Skip to main content

Archived Comments for: Plasma 25-hydroxyvitamin D and risk of breast cancer in the Nurses' Health Study II

Back to article

  1. The follow-up time was too long to find a correlation

    William B. Grant, Sunlight, Nutrition and Health Research Center

    1 July 2011

    Breast cancer is characterized by rapidly growing tumors. For example, diagnoses are more common in spring and fall due to solar UVB and vitamin D reducing risk in summer and melatonin in winter (1). Thus, it should not be expected that a single serum 25(OH)D level measurement would have good prognostic value several years later. Indeed, a review of case-control and nested case-control studies of breast cancer incidence with respect to serum 25(OH)D level found that follow-up periods less than three years resulted in significant inverse correlations, while studies with longer follow-up periods did not (2).

    In a nested case-control study of breast cancer incidence with respect to oral vitamin D intake, the relative risk of cancer decreased with increasing follow-up time: 0.66 (95% CI, 0.46–0.94) for follow-up periods of 0–5 years, 0.73 (95% CI, 0.53–1.01) for 5–10 years, 0.99 (95% CI, 0.74–1.32) for 10–15 years, and 1.23 (95% CI, 0.86–1.75) for more than 15 years (3).

    Thus, for breast cancer, case-control studies or nested case-control studies with very short follow-up times are required to show the inverse correlation between vitamin D and incidence rates, so the results of this study do not contradict the UVB-vitamin D-cancer hypothesis.

    References

    1. Oh EY, Ansell C, Nawaz H, Yang CH, Wood PA, Hrushesky WJ. Global breast cancer seasonality. Breast Cancer Res Treat. 2010 Aug;123(1):233-43.
    2. Grant WB. Effect of interval between serum draw and follow-up period on relative risk of cancer incidence with respect to 25-hydroxyvitamin D level; implications for meta-analyses and setting vitamin D guidelines, Dermato- Endocrinology, July/August/September 2011 July, Aug Sept.;3(3) epub
    http://www.landesbioscience.com/journals/dermatoendocrinology/article/15364/
    3. Robien K, Cutler GJ, Lazovich D. Vitamin D intake and breast cancer risk in postmenopausal women: the Iowa Women's Health Study. Cancer Causes Control. 2007 Sep;18(7):775-82.

    Competing interests

    I receive or have received funding from the UV Foundation (McLean, VA), the Sunlight Research Forum (Veldhoven), Bio-Tech-Pharmacal (Fayetteville, AR), and the Vitamin D Council (San Luis Obispo, CA).

Advertisement