Comparison of disease free survival in breast cancer molecular subtypes.

Background: Breast cancer management depends on molecular subtypes. The aim was to compare disease-free survival (DFS) among the different subgroups. Overall survival (OS) is a secondary endpoint. Methods: This cross-sectional study was done on breast cancer women that were treated in our center, from 2009 to 2015. Breast cancer molecular subtypes were determined based on clinicopathological criteria recommended by St Gallen and include; luminal A, luminal B Her- 2-neu positive, luminal B Her-2-neu negative, Her-2 enriched and triple negative. Patients with metastasis at diagnosis or those without follow-up were excluded. Patients were followed-up from 12 to 132 months. Cox regression analysis was used for analogy of DFS and OS between the subgroups. Results: Out of three hundred patients, 221 were enrolled with median age of 47 years old (26 to 83). Luminal B, Her-2 negative was the most common subgroup with 83 patients (35.5%). Five and 10 years PFS were 95% and 81% for luminal A, were 95.5% and 92% for luminal B Her-2 positive, were 92% and 91% for luminal B Her-2 negative, were both 84% for triple negative and were 76% and 74% for Her-2 enriched subgroups, respectively. With multivariate analysis, the stage of tumor (HR=5.9 CI=1.06-32.69) and triple negative subgroup (HR=5.2 CI=1.33-20.31) were independent factors for recurrence. Conclusion: Based on the results of this study, the triple-negative breast cancer and possibly Her-2 enriched subgroup have a shorter DFS than luminal breast cancers. Also, the stage of tumor is an independent factor for recurrence.