CEACAM5 and esophageal squamous cell carcinoma: In this study, owing to the availability of large-scale, real-world clinical EMR data, we 1) had relatively adequate statistical power to assess targeted markers both pre- and post-operatively (post-hoc test: >95% power for SCC and CEA); 2) and we were able to adjust up to eleven conventional confounding factors which ensured the establishment of an independent association between serum tumor markers and prognosis in ESCC patients.