- Compared with normal vitamin B12 level, elevated plasma B12 levels were associated with a higher 1-year cancer risk among persons seen in UK primary care.
- This association showed a non-linear dose-response pattern.
Why this matters
- Findings suggest that high plasma B12 levels can mark occult cancer.
- Study used data from The Health Improvement Network primary care database, United Kingdom to assess cancer risk among individuals with elevated B12 levels.
- Individuals were grouped based on plasma B12 levels (unit: pmol/L): reference range values of 150-600 and 3 groups with high plasma B12 levels: 601-800, 801-1000 and >1000
- Funding: Wellcome Trust and others.
- Among the 757,185 persons (female, 64%) included (median age, 55.8 years; median follow-up period, 2.8 years), 33,367 people were diagnosed with cancer during 2,874,059 years of follow-up.
- Compared to people with normal B12 levels, 1-year cancer risk was higher among people with elevated B12 levels.
- After adjustment for covariates, people with B12 >1000 pmol/L had an overall incidence rate ratio (IRR) of 2.42 (95% CI, 2.11-2.77) and an IRR within the first year of follow-up of 4.72 (95% CI, 3.99-5.58).
- Risks were particularly higher for liver cancer, pancreas cancer and myeloid malignancies among persons with elevated B12 levels.
- Study did not detect any use of over-the-counter B12 drugs.