Children and young people who survive cancer have a significantly higher risk of developing heart disease as young adults because of the cancer treatment they received, researchers said Wednesday.

A study by doctors from the United States found that young adult survivors of childhood cancer are at risk of a range of cardiac problems such as heart failure, heart attacks, or heart disease and the risks continued up to 30 years after treatment.

Young adults who survive childhood or adolescent cancer are clearly at risk for early cardiac morbidity and mortality not typically recognized within this age group, said Daniel Mulrooney from the University of Minnesota, who led the study.

He said numbers of cancer survivors were likely to increase as treatments and success rates improved and these patients would need careful cardiac monitoring, particularly as they get nearer the age when heart problems become more prevalent.

The researchers compared data from more than 14,350 five year cancer survivors taking part in a childhood cancer survivor study with around 3,900 siblings of cancer survivors.

The cancer survivors had been diagnosed below the age of 21 with either leukemia, brain cancer, Hodgkin's lymphoma, non-Hodgkin's lymphoma, kidney cancer, neuroblastoma, soft tissue sarcoma, or bone cancer between 1970 and 1986.

The study found the cancer survivors were significantly more likely than siblings to report heart failure, heart attacks or heart disease.

Those who had been treated with chemotherapy had a two to five times higher risk than those who had no chemotherapy. Radiation exposure also increased the risk by two to six times compared to those who had not had radiotherapy.

Healthcare professionals must be aware of these risks when caring for this growing population, said Mulrooney.

In a commentary on the research which was published in the British Medical Journal, Meriel Jenney, a pediatric oncologist from Cardiff children's hospital, said a recent study of French and British patients found a six-fold increase in cardiac deaths in cancer survivors compared with the general population.

She noted that British guidelines on long-term follow-up for cancer survivors recommend routine heart screening every five years, while in the United States screening is more frequent for those judged to be at greater risk.