Elevated Serum Vitamin B12 Levels as a Potential Biomarker for Solid Tumors in Jordanian Patients: A Retrospective Case-Control Study.

Background: Vitamin B12 deficiency is classically associated with anemia and neurological dysfunction. However, recent studies suggest that elevated plasma vitamin B12 may indicate increased short-term cancer risk. This association remains largely unexplored in Middle Eastern populations, including Jordan, where cancer rates are rising and diagnosis often occurs at advanced stages due to limited screening. Objective: This study is aimed at investigating the association between serum vitamin B12 levels and the risk of colorectal, breast, and lung cancers in a Jordanian population, evaluating differences by cancer type and stage. Methods: A retrospective case-control study was conducted at King Abdullah University Hospital, Jordan, from January 2018 to December 2022. The study enrolled 260 patients diagnosed with colorectal, breast, or lung cancer and 260 matched healthy controls. Data collected included sociodemographic factors, clinical characteristics, and serum vitamin B12 levels. Results: Serum vitamin B12 levels were significantly higher in cancer patients compared with controls (579.23 ± 468.72 vs. 492.70 ± 174.36 pg/mL; Conclusion: Elevated serum vitamin B12 levels are significantly associated with solid cancers in Jordanian patients, particularly pronounced in lung cancer and advanced stages. These findings do not imply a causal relationship, but rather suggest that serum vitamin B12 may function as a potential biomarker for cancer detection and disease monitoring in resource-limited settings.