The AMAZONA Project: Retrospective Cohort Study Describing Breast Cancer Patients' Characteristics and Survival in Brazil

Abstract

Background: Breast cancer is the most common cancer in women in Brazil and worldwide. There is large variation in survival among patients and molecular subtypes are important prognostic factors. However, most of the data comes from developed countries such as the United States and in Europe. Aim: Our goal was to describe breast cancer patients' demographic and pathologic characteristics, as well as their survival according to estimated molecular subtypes, assessed by common immunohistochemistry stains. Methods: AMAZONA study is a retrospective cohort conducted from June 2008 to January 2009 including women of at least 18 years old, with histologically proven breast cancer diagnosed in the period between 1 January 2001 and 31 December 2001 and between 1 January 2006 and 31 December. Estimated molecular subtypes by local immunohistochemical stains were luminal A, luminal B, HER-2 positive and triple-negative. Data were obtained from medical records and public databases. Kaplan-Meier method was used for data description and log-rank test for comparison between the subgroups. Results: 2296 patients were included in this analysis. Mean age was 54 years. Most subjects included came from hospitals located in the southeast region of the country, treated in the public health system and had stage II invasive ductal carcinoma of breast. Regarding subtype, 71.3% had hormonal receptor positive disease, 15.7% were HER-2 positive and 21.1% had triple-negative breast cancer. Overall survival (OS) was significantly different among molecular subtypes and was independent of pathologic stage for stages II and III patients. For stage III patients 5-years OS for luminal A subtype was 75.8% and for triple-negative was 56.1% ( P .0002). Conclusion: Classification of breast cancer patients in predicted molecular subtypes using immunohistochemistry is currently available in most underdeveloped countries and is a useful prognostic tool that goes beyond clinical or pathologic stage.