Tolerance and Oncological Outcomes of In-Field Reirradiation for Locally Recurrent Breast Cancer: A Long-Term Single-Center Experience

SIMPLE SUMMARY: Breast reirradiation could represent a valuable option for local recurrence of breast cancer in previously irradiated sites. We aimed to report on the efficacy and tolerability of this treatment in our institution. The results of this series combined with those available in the literature indicate that breast/chest wall reirradiation is feasible with good oncological results and low toxicity rates. ABSTRACT: Background: The management of cancer relapse in previously irradiated tissues is a challenging therapeutic issue. The aim of this work was to report our experience with breast reirradiation for locoregionally recurrent breast cancer. Methods: All patients who underwent breast or chest wall in-field reirradiation at the Institut Curie, Paris, France, between 2003 and 2019, were identified. Efficacy outcomes and physician-reported toxicities were retrospectively assessed. Results: A total of 21,372 patients underwent breast irradiation in our institution. Of these, 28 received a second course of radiotherapy to the homolateral breast/chest wall. A total of 18 (64%) patients were treated with a curative intent, and 10 (36%) were treated for palliative purposes. Only one acute and one late grade 3 adverse events were reported. One patient with major cardiovascular risk factors died of myocardial infarction 13 months after left breast reirradiation. The 2-year LRFS, OS, DSS, PFS and MFS were 59%, 79%, 82%, 46% and 75%, respectively, in the whole cohort. The 2-year LRFS (72% vs. 31%, p = 0.02), OS (94% vs. 50%, p < 0.01), DSS (94% vs. 56%, p < 0.01) and PFS (61% vs. 20%, p = 0.02) differed significantly between patients treated with curative or palliative intent but not the MFS (78% vs. 69%, p = 0.77). Among the patients, eight (29%) remained relapse-free 5 years after reirradiation. Conclusion: Breast/chest wall reirradiation appears to be feasible with good disease control, especially in patients treated with a curative intent, and presents acceptable toxicity rates.