Vitamin D status is associated with tumoral activity marker, but not with musculoskeletal health, in early breast cancer

Summary: Background & Aims: Breast cancer (BC) is the most commonly diagnosed cancer and the leading cause of cancer-related death among women. Despite increasing interest in vitamin D and musculoskeletal health, the relationship between vitamin D status, musculoskeletal outcomes, and tumoral activity prior to the initiation of clinical treatment remains unclear. This study aimed to investigate the association between vitamin D status, musculoskeletal health, and lactate dehydrogenase in women with early-stage BC. Methods: This cross-sectional study analyzed 53 BC women prior to clinical treatment. Participants were categorized into two groups based on vitamin D status: sufficiency (≥30ng/mL) and insufficiency (20–29ng/mL). Assessments included body composition (DXA), handgrip strength (HGS), and physical function tests. Serum 25-hydroxyvitamin D [25(OH)D] and LDH levels were also measured. Associations between [25(OH)D], LDH, and musculoskeletal outcomes were evaluated using correlation analyses and multivariate generalized linear models adjusted for menopausal status, with additional adjustment for body mass index (BMI) in sensitivity analyses. Results: Most participants (54.7%) had vitamin D insufficiency. No significant differences were observed between vitamin D status groups in factors potentially influencing vitamin D levels. Serum 25(OH)D was inversely associated with LDH levels. In multivariate analysis adjusted for menopausal status, higher 25(OH)D levels were independently associated with lower LDH concentrations, and non-menopausal women presented significantly lower LDH levels compared with menopausal women. Probable sarcopenia was identified in 15.1% of participants and confirmed sarcopenia in 5.7%, with no differences in musculoskeletal parameters or sarcopenia traits across groups. Conclusions: Vitamin D status was not associated with musculoskeletal health in women with early BC. However, higher [25(OH)D] were independently associated with lower LDH, a known prognostic marker in BC, highlighting the potential relevance of vitamin D status in tumor metabolic activity prior to treatment initiation and supporting further longitudinal studies.