Peritumoural and Tumour Infiltrating Lymphocytes in Breast Carcinoma and their Relation with Tumour Grade, Lymphovascular Emboli and Nodal Metastasis: A Cross-sectional Study

Introduction: Inflammatory cell infiltrate in tumours may be involved in immunosurveillance or tumourigenesis. Tumour Infiltrating Lymphocytes (TILs; within the tumour) and peritumoural lymphocytes (at the invasive margin) are associated with improved prognosis and response to therapy.

Aim: To estimate the presence of peritumoural lymphocytes and TILs in breast carcinoma, identify their subsets by Immunohistochemistry (IHC) and assess the relationship between them and tumour grade, lymphovascular emboli and axillary lymph node metastasis.

Materials and Methods: This was a cross-sectional study with a sample size of 75 done in the Department of Pathology, Government Medical College, Kozhikode, Kerala, India from November 2017 to April 2019 with the approval of Institutional Ethics Committee. The demographic data of the patients were collected and histopathological assessment of tumour type, grade, lymphovascular emboli, nodal metastasis and lymphocytic infiltrate was done on Haematoxylin and Eosin (H&E) stained sections. Immunohistochemical evaluation was performed using antibodies against Cluster of Differentiation 4 (CD4) and CD8 and cells were scored separately in the stromal and peritumoural areas. The results were analysed by Analysis of Variance (ANOVA) and Chi-square test. Association between the immune infiltrate and histopathological variables were assessed separately in stromal and peritumoural compartments. Association between the score obtained on H&E and subpopulation score obtained on IHC was also analysed in both the compartments.

Results: Total of 75 subjects were included and the mean age was 52.31 years with a standard deviation of 9.774 years. The degree of stromal TIL infiltrate ranged from 10% to 95%, with a mean of 48.47%. High grade peritumoural infiltrate was seen in 66.67% (50 out of 75 cases). The stromal TILs were significantly higher in higher grade tumours and tumours without nodal metastasis. The peritumoural lymphocytes were also significantly higher in high grade tumours. The scoring of the immune infiltrate on H&E sections and subpopulation score on IHC showed significant association for both stromal and peritumoural compartments.

Conclusion: Stromal TILs and peritumoural lymphocytes were significantly higher in high grade tumours. Stromal TILs were also significantly higher in tumours without axillary lymph node metastasis. No significant association was found between the lymphocytic infiltrate and lymphovascular emboli. The immune infiltrate within breast carcinoma has association with tumour grade and lymph node metastasis.