Peritumoural Mast Cell Density in Invasive Breast Carcinoma: Possible Antitumourigenic Effect with Potential Role for Immunotherapy

Abstract

Introduction: The interaction of cancer cells and the host within the tumour microenvironment plays a major role in determining the outcome of cancers. Mast cells are part of the innate immune system that interact with tumour cells and known to have pro-tumourigenic and antitumourigenic action through their mediators. Their role in the outcome of invasive breast cancer is still not clear with studies showing both a beneficial role as well as a role in tumour progression. Aim: To assess Mast Cell Density (MCD) in tissues of invasive carcinoma of breast and compare with clinicopathological parameters to infer their biological significance. Materials and Methods: The study was a retrospective cross-sectional study carried out at the Department of Pathology, SRM Medical College Hospital & Research Centre, SRMIST, Kattankulathur, Chennai, India on 51 cases of invasive carcinoma of breast received between January 2011 and July 2013 and the study conducted between August to November 2013. Clinical parameters and histopathological findings were recorded. Mast cells were clearly demonstrated in tissue using Toluidine Blue stain at pH 2.3. The MCD within primary malignant breast tumour tissue (mastectomy specimens, n=51) was assessed using an eyepiece grid and expressed as no. of cells/per sq. mm. Statistical analysis of all parameters was performed using SPSS software (v 17.0) to analyse association of MCD with clinicopathological parameters. Results: The MCD was significantly higher in malignant breast tissue compared to non neoplastic breast tissue (p<0.0001). No significant difference in MCD was observed between tumour size groups (T1, T2, and T3) (p=0.6967). No statistically significant difference in MCD was observed between the four histological types observed (p=0.892). The majority of the tumours were of Grade 2 category (n=37), followed by Grade 3 (n=11) and Grade 1 (n=3). No significant difference in MCD was observed between the three histological grades (p=0.785). The MCD was significantly higher in patients without lymph node metastasis compared to the group with lymph node metastasis (p=0.0023*). The MCD in invasive carcinoma of breast, post-chemotherapy group was significantly higher than that in invasive carcinoma of breast pre-chemotherapy group (p=0.0064). Conclusion: The current study shows significantly increased MCD at the periphery of the carcinoma breast tissue in patients without lymph node metastasis compared to those with lymph node metastasis. Hence, a potential antitumourigenic and beneficial role of mast cells in invasive primary breast carcinoma could be inferred and may serve as one of the prognostic indicators for patient stratification for various treatment options including immunotherapy