(Ivanhoe Newswire) -- A new report shows adding radiation therapy to a treatment regimen already consisting of chemotherapy and radical mastectomy leads to better survival outcomes among women with high-risk breast cancer. And it had few long-term side effects.

Between 1979 and 1986, 318 patients were randomly assigned to receive radiation therapy or no radiation at all. In a 20-year follow-up, researchers from McGill University Health Center in Montreal found the chemotherapy/radiation combination, compared with chemotherapy alone, was associated with vast improvements for the patients. These included a 32-percent reduction in breast cancer mortality and a 27-percent reduction in overall mortality. Additionally, long-term toxic effects, including cardiac deaths, were acceptable for both groups of patients.

Researchers say, "Our results, and those from other groups, confirm that in situations where residual disease remains, adjuvant chemotherapy alone in high-risk breast cancer patients is suboptimal and that the addition of locoregional radiation therapy is important to achieve the highest cure rate."

Other researchers add, "Because uncertainties continue about the effectiveness of locoregional radiation therapy after mastectomy in moderate-risk patients, we strongly urge that a randomized controlled trial be mounted to resolve these uncertainties."