Patients with CUP in the favorable subgroup include women with papillary adenocarcinoma of the peritoneal cavity, women with adenocarcinoma involving the axillary lymph nodes, poorly differentiated carcinoma with midline distribution, squamous‐cell carcinoma involving cervical lymph nodes, men with blastic bone metastases and elevated prostate‐specific antigen (PSA), isolated inguinal adenopathy (squamous carcinoma), adenocarcinoma with a colon‐cancer profile (CK20+, CK7−, CDX2+) (adenocarcinoma), and patients with one small, potentially resectable tumor. This evidence concerns the gene CDX2 and adenocarcinoma.