05). Based on ADT duration, the bPFS rates at 5‐/7‐years were 89.8/83.5%, 89.7/89.7%, and 97.5/97.5% for none, 1–3 months, and 4–12 months, respectively (P = 0.03). For the univariate analysis, the use of ADT and its duration were significant predictors for bPFS, whereas BED was not significant. A multivariate analysis did not indicate the use of ADT itself was significant, however, when covariates were accounted for by the duration of ADT, the longer use of ADT was found to significantly improve bPFS. Although cPFS was associated neither with the BED levels nor ADT duration (P > 0.05), ADT duration had a trend of improving cPFS (P = 0.053). The higher levels of BED did not significantly impact bPFS for intermediate‐risk PCa after LDR‐BT with or without supplemental EBRT and ADT. The longer duration of ADT could provide an additional benefit in the context of high‐dose irradiation generated by LDR‐BT.