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Prostate cancer: Adjuvant radiotherapy fails in phase 3 trial

Publish date:: November 24, 2020

Key clinical point: In patients with prostate cancer undergoing radical prostatectomy (RP), adjuvant radiotherapy was comparable to salvage radiotherapy in PSA biochemical progression, but had worse urinary and bowel morbidity.

Major finding: At 5 years, biochemical progression-free survival rate was 85% in the adjuvant radiotherapy group and 88% in the salvage radiotherapy group (hazard ratio, 1.10; P = .56). The adjuvant vs salvage radiotherapy group reported worse urinary incontinence (P = .0023) and fecal incontinence (P less than .0001).

Study details: In the phase 3, randomized RADICALS-RT study included 1396 patients with nonmetastatic prostate cancer who underwent RP were randomly assigned to salvage radiotherapy or adjuvant radiotherapy.

Disclosures: The study was funded by Cancer Research UK, MRC Clinical Trials Unit, and Canadian Cancer Society. CC Parker, NW Clarke, C Catton, H Payne, F Saad, H Lindberg, A Zarkar, MKB Parmar, and MR Sydes reported ties with various pharmaceutical companies. The remaining authors declared no conflicts of interest.

Commentary

“Previous randomized controlled trials of adjuvant radiation after prostatectomy have demonstrated some benefit with regard to a reduction in early biochemical recurrence; however, conflicting results with respect to long-term outcomes have been observed. In the RADICALS-RT study, patients with localized prostate cancer and at least one risk factor for biochemical progression after prostatectomy were randomized to adjuvant radiation or a salvage radiation approach. There was no improvement in biochemical progression-free survival or freedom from non-protocol hormone therapy in the treatment group, while the treatment group experienced more urinary incontinence. The study has not matured enough for a report on the primary outcome, freedom from distant metastases. The interim findings do not support utilization of adjuvant radiation over a salvage radiation approach. In addition, adjuvant radiation may result in more urinary incontinence compared with a salvage radiation approach.”