Pathologic Complete Response and Oncologic Outcomes in Locally Advanced Breast Cancers Treated With Neoadjuvant Radiation Therapy: An Australian Perspective.

PURPOSE: To assess the degree of pathologic complete response (pCR), postoperative surgical complication rates, and oncological outcomes in women with locally advanced breast cancer or high-risk breast cancers treated with neoadjuvant radiation therapy (NART). METHODS AND MATERIALS: This retrospective, multi-institutional review involved 138 clinically staged patients with 140 breast cancers treated with NART between January 2014 and February 2021. Treatments involved sequential neoadjuvant chemotherapy and NART, followed by mastectomy with or without axillary surgery and immediate autologous breast reconstruction. Descriptive statistics were used to assess patient and disease features, treatment regimens, pathologic response, and factors affecting postoperative complications. Kaplan-Meier curves were performed to assess locoregional recurrence-free, distant metastasis-free, and overall survival outcomes. RESULTS: Median age was 47 years (interquartile range, 42-52). The median follow-up was 35.2 months (interquartile range, 17.1-46.5). pCR was achieved in 36.4% (as defined by Chevallier classification) or 42.1% (as defined by Miller-Payne scores) of patients. Greater pCR rates were achieved for HER2+ (73.8%-85.7%) and triple-negative phenotypes (47.6%-57.1%). There were 21 grade 3 surgical complications including 10 grade 3B breast events and 8 grade 3B donor-site events, where surgical reintervention was required. At 3-years' follow-up, the locoregional recurrence-free survival was 98.1%, distant metastasis-free survival was 83.6%, and overall survival was 95.3%%. CONCLUSIONS: NART is feasible to facilitate a single-stage mastectomy and immediate autologous breast reconstruction. This study demonstrated comparable rates of postoperative complication to standard of care, and high rates of pCR, which translates to high rates of locoregional control, distant metastasis-free survival, and overall survival.

Neoadjuvant radiotherapy for locally advanced and high-risk breast cancer.

INTRODUCTION: Neoadjuvant radiotherapy (NART) as part of a multi-modality approach for locally advanced breast cancer (LABC) requires further investigation. Importantly, this approach may allow for a single-staged surgical procedure, with mastectomy and immediate autologous reconstruction. Multiple other potential benefits of NART include improved pathological downstaging of breast disease, reduced overall treatment time, elimination of time period with breast tissue deficit and improved patient satisfaction. METHODS: This is a retrospective multi-institutional review of patients with LABC and high-risk breast disease undergoing NART. Eligible patients sequentially underwent neoadjuvant chemotherapy (NACT) with or without HER2-targeted therapy, NART, followed by mastectomy with immediate autologous breast reconstruction (BR) 4- to 6 weeks post-completion of radiotherapy. Patient and tumour characteristics were analysed using descriptive statistics. Surgical complications were assessed using the Clavien-Dindo Classification (Ann Surg 2004; 240: 205). RESULTS: From 3/2013 to 9/2019, 153 patients were treated with NART. The median age was 47 years (IQR 42-52), with median body mass index of 27. Eighteen patients experienced Grade 3 acute surgical complications. This included 13 Grade 3B breast-site events and 9 Grade 3B donor-site events, where further surgical intervention was required for management of wound infection, wound dehiscence, flap or mastectomy skin necrosis, haematoma and internal mammary venous anastomotic thrombosis. No autologous flap loss was observed. CONCLUSION: Neoadjuvant radiotherapy facilitates a single-stage surgical procedure with mastectomy and immediate autologous BR, eliminating the delay to reconstructive surgery and thus shortening a woman's breast cancer journey. The findings of this review support the use of NART, with comparable rates of surgical complications to standard sequencing.