Mining Surveillance Data: Does Radiation Treatment of Prostate Cancer Cause Rectal Cancer?

Prostate cancer (PC) is the most common invasive cancer among males, with most cases organ-confined at diagnosis. External beam radiation (RAD) and prostatectomy (SURG) represent the most common treatments for organ-confined PC, with RAD exposing the rectum to high-dose ionizing radiation. Using the California population for 1988-2009, we identified men treated with RAD and SURG for organ-confined PC and assessed the hazards ratio for rectal cancer five or more years following PC treatment. The adjusted Cox proportional hazards ratio was 39% higher for rectal cancer in the RAD cohort. Further analyses seek to distinguish roles of RAD dose and delivery