Children who survive cancer are more likely to develop another tumor later in life, a new study of nearly 18,000 cancer survivors found.
Researchers followed 17,981 cancer survivors who were first diagnosed before the age of 15 over 25 years. During that time, 1,354 new tumors (neoplasms) were found in 1,222 of the survivors. The most common tumors, the study revealed, involved the central nervous system, followed by non-melanoma skin cancer.
Overall, researchers concluded survivors were four times more likely than expected to develop another tumor later in life.
In adults older than 40, the greatest additional risk was for a new tumor — either malignant or benign — of the digestive, genital or urinary tract organs, researchers found.
Survivors were more likely to develop a subsequent tumor as they grew older — from 1.6 percent at age 20 to 13.8 percent at age 60 (compared to just 8.4 percent of 60-year-olds in the general population.)
The survivors were also at increased risk of developing a tumor at younger ages. By age 38, 5 percent of the childhood cancer survivors had developed a new tumor. For a group drawn from the general population, it would take until age 54 for 5 percent to develop a tumor.
The researchers also found that 1.4 percent of those studied whose childhood cancer was treated with direct irradiation near their abdominal and pelvic region developed colorectal cancer by the time they were 50 years old — roughly the same risk as people who have at least two first-degree relatives with this disease.
“These increased risks of digestive subsequent [tumors] are likely to be related to previous exposure of the digestive tract to radiation,” according to the study’s authors. They concluded there may be a need for childhood cancer survivors treated with direct abdomino-pelvic irradiation to be considered for routine colonoscopy screening for colorectal cancer.
The researchers added, however, genetic predisposition is also at least partly to blame for the added tumor risk in childhood cancer survivors. The study, published in the June 8 issue of theJAMA, also noted that the magnitude of the risk in the aging process is still unclear.
The National Cancer Institute provides detailed information on current trends in childhood cancer.