Prognostic impact of LY6K and CDCA1 expression for patients with esophageal squamous cell carcinoma

AIM: In the present study, we investigated the relationship between the expressions of two cancer testis antigens (CTA), LY6K (lymphocyte antigen 6 complex locus K) and CDCA1 (cell division cycle associated 1), in esophageal squamous cell carcinoma (ESCC) tumors and the long‐term outcomes of patients with ESCC to clarify the clinical significance of LY6K and CDCA1 expression in ESCC tumors. METHODS: A total of 175 patients with thoracic ESCC who had undergone a thoracic esophagectomy with three‐field lymphadenectomy without neoadjuvant therapy were retrospectively reviewed in this study. LY6K and CDCA1 expressions were evaluated in tumor tissues using immunohistochemical (IH) staining. RESULTS: Median patient age was 63 years; 159 patients (90.9%) were men. Ninety‐four patients (55.3%) were LY6K‐positive, and 85 patients (48.6%) were CDCA1‐positive. The LY6K‐positive group had a significantly worse overall survival (OS) than the LY6K‐negative group (P = 0.012), and the CDCA1‐positive group had a significantly worse OS than the CDCA1‐negative group (P = 0.010). A multivariate analysis suggested that pathological N stage, venous invasion, LK6Y‐positive and CDCA1‐positive were independent prognostic factors. The patients were classified into four groups according to the staining pattern combinations of the two CTA. The LY6K‐positive and CDCA1‐positive group was found to have a significantly poorer outcome than the other groups. CONCLUSION: ESCC patients with a combination of LY6K and CDCA1 expression in their tumor tissues had a worse prognosis than all the other ESCC patients and it was an independent factor associated with prognosis for patients with ESCC.