The Effect of Vitamin D Levels on Breast Cancer-Related Lymphedema.

The purpose of this study was to compare plasma vitamin D levels in patients with breast cancer-related lymphedema (BCRL), breast cancer (BC) without lymphedema, and healthy populations, as well as relationship between clinical variables, lymphedema severity grading, and circulating vitamin D concentrations. This Case-control study was conducted between June 2017 and January 2025. The study comprised three cohorts: a case cohort of individuals diagnosed with breast cancer-related lymphedema (BCRL), a disease-matched control cohort of breast cancer (BC) patients without lymphedema (demographically aligned with the BCRL cohort by age and sex), and a reference cohort of healthy participants matched by age and sex. A total of 603 female individuals were included in the study with 201 individuals in each group. Post-hoc Games-Howell test analyses revealed a lower level of Vitamin D in the BCRL group compared to the BC and control groups (p<0.001, p<0.001) and lower levels in the BC group compared to the control group (p<0.001). Vitamin D deficiency was statistically significantly more frequent in BCRL group than in BC and control groups (p:<0.001) and the proportion of those with normal vitamin D were statistically significantly more frequent in control group than in BCRL and BC and control groups (p:<0.001). Analysis revealed a strong, significant negative correlation between circulating vitamin D concentrations and advancing lymphedema stage (r: -0.578, p:<0.001). These observations imply that hypovitaminosis D may contribute to breast cancer pathogenesis and modulate the risk of treatment-associated morbidities, particularly lymphedema progression. Therefore, it is recommended that individuals diagnosed with BC or at risk of lymphedema have their vitamin D levels checked regularly and take supplements if necessary.