Radiation Therapy is not recommended for older women with hormone receptor-positive early breast cancer who have had breast-conserving surgery. This is due to limited evidence at level 1.
METHOD
A phase 3 randomized trial was conducted to determine whether the omission of radiation is possible. The trial population consisted of women aged 65 and older with hormone receptor-positive, node-negative T1 or T2 breast cancer. Patients had tumors greater than 3 cm in size. They were treated with breast-conserving surgery that leaves clear margins. Adjuvant endocrine treatment was also used. Randomly, patients were assigned to receive either whole-breast radiation (40-50 Gy) or none. Local breast cancer recurrence was the primary endpoint. The primary endpoint was local breast cancer recurrence.
RESULTS
There were 1326 women enrolled. 658 received whole-breast radiation and 668 were not. The median follow-up was 9.1 years. The cumulative incidence rate of local breast cancer recurrence over a period of 10 years was 9.5% (95% confidence interval [CI], 6,8 to 12,3) in the no radiotherapy group, and 0.9% (95%CI, 0,1 to 1.7 in the radiotherapy groups (hazard ratio: 10.4; 95%CI, 4.1-26.1; P0.001). Although local recurrence was higher in those who did not receive radiotherapy treatment, distant recurrence rates over 10 years were not as high in either group. They were 1.6% (95% confidence interval [CI], 0.4 to 2.8) and 3.0% (95%CI, 1.5 to 4.5), respectively.
The overall survival rate at 10 years was nearly identical between the two groups at 80.8% (95% confidence interval, 77.2 to 84.1) with no radiotherapy and at 80.7% (95% confidence interval, 76.9 - 84.3) radiotherapy. There was no significant difference in the incidence of breast cancer-specific mortality and regional recurrence between the two groups.