Numerous reports confirm HVEM expression on tumor cells such as gastric cancer,, colorectal cancer, esophageal squamous cell carcinoma, hepatocellular carcinoma, breast cancer, melanoma, ovarian cancer, and clear cell renal cell carcinoma. An increased level of BTLA on TILs has been observed in melanoma, nonsmall cell lung cancer, hepatocellular carcinoma, as well as on some cancer cells., The role of the BTLA/HVEM complex in autoimmune diseases remains to be fully elucidated. This evidence concerns the gene BTLA and breast cancer.