Biological Aging and Radiation Therapy for Breast Cancer

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Some patients who have received treatment for breast cancer may experience increased biological aging compared with those who have never been diagnosed with breast cancer, according to a new study published by Kresovich et al in the Journal of the National Cancer Institute. The findings showed that the association was most pronounced among patients who received radiation therapy, whereas surgery showed no association with biological aging—indicating that developing cancer may not be responsible for the aging effect.


Biological age reflects the cell and tissue health of an individual and often differs from their chronologic age.

In the new study, researchers sought to measure the biological age of 417 patients from the Sister Study—a research initiative established to identify environmental risk factors contributing to the risk of breast cancer and other diseases—by examining blood samples taken from them at two time points about 8 years apart. About 50% of the patients involved in the study developed breast cancer during the time span.

The researchers then utilized three different “methylation clocks” to analyze naturally occurring chemical modifications in the patients’ DNA and identify changes in their biological ages between the two time points. The researchers were also able to detect small variations in methylation patterns to help them determine the patients’ risk of developing age-related diseases.

They found that patients who were diagnosed with breast cancer had faster aging rates according to all three clocks—with no significant race-related differences—compared with patients who did not develop breast cancer.

Further, the researchers assessed whether biological age was associated with specific treatment regimens such as surgery, chemotherapy, radiation therapy, and endocrine therapy.  Among the patients who had breast cancer, aging rates varied by treatment type.

“Of the three treatment classes we looked at, radiation therapy had the strongest associations with the [biological] age measures assessed in the study,” explained senior study author Jack Taylor, MD, PhD, Leader of the Molecular & Genetic Epidemiology Group and a scientist Emeritus at the National Institute of Environmental Health Sciences (NIEHS). “The increases can be detected years after treatment,” he added.


“Radiation is a valuable treatment option for [patients with] breast cancer, and we don’t yet know why it was most strongly associated with biological age,” emphasized co–study author Dale Sandler, PhD, Chief of the Epidemiology Branch at the NIEHS. “This finding supports efforts to minimize radiation exposures when possible and to find ways to mitigate adverse health effects among the approximately 4 million breast cancer survivors living in the United States,” she highlighted.

The researchers discouraged patients from abandoning radiation therapy as a result of their new findings. Current breast cancer treatments that include radiation have been shown to be very effective in preventing breast cancer from spreading.

“[Patients] faced with breast cancer diagnoses should discuss all possible treatment options with their [physicians] to determine the best course of treatment for them,” concluded co–study author Katie O’Brien, PhD, a staff scientist in the Epidemiology Branch at the NIEHS.

Disclosure: For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.