Breast-Conserving Surgery with or without Irradiation in Early Breast Cancer

Author(s): Ian H. Kunkler, M.B., B.Chir., Linda J. Williams, Ph.D., Wilma J.L. Jack, M.B., Ch.B., David A. Cameron, M.D., and J. Michael Dixon, M.D.
Source: N Engl J Med 2023; 388:585-594 DOI: 10.1056/NEJMoa2207586
Maem Hussein MD

Dr. Maen Hussein's Thoughts

Another radiation trial for older women. Radiation reduces local recurrence but not distant metastasis or overall survival. Again, hope one of our FCS radiation oncologists will share their thoughts in the comment section below.

BACKGROUND

Limited level 1 evidence is available on the omission of radiotherapy after breast-conserving surgery in older women with hormone receptor–positive early breast cancer receiving adjuvant endocrine therapy.

METHODS

We performed a phase 3 randomized trial of the omission of irradiation; the trial population included women 65 years of age or older who had hormone receptor–positive, node-negative, T1 or T2 primary breast cancer (with tumors ≤3 cm in the largest dimension) treated with breast-conserving surgery with clear excision margins and adjuvant endocrine therapy. Patients were randomly assigned to receive whole-breast irradiation (40 to 50 Gy) or no irradiation. The primary end point was local breast cancer recurrence. Regional recurrence, breast cancer–specific survival, distant recurrence as the first event, and overall survival were also assessed.

RESULTS

A total of 1326 women were enrolled; 658 were randomly assigned to receive whole-breast irradiation and 668 to receive no irradiation. The median follow-up was 9.1 years. The cumulative incidence of local breast cancer recurrence within 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 group (hazard ratio, 10.4; 95% CI, 4.1 to 26.1; P<0.001). 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% (95% CI, 0.4 to 2.8) and 3.0% (95% CI, 1.4 to 4.5), respectively. Overall survival at 10 years was almost identical in the two groups, at 80.8% (95% CI, 77.2 to 84.3) with no radiotherapy and 80.7% (95% CI, 76.9 to 84.3) with radiotherapy. The incidence of regional recurrence and breast cancer–specific survival also did not differ substantially between the two groups.

CONCLUSIONS

Omission of radiotherapy was associated with an increased incidence of local recurrence but had no detrimental effect on distant recurrence as the first event or overall survival among women 65 years of age or older with low-risk, hormone receptor–positive early breast cancer. (Funded by the Chief Scientist Office of the Scottish Government and the Breast Cancer Institute, Western General Hospital, Edinburgh; ISRCTN number, ISRCTN95889329. opens in new tab.)

Author Affiliations

Prof. Kunkler can be contacted at i.kunkler@ed.ac.uk or at the Institute of Genetics and Cancer, University of Edinburgh, Crewe Rd., Edinburgh, EH4 2XR, United Kingdom. A list of the collaborators in the PRIME II trial is provided in the Supplementary Appendix, available at NEJM.org.

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