A Laboratory-based Exploratory Study of Tumour-associated Macrophages and their Subpopulation M1 and M2 by Immunohistochemistry in Primary Breast Carcinoma

Introduction: Breast carcinoma is one of the common causes of mortality in women. The macrophage is the primary immune cell present in the tumour microenvironment. They are, therefore, also called Tumour-Associated Macrophages (TAMs). CD68 has a proinflammatory and anti-tumour response. CD (cluster of differentiation)163 has an anti-inflammatory response. The collection of TAMs correlates with adverse clinical outcomes. Tumour microenvironment targeting helps in reducing tumour burden and improving prognosis.

Aim: To study the density of expression of TAMs in primary breast carcinoma and study the association of TAMs with stage and grade of primary breast carcinoma.

Materials and Methods: This was a laboratory-based exploratory study conducted in the Kolar district of Karnataka, from December 2018 to May 2020 and data of 55 primary breast carcinoma cases were included. Cases with metastatic tumours from other sites, recurrent lesions, and patients subjected to chemotherapy and radiotherapy were excluded. Haematoxylin and Eosin (H&E) slides were reviewed. Immunostaining for CD68 and CD163 was performed. The cases were distributed into low and high groups based on cut-off points according to the median. Statistical Package for Social Sciences (SPSS) version 22.0 was used for statistical analysis and a p-value of <0.05 was considered statistically significant.

Results: Out of the total 55 cases, the maximum number of cases were between 50-59 years and maximum patients lump sized between 2-5 cm. The study demonstrated that the density of CD68 macrophages in the peritumoural area increased as the pathological stage increased (p-value 0.037) and the density of CD68 macrophages in the intratumoural area decreased as the tumour grade increased (p-value 0.023). Cancer tissue showed higher CD163 TAMs density than those in normal tissues, but the association with pathological stage, grade, and lymph node metastasis was not significant (p-value >0.05).

Conclusion: The CD68 targeted therapy can be used to treat breast carcinoma as it inhibits the tumourigenic factors at the interface between tumour and stroma.