Low Vitamin D levels linked to high risk of premenopausal breast cancer

A prospective study led by researchers from the University of California, San Diego School of Medicine has found that low serum vitamin D levels in the months preceding diagnosis may predict a high risk of premenopausal breast cancer.

The study of blood levels of 1,200 healthy women found that women whose serum vitamin D level was low during the three-month period just before diagnosis had approximately three times the risk of breast cancer as women in the highest vitamin D group.  The study is currently published online in advance of the print edition of the journal Cancer Causes and Control.

Several previous studies have shown that low serum levels of vitamin D are associated with a higher risk of premenopausal breast cancer.  ''While the mechanisms by which vitamin D could prevent breast cancer are not fully understood, this study suggests that the association with low vitamin D in the blood is strongest late in the development of the cancer, ''said principal investigator Cedric Garland, DrPH, FACE, professor in the Department of Family and Preventive Medicine at UC San Diego.

Analyses of vitamin D levels measured more than 90 days before diagnosis have not conclusively established a relationship between serum levels and risk of premenopausal breast cancer in the present cohort.

However, this new study points to the possibility of a relevant window of time for cancer prevention in the last three months preceding tumor diagnosis –a time physiologically critical to the growth of the tumor.

According to Garland, this is likely to be the point at which the tumor may be most actively recruiting blood vessels required for tumor growth.  ''Based on these data, further investigation of the role of vitamin D in reducing incidence of premenopausal breast cancer, particularly during the late phases of its development, is warranted,'' he said.