The high prevalence of the B7H3 protein in numerous malignancies—including lung cancer, esophageal squamous cell carcinoma (ESCC), gastric cancer, pancreatic cancer, colorectal cancer, liver cancer, breast cancer, brain tumors, and prostate cancer—further underscores its potential clinical relevance, as the upregulation of B7H3 was found to be associated with tumor cell proliferation, metastasis, treatment resistance, and ultimately, poor prognosis. This evidence concerns the gene CD276 and breast cancer.