A study of microenvironment in invasive breast cancer-Tumor infiltrating lymphocytes and Stromal CD10 do not correlate with tumor grade and molecular subtypes

Background Breast cancer is the second most common cancer among women worldwide. Tumor microenvironment which constitutes fibroblasts, myofibroblasts, mesenchymal stem cells, adipocytes, tumor-infiltrating lymphocytes (TILs) and endothelial cells facilitates progression and development of cancer. CD10 which is expressed in the stromal cells is thought to be associated with the aggressiveness of breast cancer. The presence of TILs within the peritumoral stroma is an important biomarker that reflects antitumor immune response in breast cancer especially in HER-2 positive and Triple-negative breast cancers. Methods The study was undertaken with the objective to evaluate expression of Tumor Infiltrating lymphocytes and Stromal CD10 in Breast carcinoma. This was an analytical and cross-sectional study conducted from February 3, 2021, to February 2, 2022. Forty eight cases including core biopsies, excisional biopsies and mastectomies were evaluated for Stromal CD10 and 30 excisional biopsies were evaluated for TIL. Age, sex and laterality of the specimens were recorded. CD10 and TILs expression was determined in relation to histological grade and intrinsic molecular subtype. Results Forty eight cases of invasive breast carcinoma were studied. Total 16 cases were positive for stromal CD10 (33%). All the cases of grade 3 tumor were stromal CD10 positive. Triple negative cases showed highest frequency of cases with CD10 positivity (41%). TIL was evaluated only in 30 of the cases, as they were resection specimens, according to International TIL Working group 2014. Sixteen of these cases (53%) showed low TIL which was most common in grade 1 tumor followed by grade 2. TIL expression was high to intermediate most frequently in Triple-negative, HER-2 enriched and Luminal A subtypes constituting four cases each. Conclusion CD10 expression was detected in almost one third of cases of which expression was highest in Triple negative breast cancers and was 100% in grade 3 tumors. Low TIL was detected in about 53% of cases followed by intermediate TIL in 44% of cases. High to intermediate TIL was seen in Triple-negative breast cancers and HER-2 enriched tumors most frequently.