CHICAGO—Adding short-term hormonotherapy to salvage radiotherapy significantly improved 10-year metastasis-free survival compared with salvage radiotherapy alone, according to the results of GETUG-AFU 16 (abstract 5001) presented at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting, held May 31–June 4 in Chicago.
After radical prostatectomy, radiotherapy is the standard salvage treatment. GETUG-16 is a phase III clinical trial that sought to define the utility of hormonotherapy plus radiotherapy in the treatment of prostate cancer. The investigators assessed the efficacy of radiotherapy alone vs radiotherapy plus hormonotherapy in patients with biological relapse after radiotherapy. The primary endpoints were progression-free survival (PFS), metastasis-free survival (MFS), and overall survival (OS). The results were an update from the initial 5-year follow-up, which revealed that patients who received radiotherapy plus hormonotherapy had a higher PFS rate (80%) compared with those who received radiotherapy alone (62%; P < .0001).
“In terms of PFS, we had a hazard ratio of 0.545, and nowadays we have approximately a 10-year median follow-up, we [can] confirm what we observed 4 years ago,” said Christian Carrie, MD, of the department of radiation oncology at Centre Léon Bérard in Lyon, France, who presented the results during the meeting.
In total, 743 patients (median age, 67 years) were randomized to receive radiotherapy alone (n = 374) or radiotherapy plus hormonotherapy (goserelin) for 6 months (n = 369). Patients were stratified according to radiotherapy modality and risk group.
The median follow-up duration was 112 months, or 9.3 years. As before, the patients who received radiotherapy plus hormonotherapy had improved PFS (hazard ratio [HR], 0.54; 95% CI, 0.43–0.68; P< .0001), and the improvement was irrespective of the risk subgroup (low risk: HR, 0.47; 95% CI, 0.28–0.80 and high risk: HR, 0.56; 95% CI, 0.44–0.73). MFS was also improved for patients who received radiotherapy plus hormonotherapy (HR, 0.73; 95% CI, 0.54–0.98; P = .034). The MFS rate for patients who received radiotherapy plus hormonotherapy was 75% (95% CI, 70%–80%) compared with 69% (95% CI, 63%–74%) for those who received radiotherapy alone.
Dr Carrie explained that as with the earlier 5-year follow-up, there was no increase in toxicity or changes in quality of life by adding hormonotherapy to the radiation therapy. At the 5-year follow-up, the most common adverse events of grade 3 or worse were genitourinary events (8% in the radiotherapy-alone group vs 7% in the radiotherapy plus goserelin group) and sexual disorders (5% vs 8%, respectively).
“We know there are side effects of short-term hormonal therapy, but they largely recover,” said Daniel Spratt, MD, of the University of Michigan, who was the discussant for the study. “And now, with longer follow-up, could there be quality-of-life improvements from that year of delayed MFS? Probably for some patients. Could there be quality-of-life benefits? Probably, also, for some patients. And who are those patients?”
Spratt went on to suggest that to be able to personalize this treatment, the GETUG team should next report MFS outcome by prostate-specific antigen (PSA) level because presalvage PSA levels have been shown to be a predictive biomarker of hormonotherapy benefit.
The authors suggest that radiotherapy plus hormonotherapy should be considered the new standard for salvage treatment after radical prostatectomy.
“The improvement in MPS could allow postponement of more aggressive treatment, such as long-term androgen suppression with deleterious effect on quality of life,” concluded Carrie.