Trends in Molecular Classification of Breast Carcinoma in a Tertiary Health Care Centre: A 5 year Retrospective Study

ABSTRACT

Introduction: ER, PR and HER2 are the most important factors for predicting prognosis and response to treatment. In the present study we retrospectively  measured the frequency of estrogen receptor (ER), progesterone receptor (PR), and Her 2 Neu positivity in breast cancer patients during a span of 5 years and classified them into luminal A (estrogen receptor/progesterone receptor [ER/PR]-positive and human epidermal growth factor receptor-2 [HER2]-negative), luminal B (ER/PR- positive and HER2-positive), HER2 (ER/PR-negative and HER2-positive), and triple negative (ER/PR- and HER2-negative) molecular subtypes. In this study we have also tried to correlate various molecular subtypes of breast cancer with age distribution, histological grade, lymph node status and distant metastasis. Methodology: We conducted a 5-year retrospective study on 547 patients. Clinical data including the age, sex, lymphnode status along with histological type and, grade of the tumour were recorded and the cases were subjected for immunohistochemical evaluation of HER-2/neu, ER, PR receptor status. Results: The results showed that HER2 neu was the most predominant immunomarker, while ER and PR was almost half of it. Among the molecular sub typing HER 2 type was the most prevalent constituting 53% of the cases, followed by almost triple negative and luminal A subtype with 20% cases each. Luminal B was least frequent with 9% of the cases. An inverse relationship exists between expression of her 2 neu and ER/PR. Conclusion: Our study concluded that molecular subtyping of breast carcinoma is an important part of complete histopathology report, in terms of prognosis, recurrence and treatment. A shift in occurrence of breast malignancies towards younger age leads to increased Her-2 neu expression.