Elevated plasma Cobalamin Predicts a Poor Survival for Cancer Patients – a Population-based Cohort Study
Johan Frederik Berg Arendt1,2,*, Dóra Körmendiné Farkas2, Lars Pedersen2, Ebba Nexø1, Henrik Toft Sørensen2
1Department of Clinical Biochemistry, 2Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
Introduction: We have recently demonstrated that high plasma cobalamin (Cbl, vitamin B12) levels are associated with increased cancer risk among patients referred for Cbl measurement.
Objectives: To examine the survival among cancer patients with a plasma Cbl measurement prior to cancer diagnosis in a population-based cohort study.
Methods: We included all patients with a cancer diagnosis and Cbl levels of 200-600 (reference range, normal), 601-800 (high) and >800 pmol/L (very high) up to one year prior to diagnosis during 1998-2011 from the Danish Cancer Registry and Laboratory Information Systems Database in Northern Denmark. Patients on treatment with pharmacological doses of vitamin B12 were identified through the Aarhus University Prescription Database and were excluded. Data on comorbidity was obtained through the Danish National Registry of Patients and scored according to the Charlson Comorbidity Index. Cox proportional hazard regression was used to assess mortality risk ratios (MRR) and Kaplan-Meier curves were computed.
Results: We included 19,410 cancer patients. The survival rate was lower among patients with elevated Cbl levels than among those with normal levels (30-day survival, percentage: normal: 92.4%; high: 84.3%; very high: 77.8%). When adjusted for age, sex and comorbidity, 30-day mortality was elevated for patients with high and very high Cbl levels when compared to those with normal levels (MRR (95% confidence interval): high vs. normal: 2.2 (1.9-2.6); very high vs. normal: 3.5 (3.0-4.0)). The association between high Cbl levels and mortality remained robust when assessing 31-90 day and 91-365 day mortality, and showed a similar dose-response pattern.
Conclusion: Cancer patients with high Cbl levels have a higher mortality than cancer patients with normal Cbl levels. These findings may have a clinical impact on assessing prognosis of cancer patients.
Keywords: Biomarker, Cancer