Childhood cancer survivors have a higher risk of developing cancer than other people.
Second cancers are a common late effect of childhood cancer treatment, especially after radiation. A late effect is a side effect of treatment that happens months or years after cancer treatment is over.
Scientists are studying new ways to estimate your chance of cancer. One way is using the polygenic risk score to estimate second cancer risk. Researchers led by Yadav Sapkota, PhD, of St. Jude Children’s Research Hospital, studied how certain risk factors had an impact on childhood cancer survivors having a second cancer. Their research is based on information from the Long-Term Follow-Up (LTFU) and the St. Jude LIFETIME Cohort (St. Jude LIFE) studies.
To assess the impact of certain factors on cancer risk, the team assigned numbers to different risk factors. They looked at how chemotherapy, radiation, genes, and lifestyle habits affected a person’s risk of having a second cancer. Researchers used this information to estimate cancer risk. The research was published in the journal Lancet Oncology.
“We created a score that shows the cumulative effect of the factors that influence risk of cancer,” Sapkota says.
Factors that increase cancer risk
Radiation and chemotherapy lead to about 50% of second cancers that happen during adulthood, Sapkota says. The study found that radiation exposure was the strongest predictor of cancer risk. The study also found that changes (mutations) in genes were often the second strongest factor. In some patients, chemotherapy was a stronger predictor.
“Genetics were not a stronger predictor than radiation, but sometimes they were greater than chemotherapy alone,” Sapkota says. “That was a major finding of the study.”
Scientists calculated the genetic part of the risk score based on information in DNA. DNA is like a set of instructions inside your cells. It tells your body how to grow, work, and stay healthy. Scientists learned more about DNA by testing it from blood or saliva samples from people who took part in the study. This testing gathered details about genes. It looked for small changes that may lead to cancer.
Genes are segments of DNA. They are passed down through your parents. They help decide things like eye color. They also affect your risk for certain diseases, including cancer. For example, mutations in BRCA genes increase a person’s risk of breast cancer.
How polygenic risk scores might help
Researchers hope that tools like polygenic risk scores can help make decisions about your health in the future. If your risk score is available and shows a high chance of cancer, that information may affect your care provider’s recommendations. Your providers could recommend early screening for certain types of cancer depending on what is found.
“The polygenic risk score is a powerful tool, but it is not a 100% guarantee of whether you will develop cancer or not,” Sapkota says. “But it may help you make decisions about your health.”
When screening tests are available, knowing who is at the highest risk could make a big difference in treatment and outlook for a second cancer. In general, cancer is more treatable the earlier it is found.
Ask your primary care provider about your risk of having a second cancer. Talk to them about genetic testing and other ways to understand your cancer risk. Understanding your risk can help you take steps toward better health.