LAUSR

Background Recent years have witnessed significant progress in the treatment of esophageal squamous-cell carcinoma (ESCC); however, the prognosis of ESCC is still unsatisfactory. Bio-markers are required to improve identification of high-risk populations and help management of ESCC. This study was to evaluate the role of serum CKAP4 in ESCC. Methods This longitudinal study recruited 207 ESCC patients and age-/sex-matched healthy controls. Circulating levels of CKAP4 were measured using ELISA kits, while the expression of CKAP4 in esophageal tissue was evaluated using Western blotting. Results Serum CKAP4 levels were higher in ESCC patients (380.2±171.3 pg/mL) than healthy controls (271.8±97.4 pg/mL; P<0.001). The area under the receiver-operating characteristic curve of serum CKAP4 levels to identify the presence of ESCC was 0.675 (95% CI 0.622–0.728; P<0.001). According to Youden’s index, the best cutoff value was 429.1 pg/mL (sensitivity 0.415 and specificity 0.995). Furthermore, after follow-up, multivariate analyses identified that pathological lymph node metastases were the poorest prognostic factor (HR 1.862, 95% CI 1.093–3.173; P=0.022), followed by serum CKAP4 (HR 1.437, 95% CI 1.025–2.014; P=0.035). When stratified by tertiles of serum CKAP4, subjects in the first tertile presented a mean survival time of 75.4 months (95% CI 68.0–81.9), which decreased significantly in the second tertile (73.8 months, 95% CI 61.4–86.3) and the third tertile (59.9 months, 95% CI 49.8–70.0, log-rank χ2=8.235; P=0.016). Conclusion These results suggested that serum CKAP4 could be a potential biomarker for clinical management of ESCC.