Urine estrogen profiles in European countries with high or low breast cancer rates

Abstract

Urine estrogens of women in two age groups, 15 18 and 30-39, were measured in four northern European countries where breast cancer rates are high, two southern European countries where they are low, and in Finland, a northern country where incidence rates are comparable to those of the southern countries and mortality rates are intermediate. The estriol ratio (the ratio of the concentration of estriol to the sum of those of estrone and estradiol) was lower in the high-risk countries than in the low-risk areas in both age-groups and in both the follicular and luteal phases of the menstrual cycle. In two of the four comparisons the difference was statistically significant. This provides modest support to the hypothesis that a population's breast cancer risk is inversely related to the estriol ratios of its young women. However, the data from Finland are not consistent with this hypothesis, the Finnish women having lower mean estriol ratios than the women in the high-risk areas. The pregnanediol levels of the young Finnish women were also unusually low, suggesting a high frequency of anovulatory menstrual cycles.