HealthDay News — Women aged 65 years who receive hormone treatment after surgical removal of hormone receptor–positive axillary node-negative breast cancer may choose to skip whole breast radiotherapy, according to results of a phase 3 study presented at the 2013 San Antonio Breast Cancer Symposium.
Overall survival was similar in patients who did and did not undergo radiotherapy after surgery — 94.2% vs. 93.8% (38 vs. 49 deaths; P=0.37), Ian Kunkler, MB, BChir, from the University of Edinburgh in the United Kingdom, and colleagues reported.
“We have identified a subgroup of older patients at sufficiently low risk of recurrence for whom omission of postoperative radiotherapy after breast-conserving surgery and adjuvant endocrine therapy is a reasonable option,” Kunkler said.
Although more than 50% of patients with early breast cancer are aged 65 years or older, evidence is lacking on the role of postoperative radiotherapy after breast-conserving surgery.
So Kunkler and colleagues enrolled 1,326 women 65 years and older in the Postoperative Radiotherapy in Minimum-Risk Elderly (PRIME) study between April 2003 and December 2009. All patients had low-grade (T1-2), hormone receptor-positive, metastasis-negative and axillary node-negative breast cancer with clear excision margins (at least 1 mm) and had received hormone treatment.
The women were randomly assigned to either receive (N=658) or not receive radiotherapy (N=668). Mean patient age was similar between groups (70.9 and 71.1 years in the radiotherapy and no radiotherapy arm, respectively).
The primary end point was ipsilateral breast tumor recurrence; secondary end points were regional recurrence, contralateral breast cancer, distant metastases, and overall survival (OS).
After a median follow up of 4.8 years, the researchers found that ipsilateral breast tumor recurrence (IBTR) at five years was significantly higher for women who did not receive radiotherapy (2.7 vs. 0.6 percent; hazard ratio, 4.3).
Among estrogen-receptor rich patients, the difference was 3.2% without radiotherapy versus 0.8% with radiotherapy (P = 0.003).
A total of 26 patients in the arm without radiotherapy had local recurrence, for a 5-year actuarial rate of 4.1%. In the radiotherapy arm, five patients had local recurrence, for a rate of 1.1% (95% CI: 0.1%-2.0%; P<0.001). On multivariate analysis, the hazard ratio for local recurrence was 5.08 (95% CI: 1.95-13.24; P<0.001).
Breast cancer-free survival was significantly higher for women receiving radiotherapy (98.5% versus 96.4%). However, there were no significant differences between the two groups in overall survival, regional recurrence, contralateral breast cancer, or distant metastases.
“What this study shows is that for every 100 women (from our selected population) treated with radiotherapy, one will have a recurrence anyway, four will have a recurrence prevented, but 95 will have had unnecessary treatment,” Kunkler said.
“Once a patient has had radiotherapy, they are unable to have it again on the same breast. Had these women not had radiotherapy, they would have been able to have minor surgery and radiotherapy following a recurrence,” he added. “Besides, radiotherapy carries its own health risks, particularly in the elderly, as well as the inconvenience of travel for daily treatment for 3 or 4 weeks.”
Radiotherapy should not be omitted in patients with estrogen-receptor poor, high-grade tumors, where risk of recurrence is relatively high.