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Lower vitamin D status may help explain why black women have a higher risk of invasive breast cancer than white women
Breast Cancer Research volume 22, Article number: 24 (2020)
To the Editor:
The recent article by Dania and colleagues reported that black women had a 33% increased risk for subsequent invasive breast cancer after diagnosis of lobular carcinoma in situ (LCIS) during 90 months of follow-up . The authors suggested that further research might better understand the contributors to racial differences in developing invasive breast cancer following LCIS.
The authors did not consider the role of vitamin D in affecting risk of invasive breast cancer. Black women living in the USA have much lower 25-hydroxyvitamin D [25(OH)D] concentrations than do white women due to their darker skin .
There is evidence that breast cancer risk among black women is affected by 25(OH) D concentrations. For example, a prospective study from the Black Women’s Health Study found that the incidence rate ratio for invasive breast cancer for lowest vs. highest quartile of predicted 25(OH) D was 1.23 (95% CI, 1.04, 1.46) . For another study, see Ref. 8 in . More recently, Ref. 37 in  reported that in a clinical trial in which participants in the treatment arm were given 2000 IU/d vitamin D3, black participants had a 23% reduction [hazard ratio = 0.77 (95% CI, 0.59, 1.01)] in overall cancer incidence.
The evidence that vitamin D reduces risk of breast cancer was reviewed recently . The strongest observational evidence comes from case-control studies. Breast cancer can progress rapidly to detectable size, and breast cancer is the only type of cancer with pronounced seasonal variation in diagnosis, with higher rates in spring and fall (Ref. 12 in ). One reason given for rejecting case-control studies as evidence for the effects of vitamin D on risk is that the existence of breast cancer, even if not diagnosed, may affect serum 25(OH) D concentration. Several studies are presented in  indicating that there is little evidence that disease status, including cancer and infectious diseases, significantly affects 25(OH) D concentration. However, the fact that the 25(OH) D concentration-breast cancer incidence relationships in 11 studies from seven countries have the same shape argues against that concern .
The proposed mechanisms whereby vitamin D metabolites reduce the risk of breast, colorectal, prostate, and overall cancer include surveillance of cells, reduced angiogenesis around tumors, and anti-metastasis actions (see references in [3, 4]). However, higher 25(OH) D concentrations have also been found associated with increased risk of colorectal and prostate cancer . Further research is indicated to evaluate the UVB-vitamin D-cancer hypothesis.
Availability of data and materials
All data and material have been referenced and are readily available.
Dania V, Liu Y, Ademuyiwa F, Weber JD, Colditz GA. Associations of race and ethnicity with risk of developing invasive breast cancer after lobular carcinoma in situ. Breast Cancer Res. 2019;21(1):120.
Ginde AA, Liu MC, Camargo CA Jr. Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med. 2009;169(6):626–32.
Palmer JR, Gerlovin H, Bethea TN, Bertrand KA, Holick MF, Ruiz-Narvaez EN, Wise LA, Haddad SA, Adams-Campbell LL, Kaufman HW, et al. Predicted 25-hydroxyvitamin D in relation to incidence of breast cancer in a large cohort of African American women. Breast Cancer Res. 2016;18(1):86.
Grant WB. Review of recent advances in understanding the role of vitamin D in reducing cancer risk: breast, colorectal, prostate, and overall cancer. Anticancer Res. 2020;40(1):491–9.
Grant WB, Boucher BJ. Randomized controlled trials of vitamin D and cancer incidence: a modeling study. PLoS One. 2017;12(5):e0176448.
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Grant, W.B. Lower vitamin D status may help explain why black women have a higher risk of invasive breast cancer than white women. Breast Cancer Res 22, 24 (2020). https://doi.org/10.1186/s13058-020-01261-2