Abstract:Objective:To study the correlation among circulating estrone (E1), 2-hydroxyestrone(2-OHE1), 16α-hydroxyestrone(16α-OHE1), the ratio of 2-hydroxyestrone to 16α hydroxyestrone(2-OHE1∶16α-OHE1) and breast cancer in postmenopausal women. Methods:Serum levels of E1,2-OHE1,16α-OHE1 were measured by ELISA method in 40 cases of breast cancer,21 cases of breast fibroadenoma and 19 cases of mastopathy in postmenopausal women; the ratio of 2-OHE1 to 16α-OHE1 was calculated. Results:There were no significant difference in circulating levels of E1,16α-OHE1 and the ratio of 2-OHE1 to 16α-OHE1 in three groups (P＞0.05). The levels of 2-OHE1 were significantly different in three groups（P<0.05）; it’s level in breast cancer group was significantly lower than that in mastopathy group（P<0.05）. Circulating levels of E1,2-OHE1,16α-OHE1 and the ratios of 2-OHE1 to 16α-OHE1 were not associated with ER, HER2, axillary lymph node status or tumor size (P＞0.05). Breast cancer risk was not associated with the ratio of 2-OHE1 to 16α-OHE1(Odds ratio was 0.828, 95% confidence interval was 0.425~1.611, P＞0.05)，but it was negatively associated with the level of 2-OHE1(Odds ratio was 0.418, 95% confidence interval was 0.180~0.971, P<0.05).Conclusion：The results suggest that the level of 2-OHE1 is negatively associated with breast cancer risk, and do not support that the ratio of 2-OHE1 to 16α-OHE1 predicts breast cancer risk.
