O1-11-1 - Prognostic Power of Molecular Subtypes in Inflammatory Breast Cancer: a Multicentric Study

Abstract

Background: Inflammatory breast cancer (IBC) represents up to 15% of all breast cancer in North Africa. However, this form is poorly characterized and its subtypes defined by hormonal receptor (HR) and HER2 status have not been well studied yet. In this study, we compared pathological complete response (pCR) rates, progression free survival (PFS) and overall survival (OS) by HR/HER2 subtype in IBC North African population.Methods: We retrospectively reviewed data of 65 IBC patients from Morocco, Egypt and Tunisia. All patients had received neoadjuvant sequential chemotherapy. Patients included had available information on estrogen receptor (ER, progesterone receptor (PR, HER2 status and Mib1 score. Kaplan Meier method was used to estimate median PFS and OS durations from the time of first cycle of chemotherapy. The Cox proportional hazards regression model was used to determine the effect of molecular subtypes on PFS and OS.Results: The mean patient age was 46.5 years. The histological grade distributions were 55.9% for grade II tumors, 40.7% for grade III. The immune-histochemical study showed that 1.6% of the tumors were classified as luminal A, 69% as luminal B, 9.5% as Her2 overexpressing and 19% as triple negative. The overall pCR rate was 4.5%, with the HR-positive/HER2-positive subtype showing the highest rate (16.66%). The median PFS was 651 days and median OS was 780 days. In the multivariate analysis, there was no significant statistic difference between all the molecular subtype groups regarding PFS and OS.Conclusions: Molecular subtypes had limited predictive and prognostic power in our IBC population. All molecular subtypes of IBC had a poor prognosis. To improve outcome, further specific therapeutic strategies have to be developed in the neoadjuvant setting.