Molecular Subtypes in Locally Advanced Breast Cancer-Do They Have a Preferential Destination?

Abstract

Introduction: The patterns of relapse in breast cancer are very much driven by the intrinsic molecular subtypes, which have been studied mainly in early stage breast cancer and have prognostic implications. Aim: To explore the relationship between the different molecular subtypes and their predilection to a distinct distant metastatic site in locally advanced breast cancer. Materials and Methods: This was a retrospective review of the records of 70 women with a histopathological diagnosis of locally advanced breast cancer who received radiation therapy between January 2011 and September 2012. Results: In all the molecular subtypes, the most common site of metastasis is the most common first site of distant relapse as well. In luminal A it is the bone, in luminal B the liver and in triple negative and Human epidermal growth factor receptor 2 (HER2/neu) enriched it is the lung. But, the odds ratio was significant only among luminal A patients. There is no significant difference in disease free survival and overall survival between the molecular subtypes. But, luminal subtypes have a longer median survival (25 months) after the development of metastasis compared to non-luminal subtypes (7 months) with a p-value of 0.056. Conclusion: Different molecular subtypes of locally advanced breast cancer have a preferential distant destination and difference in survival post detection of metastasis. A wellstructured prospective study protocol with a longer follow up with a larger number of patients is required before tailor made surveillance protocols can be developed for the various molecular subtypes of locally advanced breast cancer.

Keywords

• breast neoplasms
• immunohistochemistry
• oestrogen
• progesterone
• receptors