Examining Radiotherapy Assumptions in Breast Cancer Care

Researchers sought to evaluate whether radiotherapy would benefit patients aged 70 years or older with hormone-negative invasive breast cancer who had undergone breast-conserving surgery. Results were presented at the Miami Breast Cancer Conference in late February.

The randomized CALGB 9343 study found that radiotherapy did not improve overall survival (OS) for patients of similar age and tumor size with estrogen receptor (ER)-positive disease, says lead author Emily C. Daugherty, of the Department of Radiation Oncology at Upsala Cancer Center. She and her colleagues, wondered whether the same findings would hold true for patients with ER-negative disease, who have fewer treatment options.

To explore the question, the researchers queried SEER registries for patients surgically treated for breast cancer between 1998 and 2011, and created two cohorts: one for the 3685 patients treated with radiation and another for the 1493 individuals who did not receive radiation.

The outcomes between the two groups differed sharply. The five-year median OS for patients who received radiotherapy was 139 months (81 percent) versus 88 months (61.7 percent) for those who did not. Additionally, the five-year cancer-specific survival rates were 93.1 percent with radiotherapy versus 85 percent without radiotherapy.

The differences are “pretty large and significant,” says Daugherty. She said a limitation of the study was that the data are retrospective and were drawn from registries. However, the differences in survival rates—particularly cancer-specific survival—are large enough that physicians should consider the potential benefit in this setting.

“It warrants a good discussion with the patient and seeing what their goals of care are,” Daugherty says.