No abstract

Between 1968 and 1976 a total of 5162 women volunteers were enrolled into a prospective study conducted on the Island of Guernsey. Up to February 1990 145 women subsequently developed breast cancer. Blood samples were taken at the time of enrollment and prolactin levels were known for 85% of the volunteers. In calculating the relationship between blood prolactin levels and subsequent breast cancer risk, women were excluded if they had a hysterectomy or an oophorectomy or had cancer at any site before enrollment. The final analysis was based on 2596 premenopausal and 1180 naturally postmenopausal women and, of these respectively, there were 71 and 40 volunteers who subsequently developed breast cancer. The total follow-up for these two groups was 49,941 and 22,360 woman-years, respectively. In assessing the relationship between blood prolactin levels and risk of subsequent breast cancer the cohort was divided into quintiles according to prolactin concentration and relative risks (RR) were estimated. In calculating these values possible confounding by age at entry, age at menarche, parity, age at first birth, years since menopause, body build, history of benign breast disease and family history of breast cancer were taken into consideration. There was no significant relation between risk of breast cancer and prolactin in either pre- or postmenopausal women. Hence prolactin appears not to be an important determinant of breast cancer risk.

No abstract

No abstract

Plasma prolactin has been measured in over 3,500 women volunteers from a normal population. In premenopausal women there was a significant decrease in prolactin levels with increasing parity. However, this effect was transitory since plasma prolactin concentration rose with increasing time after the birth of the last child. There were no significant differences in prolactin levels with respect to height and weight, although overweight compared to underweight women had approximately 15% more plasma prolactin. If prolactin is a carcinogen, then these results are in keeping with the epidemiological findings that multiparity affords protection and that age at last delivery is a risk factor in the development of breast cancer.