Genetic tests for cancer helps doctors and patients figure out the best targeted therapy matched to the tumor’s mutations. But the tests leave questions hanging about radiation therapy — until now.
The new message is: You can carry on with standard of care for radiation therapy, with a few extremely rare exceptions,” said
Sarah Kerns, Ph.D., M.P.H., a
Wilmot Cancer Institute investigator and expert in
radio genomics, a relatively new area of cancer research that focuses on the link between radiation therapy and genomics.
Patients sometimes come to their radiation treatment consultation with genetic testing results in hand — a list of up to 50 gene mutations that may or may not have significance to their treatment plan. Some mutations are acquired by the cancer, but others are present in all cells in the body, leaving the patient concerned about whether the results mean their normal, healthy tissue might be impacted by radiation.
The short answer is no, Kerns said. She was part of a nationwide group that reviewed the scientific literature and found that the mutations from conventional sequencing panels do not point to a higher risk of radiation toxicity.
The findings were published by
the International Journal of Radiation Oncology, Biology, Physics.
The group, which was convened in 2019 by the American Society of Radiation Oncology, decided that currently no action is needed by doctors or patients. But they also urged research to continue.
Kerns’ studies are focused on genome-wide analysis instead of the narrower tumor-gene sequencing. The broader approach allows her to test gene mutations that occur in any gene that might be important for radiation sensitivity of normal tissue surrounding tumors. Most often, it’s the normal tissue that is damaged and results in painful and harmful side effects from radiation treatment.
Common toxicities, for example, can include changes in bladder and bowel habits or gastrointestinal trouble following prostate cancer radiation therapy. For head and neck cancers, radiation side effects can cause mouth pain and difficulty swallowing, and for lung cancer, the treatment toxicity can result in inflammation and trouble breathing.
“Most likely, we will discover through research that much of the genetic source of treatment toxicity will be a cumulative effects of lots of small gene changes,” Kerns said. “It’s like looking for lots of needles in a haystack. But importantly, the consensus of the panel is that the mutations included in the cancer genetic tests do not, by and large, put patients at higher risk for toxicity.”
“Most likely, we will discover through research that much of the genetic source of treatment toxicity will be a cumulative effects of lots of small gene changes,” Kerns said. “It’s like looking for lots of needles in a haystack. But importantly, the consensus of the panel is that the mutations included in the cancer genetic tests do not, by and large, put patients at higher risk for toxicity.”
