Colorectal risk defined for childhood cancer survivors
Survivors of childhood cancer may need to be screened for colorectal cancer earlier than current recommendations advise, especially if they had been exposed to abdominal radiation.
Researchers taking part in the National Cancer Institute's Childhood Cancer Survivor Study reached this conclusion based on data from 14,358 cancer survivors who had been diagnosed with Hodgkin lymphoma, non-Hodgkin lymphoma, neuroblastoma, soft tissue sarcoma, Wilms tumor, or bone cancer before reaching age 21 years; had been diagnosed between 1970 and 1986; and had survived for at least 5 years after initial diagnosis. While survivors of childhood cancer are known to develop gastrointestinal cancer more frequently and at a younger age than the general population, Tara O. Henderson, MD, MPH, of the University of Chicago (Illinois) Department of Pediatrics, Section of Hematology, Oncology and Stem Cell Transplantation, and colleagues sought to better characterize the factors associated with this risk.
Henderson's team identified 45 cases of gastrointestinal cancer at median follow-up of 22.8 years (range, 5.5 to 30.2 years). The risk for gastrointestinal subsequent malignant neoplasms (SMNs) was 4.6-fold higher among the survivors than in the general population, with risk being particularly high among survivors of Hodgkin lymphoma or Wilms tumor.
Survivors who had undergone abdominal radiation had the highest risk for gastrointestinal SMNs (standardized incidence ratio [SIR], 11.2). However, survivors with no exposure to abdominal radiation also had a significantly heightened chance of developing such neoplasms (SIR, 2.4).
Cancer treatment with high-dose procarbazine (relative risk, 3.2) and platinum drugs (relative risk, 7.6) also independently increased the risk for gastrointestinal SMNs.
Henderson and coauthors suggested in Annals of Internal Medicine (2012;156:757-766) that survivors of childhood cancer may benefit from undergoing screening for colorectal cancer every 5 years beginning 10 years after radiation or by age 35 years, whichever is later.