Is Functional Vitamin B12 Deficiency a Risk Factor for the Development of Chemotherapy-Induced Peripheral Neuropathy...

Chemotherapy-induced peripheral neuropathy (CIPN) is a common, significant, debilitating symptom of anticancer treatment, and continues to plague patients and medical fraternity. This study aimed to explore the associations between CIPN and functional vitamin B12 deficiency, as well as other predictors including nutritional and non-nutritional factors among cancer patients.

A prospective study design was conducted to achieve the study objectives, utilizing a non-probability purposive sampling technique. A consecutive case series of 64 adults (≥ 18 years) newly diagnosed cancer patients of various sites, registered and scheduled to receive the first cycle of chemotherapy were recruited from the Oncology Department of European Gaza Hospital (EGH). At two different points of time, at the baseline before the initiation of the first cycle of chemotherapy (pre) and after the completion of the chemotherapy regimen (post), vitamin B12 status was evaluated using serum vitamin B12 and it is related metabolites methylmalonic acid (MMA) and homocysteine (Hcy), and CIPN was evaluated using patient neurotoxicity questionnaire (PNQ).

The results reported the presence of a functional vitamin B12 deficiency, such that there is a drastic reduction in serum vitamin B12 levels (355.0(IQR 115.0) to 219.0(IQR 177.0) pg/mL, P < 0.001), accompanied by a significant increase in it is related metabolites MMA (3.9(IQR 3.0) to 49.7(IQR 32.0) ng/mL, P < 0.001) and Hcy (3.90(IQR 0.85) to 12.60(IQR 7.05) ng/mL, P < 0.001) after the completion of  chemotherapy regimen. Increases in serum MMA levels significantly predicted increases in PNQ scores (b = 0.02, R2 = 0.30, P = 0.001).

Functional vitamin B12 deficiency as defined by increased MMA levels is a distinct risk factor in the development of CIPN in cancer patients undergoing chemotherapy. Further studies are required to evaluate the impact of vitamin B12 therapy in the management and/or prevention of CIPN.