Effects of dietary zinc deficiency on esophageal squamous cell proliferation and the mechanisms involved

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 μg/dL) and a high Zn group (≤64 μg/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.

Esophageal ulcer related to zinc deficiency following a total gastrectomy

A 76-y-old Japanese man who had undergone gastrectomy 4.5 y earlier experienced 2 wk of sore throat, heartburn, and difficulty swallowing. Endoscopy showed deep, craterlike, longitudinal ulcers in the lower and middle esophagus. Immunohistochemistry and blood tests were negative for herpes simplex virus and cytomegalovirus infections. The patient reported no other symptoms affecting the gastrointestinal tract. Although his symptoms ameliorated after initial hospitalization and treatment, they re-emerged a few days after being discharged. Fifty-one days after being first admitted, he complained of glossalgia. The serum zinc level was found to be 38 µg/dL, which was below the reference range; the patient was diagnosed with zinc deficiency. After oral zinc administration, the patient was relieved of the symptoms, and his pain was alleviated. Upper gastrointestinal endoscopy after symptom relief showed improvement in the esophageal ulcers. He has continued taking zinc supplementations, and has not developed similar symptoms in the 5 y since being treated. To the best of our knowledge, this is the first case report of esophageal ulcers related to zinc deficiency.

Esophagus cancer and essential trace elements

Numerous epidemiological and laboratory studies on essential trace elements have reported protective associations in developing various cancer types, including esophagus cancer (EC). However, the results are not always consistent. Some essential trace elements could play a vital role in preventing esophagus cancer. Some showed no association with esophageal cancer risk, while others harmed individuals. This article reviews the association between the intake or supplementation of essential trace elements (especially zinc, copper, iron, and selenium) and the risk of esophageal cancer. Generally, zinc intake may decrease the risk of esophageal cancer (EC), especially in high esophageal squamous cell carcinoma (ESCC) prevalence regions. The association between copper supplementation and EC remains uncertain. Total iron consumption is thought to be associated with lower EC risk, while heme iron intake may be associated with higher EC risk. Selenium intake showed a protective effect against EC, especially for those individuals with a low baseline selenium level. This review also prospects the research direction of the association between EC and essential trace elements.