A prospective observational study of zinc deficiency symptoms during first-line chemotherapy for gastric and colorectal cancer

Abstract

Background Zinc deficiency during long-term courses of chemotherapy and its related symptoms, including skin rash, taste disorder, and oral mucositis, has not been sufficiently investigated. Methods This prospective observational study enrolled patients with gastric and colorectal cancer who underwent standard first-line chemotherapy. According to the Practice Guideline for Zinc Deficiency, zinc deficiency is defined as a serum level of < 60 μg/dL. Serum zinc levels were measured before and after (1, 3, and 6 months) chemotherapy, and symptoms were assessed using the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events version 1.0. Repeated measures were analyzed using a generalized linear mixed model. Results Of the 61 enrolled patients, we analyzed 48 patients who underwent standard first-line chemotherapy with fluoropyrimidine plus oxaliplatin. Zinc deficiency was observed in 18 patients (38 %) before chemotherapy. The least-square means of serum zinc levels significantly decreased at 3 and 6 months of chemotherapy in 30 patients without zinc deficiency at the start of chemotherapy (both p < 0.01) but not in 18 patients with zinc deficiency at the start. Changes in serum zinc levels during chemotherapy were negatively correlated with taste changes, rash, and itching (all p < 0.04) in patients without zinc deficiency before treatment initiation. Conclusions Serum zinc levels decreased during chemotherapy in zinc-non-deficient patients at the start of chemotherapy and were correlated with taste changes, skin rash, and itching. Therefore, it is necessary to investigate whether zinc supplementation can improve these symptoms.