By Reuters Staff

NEW YORK (Reuters Health) – Sufficient levels of vitamin D
might help protect Hispanic and potentially Black women from
developing breast cancer, new research suggests.

“Although Black/African American women and Hispanic/Latina
women have lower circulating vitamin D levels than non-Hispanic
white women, few studies have examined the association between
vitamin D and breast cancer within these racial/ethnic groups,”
the study team notes in the journal Cancer.

Dr. Katie O’Brien and colleagues with the National Institute
of Environmental Health Sciences measured 25-hydroxyvitamin D
(25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)2D) levels in
blood samples from 290 Black/African American women and 125
non-Black Hispanic/Latina women who developed breast cancer, and
1,084 Black/African American women and 461 Hispanic/Latina women
who did not develop breast cancer.

Over an average follow-up of 9.2 years, women with
circulating 25(OH)D levels above the clinical cut point for
deficiency (20.0 ng/mL) had a 21% lower breast cancer rate than
women with concentrations below this cut point, although the
result fell short of statistical significance (hazard ratio,
0.79; 95% CI, 0.61 to 1.02).

The inverse association was strongest in Hispanic/Latina
women (HR, 0.52; 95% CI, 0.29 to 0.93), with a weaker
association seen in Black/African American women (HR, 0.89; 95%
CI, 0.68 to 1.18; P for heterogeneity = 0.13).

There was no clear dose-response relationship between
24,25(OH)2D or the 24,25(OH)2D to 25(OH)D ratio and breast
cancer risk.

The associations between 25(OH)D and breast cancer did not
vary by tumor characteristics.

“Although our sample size limited our ability to detect
small differences, our findings do not support our hypothesis
that vitamin D might explain why Black/African American women
are more likely to be diagnosed with ER-negative disease,” the
study team says.

“Although many questions remain, these findings add to the
evidence that vitamin D protects against breast cancer and
highlight a possible path for intervention in 2 racial/ethnic
groups with a high prevalence of vitamin D deficiency,” they
write.

“Because women who identify as members of these groups have
lower vitamin D levels, on average, than non-Hispanic white
women, they could potentially receive enhanced health benefits
from interventions promoting vitamin D intake,” Dr. O’Brien
comments in a news release.

“However, questions remain about whether these associations
are truly causal and, if so, what levels of vitamin D are most
beneficial,” she adds.

The study had no commercial funding and the authors have
declared no relevant conflicts of interest.

SOURCE: https://bit.ly/3Ms8bRf Cancer, online April 25,
2022.