Analysis of TIMER databases showed that STAT3 expression level was negatively related to tumor purity in nine cancer types significantly, including BLCA, cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), COAD, esophageal carcinoma (ESCA), KICH, KIRC, LIHC, PRAD, and rectum adenocarcinoma (READ). Here, STAT3 is linked to rectum adenocarcinoma.