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Reviewed research
Authors Resnick MJ, Koyama T, Fan KH, Albertsen PC, Goodman M, Hamilton AS, et al.
Review Date April 2013
Citation N Engl J Med 2013; 368: 436-45
Background
Survival rates after clinically localised prostate cancer are high regardless of the type of treatment chosen, with a median post-cancer life expectancy of about 14 years. It is therefore important to understand the functional outcomes from various treatments to help inform treatment decisions. Studies comparing prostatectomy and external-beam radiation therapy with short-term (up to 5 years) follow-up have shown some differences in functional status between treatments but the longer term outcomes had not been investigated before this study.
Aim
The purpose of this analysis of a large longitudinal study of prostate cancer outcomes was to compare long-term (15 years follow-up) urinary, bowel, and sexual function after radical prostatectomy with outcomes after external-beam radiation therapy.
Methods
The Prostate Cancer Outcomes Study (PCOS) is an American study that enrolled 3533 men in whom prostate cancer had been diagnosed in 1994 or 1995. The current cohort comprised 1655 men in whom localized prostate cancer had been diagnosed between the ages of 55 and 74 years and who had undergone either surgery (1164 men) or radiotherapy (491 men). Analysis included men who had completed the 2-year and/or the 5-year survey, as well as the 15-year follow-up. Functional status was assessed at baseline and at 2, 5, and 15 years after diagnosis. The main analysis was done with multivariable logistic regression (with adjustment for propensity scoring to control for non-random treatment assignment) to compare functional outcomes according to treatment.
Results
Men undergoing prostatectomy were more likely to have urinary incontinence than were those undergoing radiotherapy at 2 years (odds ratio [OR]=6.2; 95% confidence interval [CI]=1.9 to 20.3) and 5 years (OR=5.1; 95% CI=2.3 to 11.4). However, the odds of urinary incontinence at 15 years (OR=2.3; 95% CI=0.9 to 6.2) was not significantly elevated in the prostatectomy group. Similarly, although patients undergoing prostatectomy were more likely to have erectile dysfunction at 2 years (OR=3.5; 95% CI=1.9 to 6.2) and 5 years (OR=2.0; 95% CI=1.1 to 3.6), no significant between-group difference was noted at 15 years (OR=0.4; 95% CI=0.1 to 1.2). Men undergoing prostatectomy were less likely to have bowel urgency at 2 years (OR=0.4; 95% CI=0.2 to 0.7) and 5 years (OR=0.5; 95% CI=0.3 to 0.8), again with no significant between-group difference in the odds of bowel urgency at 15 years (OR=1.0; 95% CI=0.5 to 2.1).
Conclusion
At 15 years, no significant relative differences in disease-specific functional outcomes were observed among men undergoing prostatectomy or radiotherapy. Nonetheless, men treated for localized prostate cancer commonly had declines in all functional domains over 15 years.
Points to Note
- This study has extended previous prospective studies by following men for 15 years after treatment for localised prostate cancer, demonstrating deterioration in urinary, sexual and bowel function, irrespective of the initial treatment, with no statistically significant between-treatment group effects at 15 years.
- The sample size at 15 years was smaller than earlier surveys due to death and loss to follow-up and the attrition was different between groups, potentially introducing systematic bias. The authors attempted to control for this with imputation techniques but this does not completely rule out bias.
- The possible problem with sample size was evident where the odds of urinary incontinence for the prostatectomy group was 2.3 times that in the radiotherapy group, but the confidence interval crossed 1.0 (null effect) and thus was considered not significantly elevated.
- There was no control group in the study so it is difficult to separate treatment-related effects from age effects.
- Despite the limitations, the data should be of interest to men and their health professionals when deciding on treatment for localised prostate cancer.
- Quality of life and functional outcome studies are important to consider given the fact that men may live for many years following a prostate cancer diagnosis.
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