Prediction of local failure for post-operative radiotherapy of resected brain metastases in breast cancer patients

Background: Single brain metastasis surgical resection remains an effective treatment for brain metastases. However, surgery alone associate with a high rate of local failure. The current guidelines recommend radiation to surgical cavity. The recommended dose for brain cavity after surgery remain to be define as most guidelines gives a very general suggestion about the dose and fractionation. The aim of this study was to determine what variable influence local control in this specific population. Methods: Retrospective analysis of 52 patients with breast cancer who undergo surgical resection to single brain metastases and who received post-operative radiotherapy between the years 2010–2022. All clinical and dosimetric variables were analyzed to evaluate their impact on local control. A predictive model for local control was calculated. Results: One year local control was 65.3%. HER-2 disease, size of initial tumor, time from initial surgery, total dose deliver and the type of lesion were all significant for local control. The most important variable was total dose deliver. A specific nomogram using 7 parameters for a prediction of local was computed. Conclusion: Brain metastases from breast cancer remain a life-threating condition. Surgery plays a critical role in the treatment of large symptomatic brain metastases for which Post-operative radiotherapy is essential. Choosing a regime of 5 fraction with a dose of 30Gy (BED4 > 70Gy) seem important for achieving local control and without increase toxicity.