Adjuvant radiotherapy following radical prostatectomy (RP) for prostate cancer (PCa) is associated with better biochemical recurrence-free survival than RP alone among patients who have positive surgical margins or extracapsular extension, according to a new Finnish study.
The study enrolled 250 patients with pT2 prostate tumors and positive surgical margins or pT3aN0M0 cancer without seminal vesicle invasion. Investigators randomly assigned 126 patients to receive adjuvant radiotherapy (5 of whom declined post-RP radiotherapy following randomization to this study arm) and 124 to receive RP alone (observation arm). The radiation dose in the adjuvant group was 66.6 Gy given in 37 fractions.
The median follow-up time for patients who were alive at the end of follow-up was 9.3 years in the adjuvant group compared with 8.6 years in the observation arm.
The 10-year biochemical recurrence-free survival rate was 82% in the adjuvant group compared with 61% in the RP-only arm, Greetta Hackman, MD, of the University of Helsinki, and collaborators reported in European Urology. The adjuvant group had a significant 74% decreased risk of biochemical recurrence compared with the observation arm. The 10-year overall survival rates did not differ significantly between the adjuvant and observation groups (92% and 87%, respectively). Only 2 patients died from PCa, 1 in each group. The 10-year PCa-specific survival rate was 99% in both groups.
Of the 124 patients in the RP-only arm, 37 received salvage radiotherapy for protocol-defined progression, after which 28 remained recurrence free.
In the adjuvant radiotherapy group, 56% of patients experienced grade 3 adverse events compared with 40% in the observation arm.
“In summary, adjuvant radiotherapy prolongs the time from radical prostatectomy to biochemical recurrence with the strongest impact on pT2 disease with positive margins and Gleason score 5-7, the authors concluded. “However, adjuvant radiotherapy causes more adverse effects compared with observation, and salvage therapy upon biochemical recurrence appears as effective as adjuvant therapy with regard to overall survival.”
The investigators also stated: “Only the patient can balance the subjective questions of radiation-related adverse events to a lower risk of biochemical recurrence, cancer progression, and its consequences.”
Hackman G, Taari K, Tammela TL, et al. Randomised trial of adjuvant radiotherapy following radical prostatectomy versus radical prostatectomy alone in prostate cancer patients with positive margins or extracapsular extension. Eur Urol. 2019.