Childhood cancer survivors at risk for new cancers

NEW YORK (Reuters Health) - Survivors of childhood cancers have a markedly increased risk of developing new cancers later on, research indicates.

"The dramatic advances that have been made in the treatment of childhood cancer over the past several decades have created a large and growing population of long-term survivors," Dr. Peter D. Inskip and colleagues from the National Institutes of Health, Bethesda, Maryland, write in the International Journal of Cancer.

"Although many childhood cancers now can be cured, the aggressive therapies used are associated with increased risks of a variety of adverse health effects, including new primary cancers."

Inskip's team examined the risk of new cancers among children diagnosed with cancer between 1973 and 2002. They identified and followed a cohort of 25,965 children who survived at least 2 months.

A total of 433 new primary cancers were diagnosed in 400 subjects during the follow-up period. This represents a nearly six-fold increased risk of developing a new cancer among childhood cancer survivors relative to the general population.

The risks were similar for females and males, but were higher for blacks than whites.

The most common types of subsequent primary tumors included cancers of the breast, central nervous system, bone, thyroid gland, soft tissue, and skin. Leukemia also made the list.

Children at greatest risk of subsequent cancers included those initially diagnosed with a type of brain cancer called primitive neuroectodermal tumor, as well as those with retinoblastoma, Ewing sarcoma, and Hodgkin lymphoma.

The risk of subsequent solid cancers was higher among patients who were initially treated for childhood cancer with radiation therapy. The development of subsequent leukemia was strongly associated with receipt of chemotherapy.

"It will be of interest to determine whether the decreased use of radiation in the treatment of childhood cancers is accompanied by a reduced incidence of radiation-related second cancers," the investigator note.

SOURCE: International Journal of Cancer, November 15, 2007.