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Title: Second malignancies after prostate brachytherapy: Incidence of bladder and colorectal cancers in patients with 15 years of potential follow-up

Journal Article · · International Journal of Radiation Oncology, Biology and Physics
 [1];  [2];  [3];  [4];  [4]
  1. Department of Radiation and Cellular Oncology, University of Chicago Pritzker School of Medicine, Chicago, IL (United States)
  2. Seattle Prostate Institute at Swedish Hospital, Seattle, WA (United States) and Swedish Cancer Center at Stevens Hospital, Edmonds, WA (United States)
  3. Department of Radiation Oncology, University of Florida, College of Medicine, Gainesville, FL (United States)
  4. Seattle Prostate Institute at Swedish Hospital, Seattle, WA (United States)

Purpose: To report the incidence of second bladder and colorectal cancers after prostate brachytherapy. Methods and Materials: This review included 125 patients treated with I-125 brachytherapy alone, and 223 patients who received supplemental external beam radiation therapy. Median follow-up was 10.5 years. Patients were followed for the development of lower genitourinary and colorectal cancers. Second malignancies arising five years after radiation therapy were defined as being potentially associated with treatment; observed rates were then compared with age-matched expected rates according to Surveillance, Epidemiology, and End Results data. Results: Five years out of treatment, there were 15 patients with a second solid tumor, including bladder cancer (n = 11), colorectal cancer (n = 3), and prostatic urethra cancer (n = 1). The incidence of second malignancy was no different in patients treated with brachytherapy alone (1.6%) vs. those receiving external beam radiotherapy (5.8%, p = 0.0623). There were more observed bladder cancers compared with those expected (relative risk, 2.34, 95% confidence interval 0.96-3.72; absolute excess risk 35 cancers per 10,000 patients). Relative risk did not significantly change over increasing follow-up intervals up to 20 years after treatment. Conclusions: There may be an increased but small risk of developing a second malignancy after radiation therapy for prostate cancer. This outcome could be related to radiation carcinogenesis, but more vigilant screening and thorough workup as a result of radiation side effects and predisposing conditions (e.g., genetic and environmental factors) in many of the patients found to have second malignancies likely contributed to the higher number of observed malignancies than expected.

OSTI ID:
20850148
Journal Information:
International Journal of Radiation Oncology, Biology and Physics, Vol. 66, Issue 3; Conference: 48. annual meeting of the American Society for Therapeutic Radiology and Oncology, Pennsylvania, PA (United States), 5-9 Nov 2006; Other Information: DOI: 10.1016/j.ijrobp.2006.05.016; PII: S0360-3016(06)00938-2; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
Country of Publication:
United States
Language:
English