Breast cancer is a multifaceted disease with diverse clinical, pathologic and molecular features which led to different prognostic outcomes. We aim to examine factors that influence survival outcome among ER+ HER2- patients from a single institution.
Data of patients diagnosed between January 1, 2005 and December 1, 2011 was extracted from the University Malaya Medical Centre Breast Cancer Registry. Kaplan-Meier method was used to estimate overall survival. Overall survival was defined from date of diagnosis to date of death from any cause. Log rank tests and Cox hazards regression model were used to compare survival and identify prognostics factors. Stage 4 patients were excluded from univariate and multivariate analysis.
In 951 patients with ER + /HER2- breast cancer, median age at diagnosis was 54 years (range, 24-89) with 50.7% Chinese followed by Malays (35.1%) and Indians (13.3%). 94.5% of breast cancer patients received hormone therapy while 91% had surgery. Slightly over half of the cohort (53.2%) present with T2 tumor size (2-5cm). 5 years survival probability according to stage; stage 1, 95.4% (95% CI, 91.7-97.4), stage 2, 88.6% (95% CI, 84.7-91.6), stage 3, 74.9% (95% CI, 68.3-80.4) and stage 4, 27.5% (95% CI, 16.1-40.1). 7.4% were diagnosed with stage 4 with median survival of 2.4 years (95% CI, 1.9-3.1). In univariate analysis; increasing age (p < 0.001), tumor size (p < 0.001) and number of lymph nodes (p < 0.001), significantly led to poorer survival while those receiving hormone therapy (HR: 0.50, 95% CI: 0.27-0.93) and surgery (HR: 0.11, 95% CI: 0.05-0.23) had greater survival benefits. Ethnicity and grade was not associated with survival outcome. Age, tumor size and number of lymph nodes remain significant as independent survival predictor in the multivariate model.
In this cohort, we found increasing age, tumor size and number of lymph node was associated with poorer survival outcome among ER + /HER2- breast cancer patients. Ethnic disparities in survival outcome were not apparent in this molecular subset.
Clinical trial identification
Y.Y. Lee: employee of Pfizer Malaysia Sdn Bhd. All other authors have declared no conflicts of interest.