Researchers develop tool to predict benefit of radiation therapy

During the next two decades, breast cancer diagnoses in older women are expected to increase by 57%. It's a reality that highlights the importance of understanding this demographic and the unique management decisions associated with their treatment.

New research led by Benjamin Smith, M.D., in the Department of Radiation Oncology, found that a clinical tool, or nomogram, demonstrates accuracy in predicting which women are likely to benefit from radiation therapy. The tool compiles readily available clinical and pathological data including age, race, tumor size and estrogen receptor status.

The study, published in the Journal of Clinical Oncology, examined 16,092 women ages 66--79 who were treated with breast-conserving surgery. The primary outcome was mastectomy-free survival (MFS) at five and 10 years. Overall, the five- and 10-year rates of MFS were 98.1% percent and 95.4% percent respectively.

"We thought it was relevant and interesting to look at the risk of mastectomy after initial treatment for breast cancer, see if radiation therapy made a difference and then develop a tool to individualize recommendations based on a person's risk profile," Smith said.

Individualizing Treatment

Beyond providing baseline estimates of MFS, the tool provides physicians with individual estimates for whom radiation therapy might, or might not be effective.

For example, a 75-year-old woman with a 1.5 cm ER-positive tumor and node-negative disease who underwent radiation therapy, yields an estimated 10-year MFS of 97%. However, if this same patient did not receive radiation therapy, the 10-year MFS rate would be 95%, suggesting radiation offers limited benefit.

Additional studies are needed to more accurately determine the risk of recurrence for certain subgroups of older populations.

"Although no nomogram is perfect, it's step forward to actually have a validated model based on the outcomes of 16,000 patients," Smith said.

Additional resources:

JCO study and podcast

MD Anderson news release