The good news is that children who are treated for soft tissue sarcomas are surviving longer than they have in the past. However, this places them at increased risk for second cancers, especially when the initial treatment is a combination of radiation and chemotherapy.

These are the results of a new analysis of data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute, which are published in the medical journal Cancer.

Although other studies have suggested an increased cancer risk in this population, they have been small in size, Dr. Rochelle E. Curtis, at the National Cancer Institute in Bethesda, Maryland, and her associates note.

They therefore conducted a large study to follow 1,499 children who survived for at least one year after a soft tissue sarcoma diagnosis between 1973 and 2000. The cancer types included Rhabdomyosarcoma, fibromatous tumors, or other soft tissue sarcomas. The rates of malignancy were compared with those expected in the general population based on gender, race, age and calendar year.

Overall, 27 children developed 28 second primary cancers, compared with the expected 4.5 cases. The most common second malignancies included acute myeloid leukemia, cutaneous melanoma, and cancers of the oral cavity, breast, bone, and soft tissue.

The relative risk was higher during the first five years of follow-up, about 12 times higher than expected, but decreased to 5-times thereafter.

Other factors associated with higher risk included treatment since 1985 rather than earlier, age younger than 10 years old, and combined radiotherapy and chemotherapy versus surgery alone.

The risk associated with combined therapy was highest for patients with malignancies formed by fibrous tissue. The rate of second cancers in these patients was increased by more than 70-fold, the authors note.

“Further studies of childhood soft tissue sarcoma survivors are needed to evaluate the independent and combined effects of therapy and genetic susceptibility in the development of various types of second cancers,” Curtis’s group concludes.

SOURCE: Cancer, June 1, 2005.