Abstract
IntroductionVitamin D has been postulated to be involved in cancer prognosis. Thus far, only two studies reported on its association with recurrence and survival after breast cancer diagnosis yielding inconsistent results. Therefore, the aim of our study was to assess the effect of post-diagnostic serum 25-hydroxyvitamin D [25(OH)D] concentrations on overall survival and distant disease-free survival.MethodsWe conducted a prospective cohort study in Germany including 1,295 incident postmenopausal breast cancer patients aged 50-74 years. Patients were diagnosed between 2002 and 2005 and median follow-up was 5.8 years. Cox proportional hazards models were stratified by age at diagnosis and season of blood collection and adjusted for other prognostic factors. Fractional polynomials were used to assess the true dose-response relation for 25(OH)D.ResultsLower concentrations of 25(OH)D were linearly associated with higher risk of death (hazard ratio (HR) = 1.08 per 10 nmol/L decrement; 95% confidence interval (CI), 1.00 to 1.17) and significantly higher risk of distant recurrence (HR = 1.14 per 10 nmol/L decrement; 95%CI, 1.05 to 1.24). Compared with the highest tertile (ā„ 55 nmol/L), patients within the lowest tertile (< 35 nmol/L) of 25(OH)D had a HR for overall survival of 1.55 (95%CI, 1.00 to 2.39) and a HR for distant disease-free survival of 2.09 (95%CI, 1.29 to 3.41). In addition, the association with overall survival was found to be statistically significant only for 25(OH)D levels of blood samples collected before start of chemotherapy but not for those of samples taken after start of chemotherapy (P for interaction = 0.06).ConclusionsIn conclusion, lower serum 25(OH)D concentrations may be associated with poorer overall survival and distant disease-free survival in postmenopausal breast cancer patients.
Highlights
Vitamin D has been postulated to be involved in cancer prognosis
Participants with lower 25(OH)D levels were diagnosed at a somewhat older age, had a shorter time interval between diagnosis and blood collection, a higher body mass index (BMI) at time of recruitment, and less leisure time physical activity since age 50 years compared with participants with higher 25(OH)D levels
25(OH)D, 25-hydroxyvitamin D; CI, confidence interval; CT, chemotherapy; Hazard ratios (HR), hazard ratio. a Stratified by age at diagnosis and season, adjusted for tumor size, nodal status, metastases, tumor grade, estrogen/progesterone receptor status, diabetes, mode of detection b Calculated by using serum 25(OH)D as a continuous variable. c No chemotherapy or blood collection before start chemotherapy. d Blood collection after start chemotherapy
Summary
Only two studies reported on its association with recurrence and survival after breast cancer diagnosis yielding inconsistent results. Low vitamin D levels have been inconsistently associated with increased breast cancer risk [1]. As 1,25(OH)2D is homeostatically tightly regulated, 25(OH)D is a better It is currently unclear whether vitamin D affects breast cancer survival, some circumstantial evidence exists. Lower serum 25(OH)D levels have been associated with more advanced stages of breast cancer. An observational study among Caucasian women showed that serum levels of 25(OH)D were lower in patients with locally advanced or metastatic breast cancer than in those with early-stage disease [10]. In a multi-ethnic cohort of breast cancer survivors, women with localized or regional breast cancer had lower serum 25(OH)D levels than those with in situ disease [11]
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