Abstract
Context: Breast carcinoma is a heterogenous disease with varied clinicopathological features andresponse to therapy. Molecular classification through gene studies helps in planning therapy but haseconomic constraints. Hence immunohistochemical subtyping of breast carcinomas has been used asa surrogate method. Criteria for this subtyping has undergone many modifications since it wasoriginally proposed. Objectives: To immunohistochemically subtype breast carcinomas based onSt.Gallen 2017 guidelines and analyse the differences in clinicopathological parameters like age,tumour size, histopathological grade and lymph node staging between the various subtypes.Materials and methods: The study was done retrospectively at a tertiary care health centre inSouth India on breast carcinoma patients from January 2017 to June 2020. Immunohistochemistrywas done with antibodies to the Estrogen receptor, Progesterone receptor, Human epidermal growthfactor receptor-2 (HER-2) and Ki-67. Immunohistochemical Subtypes were correlated withClinicopathological features. Results: The study had 107 cases. Hormone receptor (HR) positiveHER-2 negative was the most common subtype (55 cases, 51.4%). This subtype frequentlypresented without nodal metastasis (58.2%) and in >50 years of age (56.4%). Triple-negativesubtype frequently presented with grade III (69.2%), highest nodal metastasis stage (38.5%) andin < 50 years of age (69.2%). Conclusion: St.Gallen 2017 guidelines for immunohistochemicalsubtyping classified breast carcinomas into groups that differed significantly in theirclinicopathological features. Further studies on differences in treatment response and survival ratedifferences between these different subtypes are needed.
Highlights
Breast cancer is one of the leading causes of cancer-related mortality and morbidity in females
Hormone receptor (HR)-positive Human epidermal growth factor receptor-2 (HER-2) positive (81.8%) cases more often presented with grade II
Triple-negative, HR-positive HER-2 positive subtypes never presented with grade I (Table II)
Summary
Breast cancer is one of the leading causes of cancer-related mortality and morbidity in females. Due to these advancements in breast cancer therapy, the current focus is on identifying the optimal treatment strategy for individual breast cancer patients For this purpose, breast cancer patients can be classified into various subgroups based on their clinicopathological features and the ideal treatment for each subgroup is being studied [1]. The molecular subtype is one such predictive marker that has got prognostic significance as well [2] There are 5 molecular subtypes of breast cancer Luminal A, Luminal B, HER-2-neu enriched, Basallike and Normal breast-like These subtypes indicate the response to various forms of therapies, identifying the molecular subtype in each patient needs gene assays which are costly and needs advanced equipment as well. Such facilities might not be available routinely across all the centres, in the developing and underdeveloped countries
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