For decades, the narrative of childhood cancer has been one of remarkable medical triumph. Thanks to advancements in chemotherapy, radiation, and surgical techniques, the five-year survival rate for pediatric malignancies has climbed to over 80%. However, for the hundreds of thousands of survivors now reaching adulthood, that initial victory often comes with a persistent shadow: the risk of developing a second, unrelated cancer later in life.
While the medical community has long recognized that the very treatments used to save a child’s life can sow the seeds of future illness, the exact interplay between those treatments, a patient’s lifestyle, and their underlying genetic makeup has remained difficult to untangle. Now, a landmark study from St. Jude Children’s Research Hospital has provided the most comprehensive quantification to date of how these various factors contribute to the risk of secondary cancers.
The research, published today in The Lancet Oncology, offers a paradigm-shifting look at the long-term health of survivors. By analyzing data from two of the world’s most significant survivor cohorts, scientists have demonstrated that a survivor’s genetic predisposition can be just as influential—and in some cases, more influential—than the chemotherapy they received years prior.
Comparing contributions to second cancers in survivors
Secondary cancers are not merely a side effect; they represent the leading cause of non-relapse mortality for long-term survivors of childhood cancer. Understanding why some survivors develop these malignancies while others do not is critical for evolving the standard of follow-up care.
"We found the burden of second cancer in survivors of childhood cancer is largely contributed by pediatric treatment exposures and genetic predisposition," said the study’s corresponding author, Yadav Sapkota, PhD, of the St. Jude Department of Epidemiology and Cancer Control. "We’ve known treatment exposures and genetics were associated with second cancer risk, but this is the first time we’ve been able to attribute the proportion of their contributions to that risk at the population level."
To reach these conclusions, the research team utilized an unprecedented depth of data. They drew from the St. Jude Lifetime Cohort Study (St. Jude LIFE) and the Childhood Cancer Survivor Study (CCSS), which together represent the largest and most thoroughly documented survivor cohort in North America. By examining more than 10,000 survivors, the researchers were able to cross-reference detailed treatment records with genetic sequencing, lifestyle surveys, and long-term health outcomes.
The scale of the study was a vital component of its success. "This kind of high-impact discovery is only possible in the CCSS and SJLIFE cohorts, that in combination, have more than 12,000 survivors with genetic sequencing," noted co-author Greg Armstrong, MD, MSCE, chair of the St. Jude Department of Epidemiology and Cancer Control.
The most prominent factor identified in the study was radiation exposure. According to the data, radiation remains the most significant contributor to secondary cancer risk, accounting for approximately 40% or more of the risk observed in the population. This finding reinforces decades of clinical observation regarding the long-term adverse effects of ionizing radiation on developing tissues.
