The risk of serious heart conditions among adult survivors of childhood cancer has fallen since the 1970s, a study shows.
The researchers said the findings suggest that efforts to reduce exposure to the most toxic effects of anticancer treatment, including radiotherapy, seem to be working.
Many adult survivors of childhood cancer are at risk of early death and long term health conditions related to treatment. For example, cardiac radiation can cause heart and circulatory problems in later life.
In recent years, cancer therapy has focused on improving cure rates while trying to minimise long term adverse effects.
US researchers looked at whether these changes are associated with altered risks for cardiac events among adult survivors.
They analysed more than 23,000 adults from the Childhood Cancer Survivor Study who had survived the most common childhood cancers, diagnosed before age 21 and treated in the 1970s, 1980s and 1990s.
Using questionnaires, five cardiac conditions – heart failure, coronary artery disease (narrowing of arteries), heart valve defects (valvular disease), damage to the heart tissue lining (pericardial disease) and heart rhythm problems (arrhythmias) – were recorded.
Cardiovascular risk factors, such as diabetes, high blood pressure and cholesterol levels, smoking, exercise and weight, were also recorded.
The number of survivors exposed to cardiotoxic chemotherapy increased in more recent decades, but the proportion receiving higher doses decreased. Exposure to cardiac radiation declined from 77% of survivors treated in the 1970s to 40% treated in the 1990s, according to the study in The BMJ.
After taking account of potentially influential factors, the risk of coronary artery disease decreased from 0.38% in the 1970s to 0.24% in the 1980s and 0.19% in the 1990s. This was largely due to a strong decline among survivors of Hodgkin lymphoma.
The results also showed a decline in the risk of heart failure among patients treated in the 1990s, although it was not statistically significant.
The authors said it was an observational study, so cannot establish cause, and it relied on self-reported cardiac outcomes with almost a third of eligible survivors choosing not to participate.
However, they suggested that historical reductions in radiotherapy exposure appear to account for some of the decline in coronary artery disease, particularly among survivors of Hodgkin lymphoma.
“These results suggest that efforts to modify cancer therapies in children and promote health surveillance for survivors are beginning to show benefits not only in overall survival but also in late adverse cardiac effects,” they wrote.