Patient-reported long-term rectal function after permanent interstitial brachytherapy for clinically localized prostate cancer

Purpose: To evaluate the effect of permanent interstitial brachytherapy with or without supplemental therapies on long-term rectal function using a patient-administered quality-of-life instrument.

Methods and materials: One hundred thirty four of the initial 219 prostate brachytherapy patients who remain alive and have participated in a prospective evaluation of rectal function were mailed the rectal function assessment score (R-FAS). Of the 134 patients, 3 have a colostomy because of colorectal cancer, 2 failed to respond, and 129 (99.2% of eligible patients) returned a completed R-FAS. R-FAS ranges from 0 to 27 with lower scores indicative of better bowel function. Median followup was 14 years. Multiple clinical, treatment, and dosimetric parameters were evaluated for impact on bowel function.

Results: For the current cohort, R-FAS was 3.35, which was comparable to the 1999 (4.29), 2002 (3.92), and 2006 (4.00) surveys. In the 2011 survey, 10 (7.8%), 17 (13.1%), and 102 (78.3%) patients reported bowel function to be worse, improved, or unchanged after brachytherapy. No patient has developed a rectal ulcer or fistula. The number of preimplant bowel movements, tobacco, and diabetes mellitus correlated with R-FAS. Consistent with the previous thee surveys, patient's perception of overall rectal quality of life was inversely related to the use of supplemental external beam radiation.

Conclusions: Long-term rectal function after prostate brachytherapy is favorable with a small number of patients reporting deterioration in bowel function. The judicious use of supplemental external beam radiation with particular attention to rectal doses may further improve long-term function.