Conditional biochemical recurrence-free survival after radical prostatectomy in patients with high-risk prostate cancer

Conditional Risks of Biochemical Failure and Prostate Cancer-Specific Death in Patients Undergoing External Beam Radiotherapy: A Secondary Analysis of 2 Randomized Clinical Trials

Importance

As patients achieve years of survival after treatment for prostate cancer, the risk of biochemical failure (BF) or prostate cancer-specific death (PCSD) may evolve over time, with clinical relevance to both patients and clinicians.

Objective

To determine conditional BF-free survival, PSCD, and overall survival estimates for patients with low- or intermediate-risk prostate cancer enrolled in the Radiation Therapy Oncology Group (RTOG) 0126 and RTOG 0415 clinical trials. A secondary objective was to determine whether prognostic factors at diagnosis remain relevant at later points in follow-up.

Design, Setting, and Participants

A pooled secondary analysis of patients treated with external-beam radiotherapy alone and enrolled in the prospective randomized clinical trials RTOG 0126 and RTOG 0415 was performed. Patients included for analysis were enrolled between March 2002 and December 2009 with a median follow-up of 6.9 years. Overall survival was calculated using the Kaplan-Meier method at various survivorship time points. Cumulative incidence was used to calculate BF rates using the Phoenix definition, as well as PCSD. Risk factors such as Gleason score, tumor (T) stage, prostate-specific antigen level, and the equivalent dose in 2 Gy fractions of prescribed dose were analyzed at different time points using multivariable Cox proportional hazards modeling. Data were analyzed from November 2021 to February 2023.

Main Outcomes and Measures

Conditional risks of BF and PCSD after completion of external-beam radiotherapy.

Results

A total of 2591 patients (median [IQR] age, 69 [63-73] years) were included in the study with a mean (range) PSA level of 7.1 (4.7-8.9) ng/mL, 1334 patients (51.5%) with a Gleason score 6 disease, and 1706 patients (65.8%) with T1 disease. Rates of BF from time of treatment were 1.63% (95% CI, 1.20%-2.18%) at 1 year, 7.04% (95% CI, 6.09%-8.08%) at 3 years, 12.54% (95% CI, 11.28%-13.88%) at 5 years, and 22.32% (95% CI, 20.46%-24.24%) at 8 years. For patients surviving 1, 3, and 5 years without BF, the rates of BF in the next 5 years were 14.20% (95% CI, 12.80%-15.66%), 17.19% (95% CI, 15.34%-19.14%), and 18.85% (95% CI, 16.21%-21.64%), respectively. At the initial time point, the rate of PCSD in the next 5 years was 0.66% (95% CI, 0.39%-1.04%). For patients who achieved 1, 3, 5, and 8 years of survivorship, the rates of PCSD in the next 5 years were 1.16% (95% CI, 0.77-1.67) at 1 year, 2.42% (95% CI, 1.74%-3.27%) at 3 years, 2.88% (95% CI, 2.01%-3.99%) at 5 years, and 3.49% (95% CI, 0.98%-8.73%) at 8 years.

Conclusions and Relevance

In this secondary analysis of 2 randomized clinical trials of patients undergoing external beam radiotherapy for prostate cancer, the conditional risks of BF and death from prostate cancer increased with time for patients with low- and intermediate-risk prostate cancer treated with radiotherapy alone. These results could inform optimal trial design and may be helpful information for patients evaluated in follow-up.

Trial Registration

ClinicalTrials.gov Identifier: NCT00033631; NCT00331773.

Novel nomogram to predict biochemical recurrence-free survival after radical prostatectomy

PURPOSE

Conditional survival represents the probability of subsequent survival given that patients have already survived a certain length of time. Several models predict biochemical recurrence (BCR) after radical prostatectomy. However, none of them include postoperative prostate-specific antigen (PSA). We aimed to analyze BCR-free survival evolution over time and develop a nomogram incorporating the postoperative PSA value to predict BCR-free survival.

MATERIAL AND METHODS

We included patients treated with robot-assisted radical prostatectomy (RARP) for prostate cancer between 2009 and 2021 and calculated conditional survival. Cox proportional hazard regression analysis was used to assess the predictive variables of BCR. We developed a nomogram predicting BCR-free survival three and five years after RARP. We used c-index and decision curve analyses to compare the nomogram with the Cancer of the Prostate Risk Assessment post-Surgical (CAPRA-S) score.

RESULTS

We included 718 patients. The overall 3- and 5-year BCR-free survival rates were 85.1% and 75.7%, respectively. The 5-year BCR-free survival rates increased to 78.9%, 82.9%, 85.2%, and 84.7% for patients surviving 1, 2, 3, and 4 years without BCR, respectively. We developed a nomogram including the pathological Gleason score and T stage, positive surgical margin, PSA ≥ 0.05 ng/mL at one year, and lymph node involvement to predict BCR at 3 and 5 years postoperatively. Our nomogram presented a higher c-index (0.89) than the CAPRA-S score (0.78; p = 0.001) and a positive net benefit at 3 and 5 years postoperatively in the decision curve analyses.

CONCLUSION

The 5-year conditional BCR-free survival increased with survival without BCR. The developed nomogram significantly improved the accuracy in predicting BCR-free survival after RARP.

Prognostic factors in postoperative radiotherapy for prostate cancer - tertiary center experience

BACKGROUND

The aim of the study was to analyse the prognostic factors in postoperative prostate cancer irradiation and develop a nomogram for disease-free survival (DFS).

PATIENTS AND METHODS

This retrospective study included 236 consecutive prostate cancer patients who had radical prostatectomy followed by radiotherapy (RT) at a single tertiary institution between 2009 and 2014. The main outcome was DFS analysed through uni- and multivariable analysis, Kaplan-Meier curves, log-rank testing, recursive partitioning analysis, and nomogram development.

RESULTS

The median follow up was 62.3 (interquartile range [IQR] 38.1-79) months. The independent clinical factors associated with increased risk of recurrence or progression in the multivariate analysis (MVA) were prostate-specific antigen (PSA) level before RT, pT3 characteristic, and local failure as salvage indication. The value of PSA nadir had a significant impact on the risk of biochemical failure. Biochemical control and DFS were significantly different depending on treatment indication (p < 0.0001). The recursive partitioning analysis highlighted the importance of the PSA level before RT, Gleason Grade Group, PSA nadir, and local failure as a treatment indication. Finally, the nomogram for DFS was developed and is available online at https://apps.konsta.com.pl/app/prostate-salvage-dfs/.

CONCLUSIONS

The Pre-RT PSA level, pT3 characteristic and local failure as salvage indication are pivotal prognostic factors associated with increased risk of recurrence or progression. The Gleason grade group of 4-5 and PSA nadir value allow for further risk stratification. The treatment outcomes in postoperative prostate cancer irradiation are significantly different depending on treatment indication. An online nomogram comprising of both pre-treatment and current data was developed allowing for visualization of changes in prognosis depending on clinical data.