Oestrogen use and survival in endometrial cancer.

Of 860 women with endometrial cancer registered in a regional cancer treatment centre, 259 (30%) gave a history of oestrogen use for 6 months or more at some time before diagnosis, and 568 (66%) were non-users. OEstrogen use was associated with younger age, earlier stage, lower grade of tumour, less common myometrial invasion, and preferred treatment including radiation and hysterectomy. The 5-year survival of oestrogen users was 92 +/- 2% compared with 68 +/- 2% for non-users. Further analysis controlling for differences in the distribution of the variables associated with survival showed that for women who have endometrial cancer, the risk of any death for non-users is approximately 2-7 times greater than for oestrogen users, and the risk of death from endometrial cancer is 5.4 times greater for non-users. A history of oestrogen use is not associated with superior survival of women who have poorly differentiated tumours or myometrial invasion.