Childhood cancer survivors often face a range of long-term health complications due to their disease and its treatment, impacting their quality of life and lifespan. While the 5-year survival rate for childhood cancer has increased to approximately 85%, there is a need to understand the long-term health outcomes and causes of mortality beyond the first 5 years after diagnosis.
To address this issue, researchers conducted a retrospective cohort study using data from the Childhood Cancer Survivor Study, a multi-institutional, hospital-based study published in The Lancet. The study included 34,230 survivors of childhood cancer diagnosed at an age younger than 21 years from 1970 to 1999 at 31 institutions in the USA and Canada. The median follow-up from diagnosis was 29 years, ranging from 5 to 48 years.
The study found that 40-year cumulative all-cause mortality was 23.3% higher than the general population. Of the 5,916 deaths, 51.2% were from health-related causes (which excludes death from primary cancer and external causes and includes death from late effects of cancer therapy). This suggests that late mortality is a significant concern for childhood cancer survivors, with many deaths occurring beyond the first five years after diagnosis.
The study identified specific causes of health-related mortality in childhood cancer survivors. The top three causes of health-related death were cancer, heart disease, and cerebrovascular disease, also the leading causes of death in the general population. Survivors 40 years or more from diagnosis experienced 131 excess health-related deaths per 10,000 person-years, including those due to these three causes.
In addition, the study evaluated the impact of modifiable lifestyle and cardiovascular risk factors on health-related mortality in childhood cancer survivors. Healthy lifestyle habits, such as not smoking, moderate alcohol consumption, regular physical activity, and maintaining a healthy body mass index, were associated with a 20-30% reduction in health-related mortality independent of other factors. The absence of hypertension and diabetes also showed a similar reduction in risk.
These findings suggest that childhood cancer survivors are at excess risk of late mortality, with many of the leading causes of death in the general population contributing to this risk. Modifiable lifestyle and cardiovascular risk factors can significantly reduce the risk of health-related mortality in these survivors.
It is important to note that the study had some limitations. It did not account for the impact of cancer treatment on late mortality, and other factors not evaluated in this study may also contribute to excess risk. However, the study provides valuable insight into the long-term health outcomes of childhood cancer survivors.
It highlights the need for continued research and intervention efforts to improve outcomes for this population. Future interventions can focus on reducing modifiable risk factors and improving overall health and wellness in childhood cancer survivors, ultimately improving their quality of life and lifespan.