Breast cancer risk markedly lower with serum 25-hydroxyvitamin D concentrations ≥60 vs <20 ng/ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort

PLoS One. 2018 Jun 15;13(6):e0199265. doi: 10.1371/journal.pone.0199265. eCollection 2018.

Abstract

Background: While numerous epidemiologic studies have found an association between higher serum 25-hydroxyvitamin D [25(OH)D] concentrations and lower breast cancer risk, few have assessed this association for concentrations >40 ng/ml.

Objective: To investigate the relationship between 25(OH)D concentration and breast cancer risk across a broad range of 25(OH)D concentrations among women aged 55 years and older.

Methods: Analyses used pooled data from two randomized clinical trials (N = 1129, N = 2196) and a prospective cohort (N = 1713) to examine a broad range of 25(OH)D concentrations. The outcome was diagnosis of breast cancer during the observation periods (median: 4.0 years). Three analyses were conducted: 1) Incidence rates were compared according to 25(OH)D concentration from <20 to ≥60 ng/ml (<50 to ≥150 nmol/L), 2) Kaplan-Meier plots were developed and 3) multivariate Cox regression was used to examine the association between 25(OH)D and breast cancer risk using multiple 25(OH)D measurements.

Results: Within the pooled cohort (N = 5038), 77 women were diagnosed with breast cancer (age-adjusted incidence: 512 cases per 100,000 person-years). Results were similar for the three analyses. First, comparing incidence rates, there was an 82% lower incidence rate of breast cancer for women with 25(OH)D concentrations ≥60 vs <20 ng/ml (Rate Ratio = 0.18, P = 0.006). Second, Kaplan-Meier curves for concentrations of <20, 20-39, 40-59 and ≥60 ng/ml were significantly different (P = 0.02), with the highest proportion breast cancer-free in the ≥60 ng/ml group (99.3%) and the lowest proportion breast cancer-free in the <20 ng/ml group (96.8%). The proportion with breast cancer was 78% lower for ≥60 vs <20 ng/ml (P = 0.02). Third, multivariate Cox regression revealed that women with 25(OH)D concentrations ≥60 ng/ml had an 80% lower risk of breast cancer than women with concentrations <20 ng/ml (HR = 0.20, P = 0.03), adjusting for age, BMI, smoking status, calcium supplement intake, and study of origin.

Conclusions: Higher 25(OH)D concentrations were associated with a dose-response decrease in breast cancer risk with concentrations ≥60 ng/ml being most protective.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Breast Neoplasms / blood*
  • Breast Neoplasms / epidemiology
  • Breast Neoplasms / pathology
  • Female
  • Humans
  • Middle Aged
  • Proportional Hazards Models
  • Prospective Studies
  • Randomized Controlled Trials as Topic
  • Risk Factors
  • Vitamin D / analogs & derivatives*
  • Vitamin D / blood*

Substances

  • Vitamin D
  • 25-hydroxyvitamin D

Grants and funding

The 2007 Lappe RCT was funded by the National Institute of Aging. The 2017 Lappe RCT was funded by the National Cancer Institute and Creighton University internal funding. GrassrootsHealth is a nonprofit entity; this project was funded by self-sponsorship by the participants and donations from Bio-Tech Pharmacal, Pure North S’Energy Foundation, and the Vitamin D Society. These funds provided the resources for the study design and data collection for the GRH study and the analysis and interpretations of this pooled analysis. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.