Breast-conserving surgery with or without irradiation does not impact overall survival in early breast cancer: NEJM

The study showed that overall survival at ten years was almost similar in the two groups at 80.8% with no radiotherapy and 80.7% with radiotherapy.

There is limited level 1 evidence available on the omission of radiotherapy following breast-conserving surgery in older women (65 years or older) with hormone receptor-positive early breast cancer receiving adjuvant endocrine therapy.

To fill the knowledge gap, Ian H. Kunkler from the Institute of Genetics and Cancer at the University of Edinburgh in Edinburgh, United Kingdom, and colleagues performed a phase 3 randomized trial of the omission of irradiation.

The trial included women 65 years or older with hormone receptor–positive, node-negative, T1 or T2 primary breast cancer (with ≤3 cm tumours in the largest dimension) treated with breast-conserving surgery with adjuvant endocrine therapy and clear excision margin.

One thousand three hundred twenty-six patients were randomly allocated, 658 to whole-breast irradiation (40 to 50 Gy) or 668 to no irradiation. The median follow-up was 9.1 years. The researchers also assessed breast cancer–specific survival, regional recurrence, overall survival, and distant recurrence as the first event. Recurrence of local breast cancer was noted (primary endpoint).

The study led to the following findings:

• The cumulative incidence of local breast cancer recurrence within ten years was 9.5% in the no-radiotherapy group and 0.9% in the radiotherapy group (hazard ratio, 10.4).
• Although local recurrence was more common in the group that did not receive radiotherapy, the 10-year incidence of distant recurrence as the first event was not higher in the no-radiotherapy group than in the radiotherapy group, at 1.6% and 3.0%, respectively.
• Overall survival at ten years was almost identical in the two groups, at 80.8% with no radiotherapy and 80.7% with radiotherapy.
• The incidence of regional recurrence and breast cancer–specific survival also did not differ substantially between the two groups.

"Radiotherapy omission was linked with an increased incidence of local recurrence but had no negative effect on distant recurrence as the first event or overall survival in women 65 years of age or older with low-risk, hormone receptor–positive early breast cancer," the researchers concluded.

Reference:

The study, "Breast-Conserving Surgery with or without Irradiation in Early Breast Cancer," was published in the New England Journal of Medicine. DOI: 10.1056/NEJMoa2207586