“Low levels of vitamin D were recorded among patients with breast cancer compared with healthy controls. Moreover, low vitamin D levels were common at breast cancer diagnosis and were associated with a poor prognosis; about 94% women with vitamin D level less than 20 ng/mL develop metastases and 73% die of the advanced disease.”

“….retrospective and prospective epidemiologic studies revealed that vitamin D deficiency is associated with increased breast cancer risk.”

M.Atoum, F.Alzoughool
Vitamin D and Breast Cancer: Latest Evidence and Future Steps
Breast Cancer: Basic And Clinical Research – December 20, 2017

“…..vitamin D deficiency may account for several thousand premature deaths from colon, breast, ovarian, and prostate cancer annually.”

C.F.Garland, et al
The Role of Vitamin D in Cancer Prevention
American Journal Of Public Health – Volume 96 #2 – February 2006 – page 252

“….a new study correlates breast cancer survival rates with levels of vitamin D “
“Some studies have suggested that the active metabolite of vitamin D – known as calcitriol – may be anticancerous. Administering calcitriol in mice has been shown to stop the proliferation and growth of cancer cells, reduce tumor blood vessel formation, and stimulate cell death……..some clinical and preclinical studies indicate that avoiding vitamin D deficiency and taking vitamin D supplements might be a cost-effective and safe way to prevent cancer and improve prognosis in patients already diagnosed with the illness.”