Abstract
Mortality after diagnosis of colorectal subsequent malignant neoplasms (CRC-SMN) among childhood cancer survivors is understudied. Using data from the Childhood Cancer Survivor Study (CCSS) and the Surveillance, Epidemiology, and End Results (SEER) program, we compared all-cause mortality of survivors with CRC-SMN with survivors without CRC-SMN and CRC patients in the general population without a childhood cancer history. Among 25 656 childhood cancer survivors, 96 developed CRC-SMN, with 50% diagnosed before age 40 years and 19% before age 30 years. Of those diagnosed before age 40 years, 35% had no prior abdominal- or pelvic-directed radiation therapy. The cumulative incidence of CRC-SMN in CCSS survivors was 0.7% (95% CI = 0.5% to 0.9%) by age 45 years and 1.1% (95% CI = 0.8% to 1.4%) by age 50 years. There were 31 deaths after CRC-SMN. Adjusted all-cause mortality was threefold higher (hazard ratio [HR] = 3.34, 95% CI = 2.25 to 4.59) than for survivors without CRC and statistically significantly higher for survivors diagnosed younger than age 30 years compared with SEER CRC patients (HR = 2.51, 95% CI = 1.29 to 4.89).