Soluble B7H3 level in breast cancer and its relationship with clinicopathological variables and T cell infiltration.

Aim of the study: Although early diagnosis of breast cancer (BC) is often associated with a good prognosis, there is currently no biomarker with high sensitivity serving this purpose. B7H3, a recently identified member of the B7 family, appears to inhibit antitumor immunity. We investigated the soluble B7H3 (sB7H3) level in BC and its relationship with clinicopathological variables and stromal tumor-infiltrating lymphocytes (sTILs). Material and methods: The study, which was designed as a cross-sectional trial between January 2020 and September 2021, included 93 BC patients, 20 patients with benign breast disease (BBD) and 14 healthy volunteers as the control group. Serum sB7H3 levels were measured using the ELISA (enzyme-linked immunosorbent assay) method and sTILs were measured by immunohistochemistry using Tru-cut biopsy materials. Results: sB7H3 levels in BC patients were significantly higher than those in patients with BBD and healthy volunteers. Receiver operating characteristic curve analysis results showed that sB7H3 level may be a potential biomarker for distinguishing patients with BC from those with BBD (AUC: 0.807; sensitivity: 0.786; specificity: 0.706) and from healthy volunteers (AUC: 0.731; sensitivity: 0.700; specificity: 0.692). Conclusions: To the best of our knowledge, the present study is the first to investigate the relationship between sB7H3 and disease parameters in BC. We found that sB7H3 may be a clinically practical and meaningful biomarker in differentiating BC from BBD. In order to evaluate the relationship of B7H3 with clinical variables in BC, and especially with sTILs, tissue-based studies with higher numbers of patients are needed.