Patterns Of Care And Comparison Of Outcomes Between Patients With Inflammatory Breast Cancer Who Were Treated With Standard Versus Dose-Escalated Adjuvant Radiation Therapy

There have been conflicting studies on whether there is a benefit to dose escalation for inflammatory breast cancer. In this study we analyzed the patterns of care and survival outcomes of patients with inflammatory breast cancer treated with standard versus dose-escalated adjuvant radiation therapy. The National Cancer Database was explored to identify patients diagnosed with primary inflammatory breast cancer from 2004-2014 and treated with neoadjuvant chemotherapy followed by mastectomy and adjuvant radiation. Standard radiation dose was defined as 6000cGy. Dose-escalated radiation therapy was defined as between 6600-7000cGy. Median age and pathologic nodal stage were compared between groups using the Mann-Whitney’s test. Frequency distributions between categorical variables were compared using the Chi-square test. Both groups were stratified by pathologic nodal status (ypN0 versus ypN+) and radiation dose, and overall survival (OS) data was obtained and compared via the log-rank test. Univariate and multivariate Cox proportional hazards regression models were performed to assess the impact of covariates on survival for each group. There were 1227 patients included in this study, of which 1057 patients (86.1%) were treated with standard dose adjuvant radiation therapy and 170 (13.9%) were treated with dose-escalated adjuvant radiation therapy. The median follow-up for living patients was 57.1 months. The 5-year OS for patients treated with standard dose radiation therapy was 63.3% compared to 57.9% for those treated with adjuvant dose-escalated radiation therapy (p=0.24). On subgroup analysis by pathologic nodal status, for patients with pathologic node positive disease (ypN+), the 5-year overall survival with adjuvant standard dose radiation was 59% versus 53.4% for those treated with dose-escalated adjuvant radiation therapy (p=0.40). For patients with pathologic node negative disease (ypN0), the 5-year OS was 74% for patients treated with standard dose radiation therapy and 77.8% for patients treated with dose-escalated radiation therapy (p=0.40). On multivariate analysis there remained no OS benefit associated with dose escalation (HR 0.916, 95% CI 0.70-1.19, p=0.51). Standard dose adjuvant radiation therapy is the predominant practice pattern seen in the treatment of inflammatory breast cancer among hospitals within the U.S. There was no overall survival benefit noted in those who were treated with dose escalation.