Association between preoperative serum zinc level and prognosis in patients with advanced esophageal cancer in the neoadjuvant treatment era

Background: Zinc (Zn), an essential trace element, has an adverse influence on the prognosis of several cancers. However, the association between the preoperative serum Zn level and outcomes in patients with advanced esophageal cancer in the current neoadjuvant treatment era remains unclear. Methods: This study involved 185 patients with esophageal cancer who underwent R0 surgery after neoadjuvant chemotherapy from August 2017 to February 2021. We retrospectively investigated the relationship between the preoperative serum Zn level and the patients' outcomes. Results: The patients were divided into a low Zn group (<64 mu g/dL) and a high Zn group (<= 64 mu g/dL) according to the mean preoperative serum Zn level. Low Zn had significantly worse overall survival (OS) (2-year OS rate: 76.2% vs. 83.3% in low vs. high Zn; p = 0.044). A low Zn in pathological non-responders (Grade <= 1a) was significantly associated with a shorter 2-year recurrence-free survival (RFS) rate (39.6% vs. 64.1% in low vs. high Zn; p = 0.032). The multivariate analysis identified low BMI and Zn level among preoperative nutritional status indices as an independent risk factor for worse RFS in non-responders. Compared with responders, pathological non-responders comprised significantly more males and a performance status of >= 1, and there was no difference in Zn level according to pathological response. Conclusion: A preoperative low Zn level had a negative impact on early recurrence in esophageal cancer patients who underwent neoadjuvant chemotherapy. This suggests the need to administer Zn supplementation to patients with esophageal cancer who have preoperative Zn deficiency.