Odds ratios and 95% confidence intervals for breast cancer by serum 25-hydroxyvitamin D levels.

1Serum 25-hydroxyvitamin D (25OHD) concentrations were adjusted by the week of blood collection time in a year by locally weighted multinomial regression. The three levels were defined as follows: deficient, <20.0 ng/mL; insufficient, 20.0–29.9 ng/mL; sufficient, ≥30.0 ng/mL. 2Odds ratios (OR) ad 95% confidence intervals (CI) were adjusted for age and BMI. Further adjustment for physical activity did not significantly change the results (data not shown).