Elevated Serum Vitamin B 12 Levels as a Prognostic Factor for Survival Time in Metastatic Cancer Patients: A Retrospective Study.

Background: Serum vitamin B-12 levels have been proposed as one of the survival prediction factors, although no survival analysis in metastatic cancer patients has been conducted yet. This study examined whether serum vitamin B-12 levels could be a prognostic factor in metastatic cancer patients. Methods: Data from a retrospective chart review were used to perform Kaplan-Meier and multivariate analyses of the Cox proportional hazards. Subgroup analysis was performed on patients without a liver lesion (hepatocellular carcinoma or liver metastasis). Results: A total of 523 patients were included. The median survival time was 1.8 months (mo) in the high B-12 group (> 911 pg/mL) and 5.1 mo in the normal B-12 group (211-911 pg/mL) (p < 0.001). In patients without a liver lesion, the median survival times were 2.1 and 6.1 mo in the high and normal B-12 groups, respectively (p < 0.001). Multivariate analysis revealed that serum vitamin B-12 level was an independent prognostic factor for overall survival (hazard ratio [HR]: 1.62; 95% confidence interval [CI]: 1.34-1.96, p < 0.001). Conclusion: Serum vitamin B-12 level can be used to predict survival time in metastatic cancer patients. Further large-scale cohort studies are required to confirm these findings.