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Adult heart disease after childhood cancer now less likely

Efforts to cut toxicity of treatment credited for drop in heart disease risk in survivors of childhood cancer

Louise Prime

Thursday, 16 January 2020

The risk of someone who had cancer as a child going on to develop heart disease as an adult have fallen over the past few decades, research has shown. The researchers behind the study,* conducted among thousands of people treated since the 1970s and published today in the BMJ, said the decline is associated with efforts to reduce cardiotoxic exposure in children.

The US research team conducted a retrospective cohort study to investigate the impact on serious cardiac outcomes among adult survivors of childhood cancer of modifications to contemporary cancer protocols, that were designed to minimise cardiotoxic exposures and preserve long-term health.

They analysed data from 27 institutions taking part in the Childhood Cancer Survivor Study, covering outcomes among 23,462 people who had been diagnosed in the 1970s, 1980s and 1990s, at up to 21 years old (median 6.1 years old), and treated for leukaemia, brain cancer, Hodgkin lymphoma, non-Hodgkin lymphoma, renal tumours, neuroblastoma, soft tissue sarcomas, and bone sarcomas – and who had survived for at least five years following treatment.

The researchers reported that overall, the 20-year cumulative incidence of both heart failure and coronary artery disease fell over time from the 1970s and 1980s to 1990s (from 0.69% to 0.74% to 0.54%, and from 0.38% to 0.24% to 0.19% respectively). However, they did not find any statistically significant change for valvular disease, pericardial disease or arrhythmias.

After they had adjusted for age at diagnosis, race, sex, body mass index, smoking, exercise intensity, and modifiable risk factors such as diabetes, dyslipidaemia, and hypertension, they found that the hazard ratios (HR) of heart failure and coronary artery disease still declined over five year treatment eras – but only the decline for coronary artery disease (HR 0.80) achieved statistical significance. They said: “This finding was attenuated by adjustment for exposure to cardiac radiation (HR 0.90), suggesting that decreases in radiation dose or changes in modalities or delivery methods might account for some portion of the treatment era risk for coronary artery disease.”

The study authors suggested that the significant decrease over time in coronary artery disease among adult survivors of childhood cancer could be associated with historical reductions in exposure to cardiac radiation, particularly among survivors of Hodgkin lymphoma. They noted: “This is important as childhood cancer survival rates increase and these young adults prematurely acquire cardiovascular disease.”

They concluded: “Historical reductions in exposure to cardiac radiation have been associated with a reduced risk of coronary artery disease among adult survivors of childhood cancer. Additional follow-up is needed to investigate risk reductions for other cardiac outcomes.”

The authors of an accompanying editorial** welcomed the fact that efforts to reduce cardiotoxicity in more recent decades seem to be having a measurable effect, and said these should continue. But they added: “It remains critically important to also address traditional risk factors, given their powerful independent relation with cardiac outcomes in this and other studies.”

* 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 2020; 368: l6794 DOI: 10.1136/bmj.l6794A

** Hawkins M, Brownsdon A, Reulen R. Falling risk of heart disease among survivors of childhood cancer. BMJ 2020; 368: m58. DOI: 10.1136/bmj.m58

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