I'm posting this because so many of us are taking vitamin D3 along with calcium and K2 and the study is from 2021 so recent.

"1,25-Dihydroxycholecalciferol, the hormonally active vitamin D3 metabolite, is known to exhibit therapeutic effects against breast cancer, mainly by lowering the expression of estrogen receptors and aromatase activity."

To read the study, net search the title"Vitamin D Compounds PRI-2191 and PRI-2205 Enhance Anastrozole Activity in Human Breast Cancer Models"