To the Editor The report by Yao et al1 of associations of higher vitamin D levels with lower risk of breast cancer morbidity and mortality warrants comment.
First, Kaplan-Meier survival curves by tertiles of serum 25-hydroxyvitamin D (25OHD) levels for the 4 outcomes (1) only begin to be slightly different after day 1500 or 2000 and (2) are not consistent for the 3 tertiles (eg, recurrence-free survival vs breast cancer–specific survival).
Braillon A. Vitamin D and Breast Cancer SurvivalThe Good and the Bad. JAMA Oncol. Published online June 08, 2017. doi:10.1001/jamaoncol.2016.6792