Purpose: To investigate the incidence of undiagnosed, asymptomatic synchronous colorectal cancer (CRC) by using screening colonoscopy before brachytherapy, and to compare the subsequent rates of CRC and rectal toxicity in this screened population with those rates in unscreened patients after brachytherapy.
Methods and materials: Patient, disease, and treatment characteristics, including history of colonoscopy and CR malignancy, were extracted from the medical records of all men who had undergone brachytherapy as monotherapy for low- or intermediate-risk prostate cancer at a single tertiary cancer care center between January 2000 and December 2009. The frequency of biopsy or polypectomy at screening colonoscopy, incidence of CR malignancy before and after prostate cancer diagnosis, and rate of brachytherapy toxicity including rectal bleeding were compared between men who had had screening colonoscopy before brachytherapy and men who had not.
Results: Of the 451 men identified, 268 had undergone screening colonoscopy during the 36 months before brachytherapy and 183 had not. Of the 268 men who had had screening colonoscopy, 117 (44%) underwent biopsy or polypectomy, and 6 (3.2%) were found to have asymptomatic CRC. After brachytherapy, CRC was diagnosed in 3 (1.6%) of the 183 men who had not had screening colonoscopy before treatment versus 0 of the 268 men who had had screening colonoscopy (P = 0.035). Rectal toxicity was more common and more severe among men who had not undergone screening colonoscopy compared with those who had had screening colonoscopy before brachytherapy (14% vs 6%, P = 0.003). More unscreened patients (18% vs 5%) underwent postbrachytherapy colonoscopy (P < 0.001), with the potential of subjecting the irradiated rectum to biopsy.
Conclusions: More than 3% of men with newly diagnosed prostate cancer in this study presented with undiagnosed, asymptomatic CRC, and the rate of postbrachytherapy rectal complications was higher among unscreened than among screened patients. We recommend screening colonoscopy for men who have not had CRC screening within the 3 years preceding prostate cancer diagnosis before radiation therapy to avoid unnecessary rectal biopsies and the associated risk of major complications.
Copyright © 2012 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.