Comparing Adjuvant and Early Salvage Radiotherapy for Prostate Cancer After Surgery
Posted: Thursday, October 17, 2019
A new phase III trial was unable to rule out the possibility that observation with early salvage radiotherapy is 10% worse than adjuvant radiotherapy at reducing the risk of biochemical failure after radical prostatectomy. In other words, early salvage radiotherapy may be inferior, although it may not. The rates of freedom from biochemical failure in the two trial arms were similar. The research was presented at the 2019 American Society for Radiation Oncology (ASTRO) Annual Meeting (Abstract 77) by Andrew Kneebone, MD, MBBS, of the Royal North Shore Hospital, and colleagues and published in the International Journal of Radiation Oncology • Biology • Physics.
“Salvage radiotherapy spares approximately half of men from pelvic radiotherapy and is associated with significantly lower levels of genitourinary toxicity,” the authors wrote.
The TROG 08.03 and ANZUP “RAVES” trial included 333 patients with high-risk prostate cancer at 32 institutions in Australia and New Zealand. All patients had extraprostatic extension, seminal vesicle invasion, or positive surgical margins, as well as postoperative prostate-specific antigen (PSA) levels of up to 0.10 ng/mL. Patients were randomly assigned to receive either adjuvant radiotherapy beginning within 6 months of prostatectomy or “close observation with early salvage radiotherapy triggered by a PSA level of 0.20 ng/mL or greater.” The authors defined biochemical failure as a PSA level of at least 0.40 ng/mL or beginning androgen deprivation after radiotherapy.
The median follow-up for the intent-to-treat analysis was 6.1 years. After 8 years, the rates of freedom from biochemical failure were 79% with adjuvant radiotherapy and 76% with salvage radiotherapy. At 8 years, the rates of local, regional, or distant failure were 6% with adjuvant radiotherapy and 5% with salvage radiotherapy.
Half of the patients in the salvage-radiotherapy arm never needed radiotherapy, and the other 50% experienced a PSA rise to at least 0.2 ng/mL, triggering salvage radiotherapy. The salvage-radiotherapy arm had significantly lower rates of grade 2+ genitourinary toxicity than the adjuvant-radiotherapy arm. The grade 2+ gastrointestinal toxicity rates were similar in the two arms.
Disclosure: The study authors reported no conflicts of interest.