Reduced CAD risk noted over time in adult survivors of childhood cancer
Data from the Childhood Cancer Survivor Study were used to examine the cumulative incidence of reported heart failure, coronary artery disease (CAD), valvular heart disease, pericardial disease, and arrhythmias according to decade of treatment (1970s, 1980s, or 1990s).
Risk for coronary artery disease (CAD) in adults who have survived childhood cancer has decreased over the past three decades along with exposure to cardiac radiation during treatment, a study found.
Researchers analyzed data from the Childhood Cancer Survivor Study to examine the cumulative incidence of reported heart failure, CAD, valvular heart disease, pericardial disease, and arrhythmias according to decade of treatment (1970s, 1980s, or 1990s). Hazard ratios by decade and risks with and without exposure to cardiotoxic treatments were also determined. Participants had been treated for brain cancer, Hodgkin's lymphoma, non-Hodgkin's lymphoma, renal tumors, neuroblastoma, soft-tissue sarcomas, and bone sarcomas diagnosed before age 21 years between Jan. 1, 1970, and Dec. 31, 1999. The study also involved a comparison group of siblings of cancer survivors. The results were published by The BMJ on Jan. 15.
The current study included 23,462 participants in the Childhood Cancer Survivor Study at 27 institutions in the United States and Canada who had survived five years after a diagnosis of childhood cancer. Of these, 6,193 (26.4%) were treated in the 1970s, 9,363 (39%) were treated in the 1980s, and 7,906 (33.6%) were treated in the 1990s. Median age at diagnosis of cancer and median age at last follow-up were 6.1 years and 27.7 years, respectively, and 53.7% were men. The sibling comparison group included 5,057 people (52.3% women; median age, 32.8 years).
Twenty-year cumulative incidence of heart failure (0.69% for the 1970s, 0.74% for the 1980s, and 0.54% for the 1990s) and CAD (0.38%, 0.24%, and 0.19%) decreased in patients treated more recently. However, no decrease was seen for 20-year cumulative incidence of valvular disease (0.06%, 0.06%, and 0.05%), pericardial disease (0.04%, 0.02%, and 0.03%), or arrhythmias (0.08%, 0.09%, and 0.13%). Patients treated in the 1980s and 1990s had lower risk for heart failure, CAD, and valvular heart disease versus those treated in the 1970s, but this decrease was significant only for CAD (hazard ratio, 0.65 [95% CI, 0.45 to 0.92] for the 1980s and 0.53 [95% CI, 0.36 to 0.77] for the 1990s).
Overall risk for CAD was affected by adjustment for cardiac radiation in all participants (hazard ratio, 0.90; 95% CI, 0.66 to 0.89) and most notably in survivors of Hodgkin's lymphoma (unadjusted and adjusted hazard ratios, 0.77 [95% CI, 0.66 to 0.89] and 0.87 [95% CI, 0.69 to 1.10]). Traditional cardiac risk factors, namely dyslipidemia and hypertension, remained strongly associated with almost all cardiac outcomes after adjustment for personal factors, treatment-related factors, smoking, body mass index, and exercise.
The authors noted that their results should be considered in the context of decreased all-cause mortality rates over the past few decades among survivors of childhood cancer and that better survival and health screening among this population may have identified more cardiac events. They concluded that risk for CAD has significantly decreased among adult survivors of childhood cancer and that this decrease could be associated with historical reductions in cardiac radiation exposure.
“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 authors wrote. “Continued follow-up is needed to determine if these positive trends persist over time.”
The authors of an accompanying editorial noted that efforts to reduce cardiotoxicity of cancer treatment appear to be successful and should continue, but traditional risk factors must also be addressed. “Dyslipidaemia and hypertension remained strongly and independently associated with most cardiac outcomes, providing important insights to help inform preventative interventions for cancer survivors,” the editorialists wrote. They also stressed that risks and risk factors for survivors of childhood cancer are not necessarily the same as for survivors of young adult cancer and called for additional attention to survivorship issues, as well as better guidance regarding long-term follow-up.