Predictors of durable no evidence of disease status in de novo metastatic inflammatory breast cancer patients treated with neoadjuvant chemotherapy and post-mastectomy radiation

Introduction: Definitive locoregional therapy including surgery and post-mastectomy radiation therapy (PMRT) has been offered to select IBC patients with de novo metastatic disease. Herein we examined predictive factors for progression-free survival after comprehensive PMRT radiation +/- locoregional treatment of metastatic sites. Methods: Charts of T4d, any N, M1 (de novo) patients who completed PMRT to ≥ 50 Gy from 2006-2011 were reviewed. Patients who received doses <50Gy to the primary site, received radiation at another facility or were treated pre-operatively were excluded. The remaining 36 patients formed the study cohort. Progression-free survival post-PMRT (PFSx) was assessed from the last day of radiation. Median dose to primary fields was 51 Gy. Boost doses ranged from 6-16 Gy. Results: Median age at diagnosis was 54 (range 33-70). Median follow up from primary irradiation completion was 31 months. Sixteen patients were Stage IV NED at last follow-up (IR 37-60 mo). Fifteen patients died of disease. Five patients experienced an in-field recurrence, three of which resulted from local recurrence at the medial edge of the field. Actuarial 5 year locoregional control (LRC) was 86%. Median PFSx was 20 months. All sites of gross disease were treated with radiation in 21/36 patients. Location of metastatic disease had no correlation with PFSx. Estrogen receptor (ER)- patients had shorter 5-yr actuarial PFSx (28% vs. 66%, P = 0.03) and 5 year actuarial OSx (37% vs 71%, P = 0.02). Nine patients (25%) developed a pathological complete response (pCR) after chemotherapy and with a median follow-up of 59 months, 7 remained without evidence of disease. Conclusions: Despite the poor prognosis associated with metastatic IBC, our data suggest that select patients may be appropriate candidates for locoregional therapy. Patients who achieve a pCR or those with ER + disease have a favorable PFSx. It remains unclear whether all gross disease needs to be addressed with locoregional therapy to provide benefit.