May 09, 2022
Compared to people without a history of cancer, survivors of the disease have a higher risk of developing another type at some point in their life.
While medical experts have known this fact for some time, it still isn't quite clear why it happens. Researchers have identified a variety of possible reasons, but they are complex and hard to prove. Unfortunately, one possible cause is the treatment for the primary cancer, though in many cases a definitive link can't be determined.
One study on adult cancer survivors found that lifestyle factors such as obesity and smoking may play a role in the increased risk of developing certain new or subsequent cancers.
The researchers said that survivors of a smoking-related primary cancer were more likely to develop a new cancer also related to smoking. The same trend was found with obesity. They said this emphasizes the importance of smoking cessation, weight management, physical activity and healthy eating in reducing the risk of developing some subsequent cancers.
Most prior studies have focused on childhood and adult cancer survivors. However, little attention has been given to the subsequent cancer risk of adolescent and young adult cancer survivors.
A new study has found that five-year survivors of adolescent and young adult cancer survivors in the U.S have a higher risk of developing and almost twice the risk of dying from a new primary cancer as the general population.
The study findings focused on the survivors of 29 adolescent and young adult cancers diagnosed between the ages of 15 and 39.
“These results strongly stress the need to expand research on and strengthen efforts for surveillance of subsequent cancers among childhood and adolescent and young adult cancer survivors, as well as develop age-specific, exposure-based, and risk-stratified prevention strategies in this growing population of survivors," said Dr. Hyuna Sung, lead author of the study and principal scientist of cancer surveillance research at the American Cancer Society.
The analysis included over 170,000 individuals in 9 surveillance, epidemiology and end results registries who survived five years since their initial cancer diagnosis that took place between 1975 and 2013.
The researchers found that 35 years post-cancer diagnosis, one in seven survivors developed new cancer and one in 16 survivors died from the new cancer. Overall, survivors compared with the general population had a 25% higher cancer incidence risk and a 84% higher risk for death.
Sung told Healio that the risk among the different types of initial cancer diagnoses varied.
“For example, the risk was five times higher among Hodgkin lymphoma survivors and about twofold higher among survivors of brain, head and neck, breast or colorectal cancers," Sung said. "This increased mortality reflects not just increased risk but also poor cancer survival when patients were treated for subsequent cancer."
She added that this large variation in risk suggests that cancer survivors not only have different risk factors but also undergo a range of treatments. This highlights the need for targeted prevention strategies with more opportunities for prevention and early detection of subsequent cancers.
The most common types of subsequent cancer Sung and her team found were female breast, lung and colorectal cancer. They made up 36% of all subsequent cancers and 39% of all subsequent cancer deaths. Lung cancer alone represented 11% of all subsequent cancers and 24% of all deaths from subsequent cancers.
Adolescent and young adult survivors of thyroid or melanoma cancer don't appear to have a higher risk than the general population, Sung said.
One of the few other studies that focused on adolescent and young adult cancer survivors found similar results. In the study, there were 12,321 subsequent primary cancer diagnoses in 11,565 survivors – most frequently among survivors of breast cancer, cervical cancer, testicular cancer and Hodgkin lymphoma.