Radical Prostatectomy, External Beam Radiotherapy, or External Beam Radiotherapy With Brachytherapy Boost and Disease Progression and Mortality in Patients With Gleason Score 9-10 Prostate Cancer

Abstract

Importance: The optimal treatment for Gleason score 9-10 prostate cancer is unknown.

Objective: To compare clinical outcomes of patients with Gleason score 9-10 prostate cancer after definitive treatment.

Design, setting, and participants: Retrospective cohort study in 12 tertiary centers (11 in the United States, 1 in Norway), with 1809 patients treated between 2000 and 2013.

Exposures: Radical prostatectomy (RP), external beam radiotherapy (EBRT) with androgen deprivation therapy, or EBRT plus brachytherapy boost (EBRT+BT) with androgen deprivation therapy.

Main outcomes and measures: The primary outcome was prostate cancer-specific mortality; distant metastasis-free survival and overall survival were secondary outcomes.

Results: Of 1809 men, 639 underwent RP, 734 EBRT, and 436 EBRT+BT. Median ages were 61, 67.7, and 67.5 years; median follow-up was 4.2, 5.1, and 6.3 years, respectively. By 10 years, 91 RP, 186 EBRT, and 90 EBRT+BT patients had died. Adjusted 5-year prostate cancer-specific mortality rates were RP, 12% (95% CI, 8%-17%); EBRT, 13% (95% CI, 8%-19%); and EBRT+BT, 3% (95% CI, 1%-5%). EBRT+BT was associated with significantly lower prostate cancer-specific mortality than either RP or EBRT (cause-specific HRs of 0.38 [95% CI, 0.21-0.68] and 0.41 [95% CI, 0.24-0.71]). Adjusted 5-year incidence rates of distant metastasis were RP, 24% (95% CI, 19%-30%); EBRT, 24% (95% CI, 20%-28%); and EBRT+BT, 8% (95% CI, 5%-11%). EBRT+BT was associated with a significantly lower rate of distant metastasis (propensity-score-adjusted cause-specific HRs of 0.27 [95% CI, 0.17-0.43] for RP and 0.30 [95% CI, 0.19-0.47] for EBRT). Adjusted 7.5-year all-cause mortality rates were RP, 17% (95% CI, 11%-23%); EBRT, 18% (95% CI, 14%-24%); and EBRT+BT, 10% (95% CI, 7%-13%). Within the first 7.5 years of follow-up, EBRT+BT was associated with significantly lower all-cause mortality (cause-specific HRs of 0.66 [95% CI, 0.46-0.96] for RP and 0.61 [95% CI, 0.45-0.84] for EBRT). After the first 7.5 years, the corresponding HRs were 1.16 (95% CI, 0.70-1.92) and 0.87 (95% CI, 0.57-1.32). No significant differences in prostate cancer-specific mortality, distant metastasis, or all-cause mortality (≤7.5 and >7.5 years) were found between men treated with EBRT or RP (cause-specific HRs of 0.92 [95% CI, 0.67-1.26], 0.90 [95% CI, 0.70-1.14], 1.07 [95% CI, 0.80-1.44], and 1.34 [95% CI, 0.85-2.11]).

Conclusions and relevance: Among patients with Gleason score 9-10 prostate cancer, treatment with EBRT+BT with androgen deprivation therapy was associated with significantly better prostate cancer-specific mortality and longer time to distant metastasis compared with EBRT with androgen deprivation therapy or with RP.

Figure.. Adjusted Survival Curves for Prostate Cancer–Specific Survival, Distant Metastasis–Free Survival, and Overall Survival by Treatment Group, Weighted by the Inverse Probability of Treatment

EBRT indicates external beam radiotherapy; and EBRT+BT, external beam radiotherapy with a brachytherapy boost. Median follow-up for each treatment cohort was as follows: EBRT, 5.1 years (interquartile range, 2.9-7.7 years); EBRT+BT, 6.3 years (interquartile range, 3.9-9.4 years); and surgery, 4.2 years (interquartile range, 2.5-7.0 years). Adjusted curves were generated with Kaplan-Meier methods with inverse probability of treatment weights, calculated with propensity scores that were determined by using multinomial logistic regression with treatment cohort as the outcome and age, ln(initial prostate-specific antigen level), clinical T stage, and Gleason score as pretreatment, prognostic covariates. Numbers at baseline differ for A from both B and C because not all patients had known cause-of-death information to compute prostate cancer–specific survival.