Vitamin D and breast cancer recurrence in the Women’s Healthy Eating and Living (WHEL) Study

Abstract

There is a paucity of research evaluating the relation between vitamin D and recurrence of breast cancer after treatment. This study was designed to evaluate the associations between circulating concentrations of 25-hydroxyvitamin D [25(OH)D] and dietary, supplemental, and total intake of vitamin D and recurrent or new breast cancer events within the Women's Healthy Eating and Living (WHEL) Study. A prospective cohort study design (n = 3085) was used to evaluate the relation between dietary, supplemental, and total vitamin D intake and recurrent breast cancer, and a nested case-control study with 512 matched pairs was used for analysis of the association between 25(OH)D and breast cancer recurrence. No relation between 25(OH)D and breast cancer recurrence was observed. Compared with women with serum concentrations of 25(OH)D ≥ 30 ng/mL, adjusted odds ratios (95% CI) for breast cancer recurrence were 1.14 (0.57, 2.31) for those with concentrations < 10 ng/mL, 1.00 (0.68-1.48) for concentrations ≥ 10 and < 20 ng/mL, and 1.05 (0.76, 1.47) for concentrations ≥ 20 and < 30 ng/mL. No significant associations were observed when analyses were stratified by pre- and postmenopausal status or for local, regional, or distant recurrence or death. Vitamin D intake was not related to breast cancer recurrence overall, although for premenopausal women there was a significant inverse association between dietary vitamin D intake and recurrence (P for trend = 0.02). These results do not provide support for a relation between concentrations of 25(OH)D after treatment and the recurrence of breast cancer. This trial is registered at clinicaltrials.gov for the WHEL Study as NCT00003787.