(ChemotherapyAdvisor) – A nomogram developed to predict the likelihood of long-term breast preservation with and without radiation therapy (RT) among older women with breast cancer can help individualize clinical decision making by estimating predicted benefit from RT, investigators at The University of Texas MD Anderson Cancer Center, Houston, TX, and The University of Chicago, Chicago, IL, reported in the Journal of Clinical Oncology online June 25.

“Guidelines based on recent clinical trials have suggested that RT may be omitted in selected patients with favorable disease. However, it is not known whether this recommendation should extend to other older women,” the investigators wrote.

They identified 16,092 women aged 66 to 79 years treated with conservative surgery between 1992 and 2002 using Surveillance, Epidemiology, and End Results–Medicare data. Claims were used to identify receipt of RT and subsequent mastectomy. The nomogram was developed to predict 5- and 10-year mastectomy-free survival, given associated risk factors.

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At a median 7.2 years follow-up, overall 5-year mastectomy-free survival rate was 98.1% and 10-year, 95.4%. “In multivariate analysis, age, race, tumor size, estrogen receptor status, and receipt of RT were predictive of time to mastectomy and were incorporated into the nomogram,” they noted. Nodal status, which also had a significant interaction with RT, was also included.

The “clinically useful tool” predicts 5- and 10-year mastectomy-free survival “using readily available clinicopathologic factors,” the authors wrote.

“Given that indications for RT remain unclear and continue to be debated for older patients, this nomogram will be useful to patients and physicians when evaluating adjuvant treatment options. Future prospective studies are needed to more accurately determine the risk of recurrence for different subgroups of older patients with early breast cancer and further refine indications for RT in this population,” they concluded.

Link to abstract: