Adult survivors of pediatric cancers appear to be experiencing fewer major cardiac events in adulthood partly because of reduced radiotherapy exposure, especially among survivors of Hodgkin lymphoma, recent research published in BMJ has shown.

“Contemporary cancer treatment has focused on advancing cure rates while attempting to minimize long term adverse effects,” Daniel A. Mulrooney, MD, of the Division of Cancer Survivorship, Department of Oncology, at St. Jude Children’s Research Hospital, Arlington, Va., and colleagues wrote. “Patterns of exposure to cardiotoxic treatment have changed over time, with fewer children receiving chest directed radiation, with lower doses and smaller volumes for those who do, and an increased use of anthracyclines, albeit with reduced cumulative doses as the risk for late-onset heart failure became apparent.”

Although research has been published on improved survival rates of children who underwent cancer treatment in the 1990s, compared with those who received treatment in the 1980s and 1970s, Dr. Mulrooney and colleagues set out to determine whether cardiac outcomes were reduced as well. They conducted a retrospective study of 23,462 5-year survivors of pediatric cancer, which consisted of leukemia, brain cancer, Hodgkin lymphoma, non-Hodgkin lymphoma, renal tumors, neuroblastoma, soft-tissue sarcomas, and bone sarcomas diagnosed between January 1970 and December 1999. Researchers compared the cardiac outcomes of the survivors, including heart failure, coronary artery disease, valvular heart disease, pericardial disease, and arrhythmias, with a comparison group of their siblings (n = 5,057) separated by decade. The adult survivors tended to be women (46% vs. 40%) with a median age of 6.1 years at diagnosis and 27.7 years at final follow-up.

Of the 6,193 participants treated for cancer in the 1970s, the 20-year cumulative incidence of heart failure was 0.69%, while the 9,363 participants treated in the 1980s had an incidence of 0.74%, and 7,906 participants in the 1990s had a cumulative incidence of 0.54% over 20 years. The 20-year cumulative incidence for coronary artery disease (CAD) was 0.38% for participants in the 1970s, 0.24% for participants in the 1980s, and 0.19% for participants in the 1990s (P less than .01). Researchers noted the 20-year cumulative incidence of valvular disease, pericardial disease, and arrhythmias did not decrease between the 1970s and the 1990s.

When comparing the rate of major cardiac events of participants in the 1980s and 1990s with those of the 1970s, CAD diagnoses significantly decreased in the 1980s (hazard ratio, 0.65; 95% confidence interval, 0.45-0.92) and 1990s (HR, 0.53; 95% CI, 0.36-0.77), while there was no significant decrease in heart failure or valvular heart disease risk over time. After adjusting for cardiac radiation, overall risk for CAD was attenuated (HR, 0.90; 0.78-1.05), and Hodgkin lymphoma survivors saw the greatest change between unadjusted (HR, 0.77; 95% CI, 0.66-0.89) and adjusted risk (HR, 0.87; 95% CI, 0.69-1.10) when accounting for cardiac radiation.

“While additional longitudinal follow-up is needed to establish whether similar reductions in the cumulative incidence of heart failure can be confirmed in multivariable analysis, 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,” the researchers concluded.

In a related editorial, Mike Hawkins, DPhil, of the Centre for Childhood Cancer Survivor Studies, Institute of Applied Health Research at the University of Birmingham (England), and colleagues said that, while measuring cardiotoxicity is important for this patient population, traditional risk factors with independent associations to cardiac outcomes should also be studied. Guidelines on follow-up for these patients are also needed to inform clinical practice, such as those produced by the International Late Effects of Childhood Cancer Guideline Harmonization Group, they added.

“Survivorship issues are extremely important to patients, their families, and their doctors,” they said. “In two research priority setting initiatives in the United Kingdom, detailed consultation with patients with cancer, survivors, families, friends, and healthcare professionals identified further research into the consequences of cancer as a top priority.”

This study was funded by grants from the National Cancer Institute, Cancer Center Support (CORE) to St. Jude Children’s Research Hospital and American Lebanese Syrian Associated Charities. The authors of the study and the editorial reported no relevant conflicts of interest.

SOURCE: Mulrooney A et al. BMJ. 2020. doi: 10.1136/bmj.l6794.