THE "NEW" PROSTATE CANCER INFOLINK

An article in this week’s New England Journal of Medicine offers us 15-year functional outcomes data from the Prostate Cancer Outcomes Study (PCOS), which enrolled 3,533 men in whom prostate cancer was diagnosed in 1994 or 1995.

The current paper (by Resnick et al.) is based on an analysis of data from about half of the men enrolled in this study. In these men, all aged between 55 and 74 years at time of diagnosis, functional status (including urinary, bowel, and sexual function status) was assessed at baseline and then at 2, 5, and 15 years post-diagnosis. All patients were treated with either surgery (n = 1,164) or radiotherapy (n = 491).

According to this analysis, there were two primary findings at 15 years of follow-up:

• There were no significant relative differences in disease-specific functional outcomes among men undergoing either radical prostatectomy or radiotherapy.
• Men treated for localized prostate cancer commonly had declines in all functional domains over the 15-year period.

The “New” Prostate Cancer InfoLink is unsurprised by these findings on long-term follow-up from men initially treated some 18-20 years ago. Decline in the urinary, bowel, and functional status of men who were between 70 and 89 years of age by the time they had been followed for 15 years would be normal based on the aging process. However, it should be emphasized that functional status at 2 years and at 5 years post-diagnosis did differ based on type of treatment — in exactly the ways that one might expect:

• At 2 years of follow-up
  • Men treated surgically were more likely to have urinary incontinence than men treated with radiotherapy (odds ratio [OR] = 6.22).
  • Men treated surgically were more likely to have erectile dysfunction than men treated with radiotherapy (OR = 3.46).
  • Men treated surgically were less likely to have bowel dysfunction than men treated with radiotherapy (OR = 0.39)
• At 5 years of follow-up
  • Men treated surgically were still more likely to have urinary incontinence than men treated with radiotherapy (OR = 5.10).
  • Men treated surgically were still more likely to have erectile dysfunction than men treated with radiotherapy (OR = 1.96).
  • Men treated surgically were less likely to have bowel dysfunction than men treated with radiotherapy (OR = 0.47)
• At 15 years of follow-up
  • There was no significant between-group difference among men treated surgically and men treated with radiation therapy with respect to urinary incontinence.
  • There was no significant between-group difference among men treated surgically and men treated with radiation therapy with respect to erectile dysfunction.
  • There was no significant between-group difference among men treated surgically and men treated with radiation therapy with respect to bowel function.

Of course the degree to which these data are really relevant to decisions about treatment today are arguable. There is little doubt that the quality of first-line treatment for localized prostate cancer today (surgically and using radiation therapy) is significantly higher than it was in 1994-95, and the majority of patients are probably being diagnosed earlier in the course of their disease. On the other hand, problems with continence and erectile function are still the most common side effects of surgical treatment and problems with bowel function are still common among men treated with radiation therapy.

The “New” Prostate Cancer InfoLink wishes to be clear that we have not had the chance to review the full text of this paper as yet, and our comments are based only on the data in the abstract, which is available on line.

We should point out that, at the annual meeting of the American Urology Association in Atlanta last year, Dr. Penson reported data from the 15-year follow-up of the same group of 1,655 men with respect to overall and prostate cancer-specific mortality. According to the data reported by Penson at that meeting (which has yet to be published in a peer-reviewed article), the men treated by radiation therapy had an overall mortality nearly twice as high (at 51 percent) than that of the men in the surgery group (28 percent). In addition, there was a threefold difference in the 15-year disease-specific mortality rate (12 percent for the radiation therapy patients as compared to 4 percent for the surgery patients). For a complete discussion of this report by Penson, see this article in Urology Times. There are all sorts of possible reasons for this significant difference in mortality rate, and the radiation oncology community would certainly argue that the patients treated by radiation therapy were potentially men who were more likely to have progressive disease. We look forward to being able to see a full published report of these data.

It also has to be noted that the Prostate Cancer Outcomes Study was not based on a prospective, randomized trial. It was based on a longitudinal, population-based study of patients from six of the Surveillance, Epidemiology, and End Results tumor registries in the USA. This raises all sorts of technical questions about the clinical reliability of the findings of the study (although the actual findings are not in dispute). The question is really just how meaningful they are for physicians and patients making decisions about the treatment of localized prostate cancer today.

Filed under: Diagnosis, Living with Prostate Cancer, Management, Risk, Treatment | Tagged: localized, outcomes, radiation, surgery, therapy |