Potential thiamine deficiency and neurological symptoms in patients receiving chemotherapy for gastrointestinal cancer.

The aim of this retrospective study was to search for risk factors for neurological adverse events in gastrointestinal cancer patients receiving chemotherapy and analyze the relationship between thiamine serum levels and neurological adverse events.This is a single-center retrospective observational study. We enrolled patients who were diagnosed with gastrointestinal cancer at our hospital, for whom we measured the thiamine serum levels. We then performed a multivariate analysis (logistic regression) to identify risk factors for the neurological symptoms in our cohort. We then divided the patients into two groups, with and without neurological symptoms, based on their electronic medical records. By using the Mann-Whitney U-test, we performed a comparative analysis of the thiamine serum levels between the two groups. We also used descriptive statistics to examine the presence/absence of neurological symptoms or other potentially related clinical features in patients with decreased thiamine serum levels.The logistic regression analysis detected the decrease in thiamine serum levels as a statistically significant risk factor for neurological symptoms. The analysis of the relationship between the presence/absence of neurological symptoms and thiamine serum levels showed that the thiamine serum levels were significantly lower in the group presenting neurological symptoms. Descriptive statistics showed that all the patients with decreased thiamine serum levels had either cognitive decline, attention decline, or depression symptoms, and most of them were receiving the 5-fluorouracil anticancer drug and showing decreased serum albumin levels. We also observed a slight decrease in serum sodium, vitamin B12, and folate levels.When neurological symptoms occur in patients receiving chemotherapy for gastrointestinal cancer, the measurement of thiamine serum levels may become a standard reference for treatment indication.