What is the effect of prolactin on a women's risk for breast cancer?

Updated: Dec 26, 2019
  • Author: Graham A Colditz, MD, DrPH; Chief Editor: Chandandeep Nagi, MD  more...
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Substantial laboratory evidence suggests that prolactin could play a role in breast carcinogenesis. Prolactin receptors have been found on more than 50% of breast tumors, and prolactin increases the growth of both normal and malignant breast cells in vitro, although these findings have not been entirely consistent. Prolactin administration is well documented to increase mammary tumor rates in mice.

A number of small case-control studies of prolactin levels and breast cancer risk have been conducted; the largest of these included 66 cases. To date, only two prospective studies have been conducted. In the first, of 40 postmenopausal breast cancer cases, [36] women in the top quintile of prolactin levels had a nonsignificant 63% higher risk of breast cancer compared to those in the bottom quintile. In a prospective analysis of prolactin and breast cancer risk from the Nurses' Health Study, a significant doubling of risk was seen comparing top to bottom quintile. [37]

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