Radiotherapy may be omitted in many breast cancer patients

The prospective cohort study LUMINA found that women ≥55 years with T1N0, G1-2 luminal A breast cancer who underwent breast conserving surgery (BCS) had a very low rate of local recurrence (LR) if they were treated exclusively with endocrine therapy and not with radiotherapy. These results indicate that the morbidity and costs of radiotherapy could be avoided in a substantial proportion of women with breast cancer.

Although the risk of local recurrence after BCS is reduced by approximately 67% with adjuvant radiotherapy, this treatment may be omitted in very low-risk patients. Prof. Timothy Whelan (McMaster University, Canada) presented results from the LUMINA study (NCT01791829) which aimed to determine whether identifying luminal A subtype breast cancer combined with clinical pathological factors could identify very-low risk patients in whom radiotherapy could be omitted after BCS [1]. For this purpose, a prospective analysis was made from 500 women ≥55 years with T1N0, G1-2 luminal A-type ductal BC who only followed endocrine therapy, and not radiotherapy, after BCS. Additionally, only patients who had ≤13.25% on a Ki67-test were included in the analysis. The primary endpoint was met if the LR rate was <5% after 5 years.

The LR rate was 2.3% after 5 years of follow-up (90% CI 1.3‒3.8). Moreover, the rates of contralateral breast cancer (1.9%) and any recurrence (2.7%) were low. The disease-free survival after 5 years was 89.9%, with 47 reported events, of which 23 were second primary non-breast cancer. The overall survival after 5 years was 97.2%, but only 1 out of 13 deaths was breast cancer related.

“This study showed that the risk for LR after BCS is very low in a substantial proportion of patients with breast cancer,” stated Dr Whelan. “We estimate that radiotherapy could be omitted in approximately 30,000 to 40,000 of the 300,000 patients who are newly diagnosed with invasive breast cancer in North America each year, avoiding the morbidity, inconvenience, and costs of this therapy.”

1. Whelan T, et al. LUMINA: A prospective trial omitting radiotherapy (RT) following breast conserving surgery (BCS) in T1N0 luminal A breast cancer (BC). LBA501, ASCO 2022 Annual Meeting, 3–7 June, Chicago, IL, USA.

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Posted on 9 June, 2022