Dr. Resnick and colleagues are to be congratulated for following men on the PCOS study out to 15 years. The main result—“At 15 years, no significant relative differences in disease-specific functional outcomes were observed among men undergoing prostatectomy or radiotherapy”—should be interpreted with the following two caveats in mind.
First, there is a numerical trend for increased urinary incontinence at 15 years in men undergoing surgery (18.3%) as compared to radiation (9.4%) and, similarly, a numerical trend for increased bowel dysfunction in the radiation (35.8%) as compared to the surgical (21.9%) group. These trends may have been statistically significant if all men evaluable at 5 years were still alive at 15 years. Specifically, the authors state that “at the time of the 15-year survey, 322 of the 1,164 men in the prostatectomy group (27.7%) and 247 of the 491 men in the radiotherapy group (50.3%) had died.” Therefore, the power to achieve statistical significance in the numerical trends observed at 15 years is limited by intercurrent deaths.
Second, the authors state at the end of the discussion that “Although we evaluated the comparative harms of prostatectomy and radiotherapy, the precise contribution of prostate cancer treatment to age-dependent changes in urinary, sexual, and bowel function remains unknown, given the absence of an untreated, age-matched control cohort.” This is a very important point, and I would add that the ideal control group would have been men with prostate cancer matched by age, baseline genitourinary and gastrointestinal function, and prostate cancer indices (prostate-specific antigen level, Gleason score, and T category) who underwent and stayed on active surveillance so an accurate assessment of the treatment effect on 15-year genitourinary and gastrointestinal function could be assessed. Without this control group, the comparative data on erectile dysfunction, which we know normally increases with age, are very hard to interpret. ■
Disclosure: Dr. D’Amico reported no potential conflicts of interest.
Dr. D’Amico is the Eleanor Theresa Walters Distinguished Professor of Radiation Oncology, Department of Radiation Oncology, Harvard Medical School, and Chief of Genitourinary Radiation Oncology at both Dana-Farber Cancer Institute and Brigham and Women’s Hospital, Boston.