Survivors of childhood cancers are 5 to 10 times more likely than healthy siblings to develop heart disease by early adulthood, according to a presentation at the annual meeting of the American Society of Clinical Oncology. The findings came from the U.S. Childhood Cancer Survivor Study (CCSS).

"This study shows that childhood cancer survivors in their twenties are developing the kinds of heart disease we typically see in older adults," explained lead author Daniel A. Mulrooney, MD, assistant professor of pediatrics at the Masonic Cancer Center, University of Minnesota. "Our findings emphasize the need to educate patients, their families and other healthcare providers about the risk of delayed cardiovascular side effects of these otherwise life-saving cancer treatments, so that patients can be closely monitored after their treatment and appropriately followed as they age."

The U.S. study has the largest cohort of childhood cancer survivors in the world and has generated the greatest amount of data related to the long-term side effects of treatment. Previous CCSS analyses have shown that childhood cancer survivors have an increased risk of problems such as pulmonary fibrosis, congestive heart failure, blood clots and infertility, and more severe problems such as second cancers and kidney failure.

Today's treatments could potentially be safer, however, since many of them are more targeted. In the current study, the incidence of heart disease detected five or more years after cancer diagnosis was compared for 14,358 survivors of childhood leukemia, central nervous system tumors, Hodgkin's or non-Hodgkin's lymphomas, renal tumors, neuroblastoma, soft-tissue sarcomas or bone cancers who were originally diagnosed between 1970 and 1986 and 3,899 of their siblings.

Among survivors, researchers identified a higher incidence of a variety of cardiac conditions when compared with their siblings, including atherosclerosis (10 times greater risk), congestive heart failure (5.7 times greater risk), myocardial infarction (4.9 times greater risk), pericardial disease (6.3 times greater risk), and valvular disease (4.8 times greater risk).

The risks of various types of heart disease were two to five times greater in survivors who had anthracycline drugs (such as doxorubicin) or radiation therapy to the heart as part of their cancer treatment compared with survivors who did not undergo these treatments.

It is important to note that while the overall risk of heart problems among survivors was significantly higher than normal, the incidence of disease 30 years after diagnosis was low overall: 2 percent had atherosclerosis, 4 percent developed congestive heart failure, 1 percent had a myocardial infarction, 3 percent developed pericardial disease, and 4 percent had valvular heart disease.