Risk of Heart Disease Among Childhood Cancer Survivors Falls Since 1970s, Data Show

The risk of heart disease is falling among survivors of childhood cancer, data show.

The journal BMJ reports Wednesday that efforts to protect children from the most toxic effects of cancer treatment, such as radiotherapy, appear to be working. Risk of coronary artery disease (CAD) fell steadily, from 0.38% in the 1970s to 0.19% by the end of the 1990s.

The findings are based on results from 23,462 adults in the Childhood Cancer Survivor Study who had the most common cancers diagnosed before age 21 from the 1970s through the 1990s. The median age at diagnosis was 6.1 years of age, and the mean age at the last follow-up was 27.7 years. A comparison group 5067 siblings of cancer survivors was also included.

While the number of survivors who had cardiotoxic treatments increased, the doses they received decreased. Radiation exposure fell from 77% in the 1970s to 40% in the 1990s.

Survivors of Hodgkin lymphoma accounted for most of the decline, and efforts to reduce radiotherapy among these patients likely explain the drop, the researchers report.

“These results suggest that efforts to modify cancer therapies in children and promote health surveillance are beginning to show benefits not only overall survival but also in late adverse cardiac effects,” the authors concluded.

The study asked questions about 5 cardiac conditions—heart failure, coronary artery disease, heart valve defects, damage to heart tissue lining, and arrhythmias—and recorded the results. The researchers also recorded whether participants had risk factors such as diabetes, high blood pressure, or elevated levels of low-density lipoprotein cholesterol, whether they smoked or exercised, and their weight.

The 20-year incidence of heart failure first rose from 0.69% in the 1970s to 0.74% in the 1980s, before falling to 0.54% for those treated in the 1990s.

To no surprise, having traditional cardiac risk factors fueled the risk of heart disease among cancer survivors, demonstrating the need for prevention of heart problems among this group. One problem with the study is that almost a third of possible participants opted not to answer the questionnaire, which could have affected the results.

As the number of cancer survivors increases, collaboration between oncologists and cardiologists is increasing to better protect patients from late effects of treatment. Although heart failure results were not considered statistically significant in this study, heart failure is considered a risk of cancer treatment generally, as noted in 2019 by Kostakou et al.

“If heart failure develops, even in the absence of overt clinical symptoms, standard heart treatment is to be followed and causal agent discontinued if possible,” the authors wrote in Heart Failure Reviews. “One important question is whether and when to stop cardiac medication in case of heart dysfunction reversal, after completion of cancer treatment.

“Further cardio-oncology evolution can lead to a deeper understanding of the adverse mechanisms and effects causing heart failure, as well as the development of personalized treatment regimens in order to limit cardiotoxicity.

Reference

Mulrooney DA Hyun G, Ness KK, et al. Major cardiac events for adult survivors of childhood cancer diagnosed between 1970 and 1999: report from the Childhood Cancer Survivor Study cohort. BMJ Open. 2020;368:16794. http://dx.doi.org/10.1136/bmj.l6794.