We investigated the relationship between TMB and microsatellite instability (MSI) and TM4SF18 expression in different tumor types expressed, and the results showed that the expression of TM4SF18 in breast invasive carcinoma, lymphoid neoplasm diffuse large B‐cell lymphoma, HNSC, KICH, LUSC, ovarian serous cystadenocarcinoma, and STAD was significantly negatively correlated with MSI (P < 0.05). Here, TM4SF18 is linked to invasive breast carcinoma.