Patients with luminal A breast cancer and low-risk clinicopathological features may be able to safely forgo radiotherapy (RT) after breast-conserving surgery, according to research presented at the 2022 ASCO Annual Meeting.

Researchers found that patients who were at least 55 years of age and had T1N0, grade 1-2 luminal A breast cancer had a low risk of recurrence when they were treated with endocrine therapy alone for 5 years after breast-conserving surgery. 

This suggests these patients are candidates for omission of RT, according to Timothy Joseph Whelan, MD, of McMaster University in Ontario, Canada, who presented this research at the meeting.


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“We estimate that these results could apply to as many as 30,000 to 40,000 women per year who could avoid the morbidity, inconvenience, and cost of radiotherapy,” Dr Whelan said.

He and his colleagues conducted this prospective study (ClinicalTrials.gov Identifier: NCT01791829) in patients who were at least 55 years of age with invasive ductal T1N0, grade 1-2, luminal A breast cancer. The patients had undergone breast-conserving surgery (with margins of at least 1 mm) and sentinel lymph node biopsy, and they had received adjuvant endocrine therapy for at least 5 years. 

There were 500 patients included in the analysis. The mean age was 67 years, 66% had grade 1 tumors, and the mean tumor size was 1.1 cm. Four patients ultimately received RT, 8 did not receive endocrine therapy, and 21 withdrew from follow-up.

At 5 years, the local recurrence rate was 2.3%. There were 10 local recurrence events, and all were invasive. The rate of contralateral breast cancer was 1.9%, and the rate of any recurrence was 2.7%. 

The 5-year disease-free survival rate was 89.9%, and the 5-year overall survival rate was 97.2%. 

Reference

Whelan TJ, Smith S, Nielsen TO, et al. LUMINA: A prospective trial omitting radiotherapy (RT) following breast conserving surgery (BCS) in T1N0 luminal A breast cancer (BC). Presented at ASCO 2022; June 3-7, 2022. Abstract LBA501.