Cancer treatments, toxicities and their effects on lifestyle, may impact levels of vitamin D. The aim of this study was to determine serum 25-hydroxyvitamin D3 (25(OH)D 3 ) levels before, directly after and 6 months after chemotherapy in breast cancer patients (n = 95), and a comparison group of women (n = 52) not diagnosed with cancer. Changes in 25(OH)D 3 levels over time were compared using linear mixed models adjusted for age and season of blood sampling. Before start of chemotherapy, 25(OH)D 3 levels were lower in patients (estimated marginal mean 55.8 nmol/L, 95% confidence interval (95%CI) 51.2–60.4) compared to the comparison group (67.2 nmol/L, 95%CI 61.1–73.3, P = 0.003). Directly after chemotherapy, 25(OH)D 3 levels were slightly decreased (–5.1 nmol/L, 95%CI –10.7–0.5, P = 0.082), but ended up higher 6 months after chemotherapy (10.9 nmol/L, 95%CI 5.5–16.4, P < 0.001) compared to pre-chemotherapy values. In women without cancer, 25(OH)D 3 levels remained stable throughout the study. Use of dietary supplements did not explain recovery of 25(OH)D 3 levels after chemotherapy. We reported lower 25(OH)D 3 levels in breast cancer patients, which decreased during chemotherapy, but recovered to levels observed in women without cancer within 6 months after chemotherapy. Suboptimal 25(OH)D 3 levels in the majority of the participants highlight the relevance of monitoring in this vulnerable population.
All Science Journal Classification (ASJC) codes
- Medicine (miscellaneous)
- Nutrition and Dietetics
- Cancer Research