Key clinical point: Patients with microinvasive breast cancer (BC) had a significantly higher risk for local recurrence and comparable rates of distant recurrence and death compared with patients with T1a-2 BC.
Major finding: Although the 10-year local recurrence rate was significantly higher in patients with microinvasive vs T1a-2 BC (hazard ratio 3.73; P < .001), the 10-year distant recurrence risk ( P = .36) and overall survival rates ( P = .14) were similar between both patient populations.
Study details : Findings are from the Canadian Hypofractionation trial including 1234 patients with T1-2 N0 invasive BC who were randomly assigned to receive hypofractionated or conventional fractionated whole breast irradiation, of which 3% of patients had microinvasive BC.
Disclosures: Dr Whelan declared receiving support from the Canada Research Chair in Breast Cancer Research and research funding unrelated to this study.
Source: Goldberg M et al. Long-term outcomes and effects of hypofractionated radiotherapy in microinvasive breast cancer: Analysis from a randomized trial. Breast. 2023;68:189-193 (Feb 9). Doi: 10.1016/j.breast.2023.02.005