Cytokeratin 7 is a predictive marker for survival in patients with esophageal squamous cell carcinoma.

Patients diagnosed with stage II and III esophageal squamous cell carcinoma (ESCC) have variable prognosis. This group would benefit greatly from the discovery of prognostic markers that are capable of identifying individuals for whom adjuvant treatment would be advantageous. The aim of this study was to investigate the impact of immunohistochemically detected cytokeratin 7 (CK7) expression on disease-free survival, overall survival (OS), or therapeutic outcome in patients with ESCC. Immunohistochemical analysis of CK7 was performed on 225 surgically resected specimens of stage 0-III ESCC. In total, 20 (9%) of 225 ESCC cases were positive for CK7. In stage 0-III ESCC patients, CK7 expression was statistically significantly associated with OS, independent of clinical covariates, including tumor, node, metastasis system stage. In stage II and III ESCC patients (n = 124), CK7 expression was significantly associated with poorer OS (P = 0.0377). Furthermore, in stage II and III ESCC patients who did not receive adjuvant chemotherapy (n = 73), CK7 expression was significantly associated with poorer OS (P = 0.0003). CK7 expression was not associated with therapeutic outcome in patients with stage II and III ESCC who received adjuvant chemotherapy. In patients with CK7-positive ESCC (n = 16), receipt of adjuvant chemotherapy tended to be beneficial for patients with stage II and III ESCC (P = 0.0654). Immunohistochemical analysis of CK7 will help to identify high-risk patients.