Repeated Measurements of Serum Carotenoid, Retinol and Tocopherol Levels in Relation to Colorectal Cancer Risk in the Women's Health Initiative

Eur J Clin Nutr. 2012 May;66(5):549-54. doi: 10.1038/ejcn.2011.207. Epub 2011 Dec 14.

Abstract

Background/objective: Previous cohort studies examining the association of serum antioxidant levels and risk of colorectal cancer have used a single (baseline) measurement only. In the present study, we assessed the association of serum levels of eight antioxidant nutrients in relation to risk of colorectal cancer, using repeated measurements.

Subjects/methods: Data on a subsample of women in the Women's Health Initiative with repeated measurements of serum retinol, α-carotene, β-carotene, β-cryptoxanthin, lutein+zeaxanthin, lycopene, α-tocopherol and γ-tocopherol during follow-up were included in the analysis. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CIs).

Results: Among 5477 women with baseline serum antioxidant values, 88 incident cases of colorectal cancer were identified over a median follow-up time of 12 years. Serum antioxidants measured at baseline generally showed no association with risk of colorectal cancer, although serum β-carotene at baseline showed a non-significant inverse association with colon cancer alone. Furthermore, using the repeated measurements of β-carotene, the average of all measurements was inversely associated with risk of both colorectal and colon cancer: HRs for highest vs lowest tertile 0.54, 95% CI 0.31-0.96, and 0.47, 95% CI 0.25-0.88, respectively. No associations were seen with other antioxidant nutrients in the repeated measure analyses.

Conclusions: In this study, baseline levels of antioxidant nutrients were not associated with risk of colorectal or colon cancer; however, using repeated measures, a relatively high serum level of β-carotene (average of all measurements) was inversely associated with risk of colon and colorectal cancer in postmenopausal women.

MeSH terms

  • Aged
  • Antioxidants / metabolism*
  • Carotenoids / blood
  • Colonic Neoplasms / blood*
  • Colonic Neoplasms / prevention & control
  • Colorectal Neoplasms / blood*
  • Colorectal Neoplasms / epidemiology
  • Colorectal Neoplasms / prevention & control
  • Female
  • Humans
  • Incidence
  • Middle Aged
  • Nutrition Assessment
  • Nutritional Status*
  • Proportional Hazards Models
  • Risk Factors
  • Tocopherols / blood
  • Vitamin A / blood
  • Women's Health
  • beta Carotene / blood*

Substances

  • Antioxidants
  • beta Carotene
  • Vitamin A
  • Carotenoids
  • Tocopherols