Abstract P3-10-07: Lymph node status and survival in inflammatory breast cancer

Abstract

Abstract Objectives: Positive lymph node status in breast cancer is known to be associated with poor outcomes when compared with node-negative disease, but the effect of lymph node status on outcomes in inflammatory breast cancer (IBC) has not been evaluated. This study was designed to investigate the association between lymph-node status and overall survival (OS) in individuals with inflammatory breast cancer using prospective data from the Surveillance, Epidemiology, and End Results (SEER) database. Methods: We identified 750 patients in the April 2012 edition of the SEER 17 registry who had non-metastatic IBC diagnosed from 1973–2008. Patients were included only if they met a stringent definition of IBC (ICD-O-2 morphology code 8503) and their pathologic nodal status was known. Patients who did not receive mastectomy as part of their local therapy were excluded, to minimize the likelihood of inadvertently including patients with metastatic disease at or shortly after diagnosis. A total of 711 patients were deemed evaluable for analysis (145 node-negative, 566 node-positive). Survival analysis was performed using the Kaplan–Meier method. Cox proportional hazard regression was performed to evaluate univariate and multivariate associations between treatment and OS. Information regarding receipt of systemic therapy and human epidermal growth factor receptor 2 (HER2) status was not available in this version of the SEER database. Results: Positive lymph node status was associated with a significant decrease in OS (p = 0.01) when compared with node negative status. In lymph node-positive patients, ER or PR positivity was associated with better OS than ER or PR negativity (adjusted HR 0.56 (p = 0.005) for ER+ vs. ER−, and adjusted HR 0.55 (p = 0.009) for PR+vs. PR−). In patients with positive lymph nodes, the combination of surgery and radiation therapy improved overall survival when compared with surgery alone (adjusted HR 0.56, p = 0.003). In node-negative patients, the combination of surgery and radiation therapy was not clearly superior to surgery alone, possibly due to the rarity of node-negative IBC (adjusted HR 0.53, 95% CI 0.23–1.19, p = 0.13). Conclusions: Our findings provide a better understanding of the characteristics of inflammatory breast cancer, and creates the opportunity for future studies to evaluate the prognostic significance and treatment implications of lymph node status in inflammatory breast cancer. Our study is limited by lack of knowledge of use of systemic therapy, the HER2 status for each patient, and information regarding locoregional recurrence. However, institutions participating in the SEER registry are likely to follow guidelines set forth by the National Comprehensive Cancer Network, recommending induction chemotherapy followed by surgery followed by radiation for IBC. Nearly 80% of the IBC patients included in this study had nodal metastasis, reflecting the inherently aggressive biology of this disease. Further studies are required to characterize the biology of IBC and guide the optimal treatment of this disease. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P3-10-07.