Impact of Biochemical Failure After Salvage Radiation Therapy on Prostate Cancer–specific Mortality: Competition Between Age and Time to Biochemical Failure

External validation of biochemical recurrence definition to predict oncologic outcomes following focal therapy for localized prostate cancer using high intensity focused ultrasound

PURPOSE

This is an external validation of several biochemical recurrence definitions based on prostate specific antigen criteria (PSA). The purpose is to predict the need of additional treatment and failure after focal therapy using high intensity focused ultrasound (HIFU) for localized prostate cancer (PCa).

MATERIALS AND METHODS

A total of 343 consecutive patients who underwent HIFU with Ablatherm® and Focal One® devices between June 2001 and November 2020 were identified. Treatment failure was defined as clinically significant PCa on postoperative biopsy, the need for salvage radical or systematic treatment, metastasis, or PCa-related death. The biochemical recurrence definitions tested were PSA nadir, time to PSA nadir, percentage of PSA reduction, Huber et al. criteria defined as PSA nadir + 1 ng/mL at 12 months or PSA nadir + 1.5 ng/mL at 24-36 months. Multivariable Cox regression analysis and decision-curve analysis were used to validate and compare criteria. Kaplan-Meier analysis was used to assess criteria associated with the highest accuracy.

RESULTS

One hundred seventy-eight patients met the inclusion criteria and were analyzed. Overall, 61 (34%) and 41 (23%) patients had an additional treatment and failure with a median follow-up of 52 months. At multivariable analysis, model including Huber et al. criteria exhibited the highest Harrell's C-index for the prediction of the need of additional treatment (hazard ratio [HR]: 10, p < 0.001, c-index: 84%) and treatment failure (HR: 9.1, p < 0.001, c-index: 82%) as well as higher net benefit. The 60-months need of additional treatment and treatment failure-free survival were 89% and 98% compared to 26% and 49%, respectively, when stratified according to Huber et al. criteria (Log-rank test, p < 0.001). Similar results were found after excluding patient with non-clinically significant PCa at initial biopsy.

CONCLUSIONS

We report an external validation of biochemical recurrence definitions predicting the need of additional treatment and failure after focal therapy using HIFU for localized PCa. Huber et al. criteria were identified as the most accurate and could be used to guide clinicians toward further evaluation and salvage treatments.

Failure Patterns by PSMA PET for Recurrent Prostate Cancer after Prostatectomy and Salvage Radiation

OBJECTIVE

To characterize patterns of failure using prostate-specific membrane antigen positron emission tomography (PSMA PET) after radical prostatectomy (RP) and salvage radiotherapy (SRT).

METHODS

Patients with rising PSA post-RP+SRT underwent 68Ga-HBED-iPSMA PET/CT on a single-arm, prospective imaging trial (NCT03204123). Scans were centrally reviewed with pattern-of-failure analysis by involved site. Positive scans were classified using 3 failure categories: pelvic nodal, extra-pelvic nodal or distant non-nodal. Associations with failure categories were analyzed using cumulative incidence and generalized logits regression.

RESULTS

We included 133 men who received SRT a median of 20 months post-RP; 56% received SRT to the prostatic fossa alone, while 44% received pelvic SRT. PSMA PET/CT was performed a median of 48 months post-SRT. Overall, 31% of PSMA PET/CT scans were negative, 2% equivocal and 67% had at least 1 positive site. Scan detection was significantly associated with PSA level prior to PSMA PET/CT. Analysis of 89 positive scans demonstrated pelvic nodal (53%) was the most common relapse and fossa relapse was low (9%). Overall, positive scans were pelvic (n = 35, 26%), extra-pelvic nodal (n = 26, 20%) or distant non-nodal failure (n = 28, 21%), and 70% of positive scans were oligorecurrent. We observed similar cumulative incidence for all failure categories and relatively few clinicodemographic associations. Men treated with pelvic SRT had reduced odds of pelvic failure versus exclusive fossa treatment.

CONCLUSION

Pelvic, extra-pelvic nodal, and distant non-nodal failures occur with similar incidence post-SRT. Regional nodal relapse is relatively common, especially with fossa-only SRT. A high oligorecurrence rate suggests a potentially important role for PSMA-guided focal therapies.

Pathological stage, surgical margin and lymphovascular invasion as prognostic factors after salvage radiotherapy for post-prostatectomy relapsed prostate cancer - outcomes and optimization strategies

Background

Salvage radiotherapy (sRT) is the main potentially curative treatment after biochemical failure/locoregional relapse post-radical prostatectomy (RP). The aim of the study was to characterize the population who underwent sRT after RP at our Department, to understand the influence of several potential prognosis factors, and to determine possible optimization strategies.

Materials and methods

We retrospectively analyzed patients undergoing sRT at our department between 2012 and 2017, evaluating patient, tumor and treatment characteristics, restaging procedures and clinical outcomes - namely biochemical relapse-free survival (BC-RFS), clinical relapse-free survival (C-RFS), additional hormone therapy-free survival (HT-FS) and overall survival (OS). We assessed potential prognostic factors by univariate and multivariate models (MVA).

Results

We included 277 patients (median age 68 years). Median pre-sRT PSA was > 0.5ng/mL in 54.9%. All underwent prostate bed irradiation. Pelvic lymph nodes were included in 9.7%. Outcome analysis was performed for 264 patients (35.6 months median follow-up). At 3 years, BC-RFS was 61.4%, C-RFS was 81.3%, HT-FS was 79.9% and OS was 96.6%. Most relapses occurred in regional lymph nodes only (47.9% patients who relapsed). On MVA, lymphovascular invasion, advanced pT-stages and negative margins negatively influenced BC-RFS (p = 0.029, p = 0.002 and p < 0.001) and HT-FS (p = 0.001, p = 0.029 and p = 0.002). C-RFS was worsened by lymphovascular invasion (p = 0.009) and negative margins (p = 0.015). These had no effect on OS. BC-RFS and HT-FS were improved when sRT started while PSA ≤ 0.5 ng/mL (p < 0.05).

Conclusion

Lymphovascular invasion, higher pT-stages and negative margins negatively affected prognosis. An early start of sRT (PSA ≤ 0.5 ng/mL) predicted better BC-RFS and HT-FS.

Impact of Decipher on use of post‐operative radiotherapy: Individual patient analysis of two prospective registries

Objective

To assess the association between Genomic Classifier (GC)‐risk group and post‐radical prostatectomy treatment in clinical practice.

Methods

Two prospective observational cohorts of men with prostate cancer (PCa) who underwent RP in two referral centers and had GC testing post‐prostatectomy between 2013 and 2018 were included. The primary endpoint of the study was to assess the association between GC‐risk group and time to secondary therapy. Univariable (UVA) and multivariable (MVA) Cox proportional hazards models were constructed to assess the association between GC‐risk group and time to receipt of secondary therapy after RP, where secondary therapy is defined as receiving either RT or ADT after RP.

Results

A total of 398 patients are included in the analysis. Patients with high‐GC risk were more likely to receive any secondary therapy (OR: 6.84) compared to patients with low/intermediate‐GC risk. The proportion of high‐GC risk patients receiving RT at 2 years post‐RP was 31.5%, compared to only 6.3% among the low/intermediate‐GC risk patients.

Conclusion

This study demonstrates that physicians in routine practice used GC to identify high risk patients who might benefit the most from secondary treatment. As such, GC score was independent predictor of receipt of secondary treatment.