Adjuvant Radiotherapy Benefits Some
Recent randomized trials have shown that following radical prostatectomy for prostate cancer, adjuvant radiotherapy improves progression-free survival (PFS). Nevertheless, it is possible that some patients with adverse pathological features may be appropriate candidates for delayed salvage radiotherapy.
To further explore this issue, a team led by William Catalona, MD, of the Northwestern Feinberg School of Medicine in Chicago, studied more than 3,400 men who underwent radical prostatectomy. From this population, they isolated men with aggressive pathology in the surgical specimen, of whom 198 received adjuvant radiation and 724 were observed.
Of the observed patients, 120 ultimately received salvage radiation therapy. Patients were classified into risk groups for the analysis. Low risk was defined as a PSA level of 10 ng/mL or less, a Gleason score less than 7, and clinical stage T1 or T2a. Intermediate risk was defined as a PSA level 10.1-20 ng/mL, a Gleason score of 7, or clinical stage T2b/c. High risk was defined as a PSA level greater than 20 ng/mL, a Gleason score higher than 7, or clinical stage T3a.First, the investigators calculated that the seven-year progression-free survival (PFS) for adjuvant radiotherapy was at least 70% for low-risk patients with positive surgical margins (SM+), extracapsular extension (ECE), or seminal vesicle invasion (SVI). Seven-year PFS for intermediate-risk patients ranged from 52% to 73%. Among high-risk patients, the seven-year PFS was 39% and 24% for those with SM+/ECE and those with SVI, respectively.
The group of men who went on to receive salvage radiotherapy had a median follow-up of 60 months, and the results were also favorable. For example, in the men who were initially observed and ultimately treated with salvage therapy, only three men developed metastatic disease. All three were clinically high-risk and had seminal vesicle invasion in the radical prostatectomy specimen.
“Overall,” Dr. Catalona noted, “there was a low risk of progression in low-risk patients whether or not adjuvant therapy was given. However, men who are clinically high risk or had seminal vesicle invasion had less favorable results despite adjuvant therapy. These considerations must be weighed against the additional side effects of radiation therapy, and further randomized studies are needed to determine the optimal strategy for men with high-risk features. It is possible that delayed salvage radiation may be the best approach for low-risk and some intermediate-risk patients.”