Success Of Preoperative Radiotherapy In Inflammatory Breast Cancer With Inadequate Response To Taxane-Based Chemotherapies

Inflammatory breast cancer (IBC) has a poor prognosis, with a locally-aggressive phenotype and high predilection for metastasis, requiring multi-modality therapy. Taxane-based chemotherapy (TBC) has improved outcomes and the ability to pursue mastectomy, which is critical to durable disease control. Disease with inadequate response to TBC suggests particularly aggressive biology. The role of preoperative radiotherapy (RT) in improving the likelihood of successful resection with minimal toxicity and negative margins in this patient group is not well delineated. We evaluated the impact of preoperative RT in patients with an inadequate response to neoadjuvant TBC. Between 2012-2018, we identified IBC patients who were evaluated by breast surgeons after neoadjuvant chemotherapy, not deemed appropriate for resection at completion of TBC, and referred for preoperative RT. Patient, disease, and pre-surgical treatment characteristics were collected. Descriptive statistical analysis of surgical outcomes with attention to conversion to resectability, surgical margins, treatment response, complication rates, on loco-regional recurrence were evaluated. Nine patients with T4d staged disease meeting the criteria were identified. Median age at diagnosis was 56 (29 – 74), with 100% of patients having node-positive disease, 22% with a focal metastatic lesion, and 78% with estrogen receptor-positive tumors. All patients were initiated on neoadjuvant chemotherapy, receiving an average of 3 (range 2 – 4) chemotherapy regimens due to inadequate response for mastectomy. Multi-disciplinary decisions were made to proceed with preoperative RT. Radiation was delivered to the breast, regional nodal basins and any extension of skin disease noted at the time of CT simulation, with bolus for each fraction to a dose of 5100cGy in 150cGy fractions given twice daily (78% of patients) or once daily RT with concurrent capecitabine. All completed the prescribed radiation and eight of the nine patients successfully converted to resectable disease, of which 100% achieved R0 mastectomy. Mastectomy specimens revealed pathologic complete response (pCR) in 38% of primary diseases, 25% nodal pCR, and one patient with a pCR in both the primary and nodes. Median residual primary disease was 1cm (0 – 11). A grade 1 postoperative wound complication was noted in one patient which resolved with conservative management. 100% of postoperative patients received adjuvant therapies. With a median follow up of 18 months (1 – 72), there was a single low cervical regional recurrence 4 years after surgery. Preoperative RT should be considered in IBC patients with suboptimal response to neoadjuvant chemotherapy and may result in successful surgery with negative margins and minimal toxicity.