Breast Conservation in Women with Autoimmune Disease: The Role of Active Autoimmune Disease and Hypofractionation on Acute and Late Toxicity in a Case-Controlled Series.

PURPOSE: Autoimmune connective tissue disease (CTD) has historically represented a relative contraindication to breast conservation (BC) among patients with early-stage breast cancer. Controversy exists regarding the use of hypofractionated radiation therapy (RT) among patients with CTDs. We evaluated acute and late toxicity in patients with breast cancer and CTD treated with BC.

METHODS AND MATERIALS: Of 1983 patients treated with BC from 2012 to 2016, we identified 91 patients with an autoimmune disease (AD). Each patient was matched to a control without AD based on age, RT field, and fractionation. RT toxicity and clinician-rated cosmesis were compared between cases and controls. Overall survival, disease-free survival, and local recurrence-free survival were estimated using the Kaplan-Meier method.

RESULTS: The median follow-up was 49.9 months for cases and 53.0 months for controls, and 67% of cases and controls were treated with hypofractionated RT. There was no difference in grade 2/3 acute toxicity between cases and controls (26.4% vs. 16.5%, respectively; P = .148). There was a significantly higher rate of grade 2/3 late toxicity among cases (25.8% vs 12.1% among controls; P = .049). Active AD at the time of RT increased the rate of grade 2/3 late toxicity compared with controls (41.7% in cases vs. 11.4% in controls; P = .018). Among patients treated with hypofractionated RT, there was no difference in acute or late grade 2/3 toxicity between cases and controls (acute: 13.1% in cases vs. 11.5% in controls [P > 0.9]; late: 11.9% in cases vs. 13.1% in controls [P > 0.9]). The rates of good/excellent clinician-rated cosmesis were similar between groups (92.9% in cases vs. 98.9% in controls; P = .142).

CONCLUSIONS: In the largest matched case-control study of patients with CTD treated with conventional and hypofractionated RT, we demonstrate low rates of radiation toxicity, with good to excellent clinician-rated cosmesis. There was increased late toxicity in cases, especially in patients with active AD at time of RT. There was no increase in acute or late toxicity in the patients treated with hypofractionation.