A New Risk Calculator for Radiotherapy in Older Women With Early-Stage Breast Cancer

Researchers have developed a risk calculator that has the potential to help better inform older women with early-stage breast cancer about the risks and benefits of radiotherapy. The tool is called the Radiotherapy for Older Women (ROW) risk calculator and it combines 2 existing prediction models, the Early Breast Cancer Trialist Collaboration Group prediction model for breast cancer specific outcomes and ePrognosis for life expectancy. While the tool needs to be perfected and validated, these initial findings were presented at the 2019 San Antonio Breast Cancer Symposium.

Studies have shown that radiotherapy tends to reduce local recurrence, but does not improve overall survival (OS) in many older women with early-stage breast cancer. For this reason, researchers developed and validated a new risk calculator just for older women that seeks to predict 5-year and 10-year risks of local recurrence and mortality. The ROW risk calculator makes its predictions based on age, comorbidities, functional status, tumor characteristics, and use of radiotherapy.

To validate their tool, the researchers collected clinical data from all women older than 65 with newly diagnosed stage I/II breast cancer between 2001 and 2010 at the Yale Cancer Center in New Haven, Conneticut. The team then conducted a simulation and found that the 5-year all-cause mortality estimated by ROW ranged from 2% to 79%. This tool projected the 5-year local recurrence rates would range from 1% to 57% for women who did not undergo radiotherapy. However, it projected local recurrences rates would range from 0% to 26% for women who did undergo radiotherapy.

The validation study included 487 women and the predicted 5-year mortality was 20%. The observed 5-year mortality was 16%. The predicted 5-year local recurrence rate was 3.9%. That was very close to the observed 5-year local recurrence rate of 3.1%. Overall, the outcome estimates projected by this new risk calculator tool were compatible with the observed estimates from real-world data.

The researchers are seeking to perfect the tool and hope that it may allow for clinicians to have more nuanced conversations with women over age 65 with early-stage breast cancer. “Future research collecting prospective data to validate our estimates is needed,” the authors concluded.

Reference

Wang S-Y, Mougalian S, Killelea B, et al. Development and validation of the “radiotherapy for older women” risk calculator. Poster presentation at: 2019 San Antonio Breast Cancer Symposium; December 10-14, 2019; San Antonio, TX. Abstract P5-07-08.