Childhood cancer survivors develop gastrointestinal malignancies more frequently and at a younger age than the general population, but risk factors for their development have not been well characterized.
To determine the risk and associated risk factors for gastrointestinal subsequent malignant neoplasms (SMN) in childhood cancer survivors.
Retrospective cohort study.
The Childhood Cancer Survivor Study, a multi-center study of childhood cancer survivors diagnosed between 1970 and 1986.
14,358 survivors of a malignancy diagnosed at < 21 years who had survived for 5 or more years from initial diagnosis.
Standardized incidence ratios (SIR) for gastrointestinal SMN were calculated using age-specific population data. Multivariate Cox regression models identified associations between risk factors and gastrointestinal SMN development.
At median follow-up of 22.8 years (range: 5.5-30.2), 45 gastrointestinal malignancies were identified. Gastrointestinal SMN risk was 4.6-fold higher in childhood cancer survivors than the general population (95% confidence interval [CI]: 3.5-6.1). Colorectal cancer SIR was 4.2 (95% CI: 2.8-6.3). The highest gastrointestinal SMN risk was associated with abdominal radiation (SIR=11.2, 95% CI: 7.6-16.4). However, survivors not exposed to radiation had a significantly increased risk (SIR=2.4, 95% CI-1.4-3.9). In addition to abdominal radiation, high dose procarbazine (RR=3.2, 95% CI 1.1-9.4) and platinum drugs (RR 7.6, 95% CI: 2.3-25.5) independently increased the gastrointestinal SMN risk.
This cohort has not yet attained an age at which gastrointestinal malignancy risk is greatest.
Childhood cancer survivors, particularly those exposed to abdominal radiation, are at increased risk for gastrointestinal SMN. These findings suggest that surveillance of at-risk childhood cancer survivors should commence at a younger age than recommended for the general population.