Screen childhood cancer survivors for digestive, genitourinary neoplasms in adulthood

Childhood cancer survivors who develop subsequent primary neoplasms in adulthood are most likely to experience digestive and genitourinary cancers, so screening should focus on these two areas to reduce overall incidence, a British study found.

Researchers conducted the British Childhood Cancer Survivor Study, a population-based cohort of 17,981 patients diagnosed with cancer before age 15 who lived for at least 5 years from 1940 and 1991 and were followed through December 2006. Results appeared online June 8 in the Journal of the American Medical Association

The study found 1,354 subsequent primary neoplasms in 1,222 patients after a median follow-up of 24.3 years (mean, 25.6 years). The most commonly observed subsequent primary neoplasms were of the central nervous system (n=344), of which 105 were gliomas; nonmelanoma skin (n=278); digestive (n=105); genitourinary (n=100); breast (n=97); and bone (n=94).

Subsequent primary neoplasms occurred most frequently in survivors who were originally diagnosed with a central nervous system neoplasm (n=338), leukemia (n=271), Hodgkin's lymphoma (n=157), heritable retinoblastoma (n=131), and Wilms tumor (n=104).

Researchers compared standardized incidence ratios (SIRs), absolute excess risks (AERs), and cumulative incidence of subsequent primary neoplasms. The overall SIR was 3.9 (AER, 16.8 per 10,000 person-years). The AER at older than 40 years was highest for digestive (AER, 5.9 per 10,000 person-years) and genitourinary (AER, 6.0 per 10,000 person-years) subsequent primary neoplasms. These two types of cancer accounted for 36% of the total AER. The cumulative incidence of colorectal cancer for survivors treated with direct abdominopelvic irradiation was 1.4% by age 50 years, comparable with the 1.2% risk in individuals with at least two first-degree relatives affected by colorectal cancer.

When broken down by organ system:

• The SIR for genitourinary neoplasms was the lowest (SIR, 1.9; AER, 1.3/10,000 person-years).
• The SIR for a breast neoplasm was 2.2 times more than expected (AER, 1.4/ 10,000 person-years) and highest following Hodgkin's lymphoma (SIR, 8.9; AER, 7.8/10,000 person-years).
• The SIR for a digestive neoplasm was 4.6 times more than expected (AER, 2.2/10,000 person-years).
• The SIR for a glioma neoplasm was 6.5 times more than expected (AER, 2.4/10,000 person-years).
• The highest overall SIR was observed for bone neoplasms (SIR, 30.5; AER, 2.5/10,000 person-years).

Efforts to reduce development of subsequent primary neoplasms in childhood cancer survivors should focus on the digestive and genitourinary systems, the authors wrote. The results also provide evidence for routine colonoscopy in this population, they added.

Most childhood cancer survivors aren't routinely screened as adults, Annals of Internal Medicinereported last year. Women treated with chest radiation as children would benefit from breast cancer screening in adulthood, Annals also reported. Learn more about managing this patient population and how to encourage screening in ACP Internist's September 2010 cover article on the subject.