PVR and breast cancer: Like our results in patients without oncogene mutations, CD155 overexpression has demonstrated deleterious prognostic significance in multiple other tumors, including pancreatic cancer, cholangiocarcinoma, sarcoma, melanoma, breast cancer, cervical cancer, head and neck squamous cell carcinoma (HNSCC), and osteosarcoma [3, 6, 18, 19], among which, it is significantly correlated with tumor stage, lymph node, and distant metastases [3], thus suggesting that CD155 may function as poor predictors of survival regardless of cancer type.