RESUMO
BACKGROUND: Serum vitamin B₁₂ has been suggested as one of the cancer diagnostic markers and predictors for survival in cancer patients. In this study, we investigated the relationship between vitamin B₁₂ and tumor progression. METHODS: Solid tumor patients who had serum vitamin B₁₂ levels and radiologic test follow-up were included in the study. A total of 55 patients were included. Receiver operating characteristic analysis was performed to determine the cut-off value of vitamin B₁₂ for tumor progression. Kaplan-Meier method and Cox proportional hazard model for time to progression (TTP) were performed. Subgroup analysis was performed on patients with or without liver lesion (hepatocellular carcinoma and liver metastasis). RESULTS: The cut-off value of vitamin B₁₂ for tumor progression prediction was 691.4 pg/mL, the sensitivity was 57.1% and the specificity was 59.3%. Patients with vitamin B₁₂≥691.4 pg/mL had shorter median TTP (2.1 months vs. 3.4 months, P=0.011). In subgroup analysis of patients without liver lesion, median TTP was significantly shorter in patients with vitamin B₁₂≥691.4 pg/mL (1.6 months vs. 6.3 months, P=0.021), while there was no significant difference in TTP among the patients with liver lesion. Higher vitamin B₁₂ level (≥691.4 pg/mL) was an independent prognostic factor for tumor progression (adjusted hazard ratio 2.4, 95% confidence interval 1.2–4.8, P=0.019). CONCLUSIONS: Serum vitamin B₁₂ level can be used as a predictor of tumor progression in patients with solid tumors especially in patients without liver lesion. Additional large scale prospective studies are required to confirm this.