Ethnic differences in post-menopausal plasma oestrogen levels: high oestrone levels in Japanese-American women despite low weight

Breast cancer incidence in Japanese-American women is approaching that of U S Whites. We investigated whether this shift is paralleled by similar post- menopausal plasma hormone levels in the two ethnic groups. We also included African-American and Latina women to further our understanding of possible ethnic differences in oestrogen metabolism. We measured androstenedione (A ), oestrone (E1) and oestradiol (E2) in 30 Japanese-American, 39 non-latina White ('White'), 66 African-American and 58 Latina women. The (age adjuste d) geometric mean E1 levels were 34 pg ml(-1) in Japanese-Americans, 28 pg ml(-1) in Whites, 35 pg ml(-1) in African-Americans and 31 pg ml(-1) in Lat inas. After adjustment for body mass index, Japanese-Americans had the high est mean E1 value of all groups and this was statistically significantly gr eater than the value for Whites (Pt-test = 0.05). The geometric mean A conc entrations were also highest in Japanese-Americans. There was little ethnic difference in E2 levels, in conclusion, post-menopausal plasma oestrogen l evels in Japanese-American women are at least as high as those in Whites. ( C) 2000 Cancer Research Campaign.