International Agency for Research on Cancer (IARC) - Summaries & Evaluations
VOL.: 6 (1974) (p. 77)
5. Summary of Data Reported and Evaluation
(N.B.: This section should be read in conjunction with the section
'General Conclusions on Hormones'.)
5.1 Animal carcinogenicity data
Ethinyloestradiol was tested in mice and rats by the oral route; in
most cases it was administered in combination with progestins.
Administered alone to mice, it increased the incidence of pituitary
tumours and malignant mammary tumours in both males and females and
produced malignant tumours of the uterine fundus and the cervix in
females. In rats, it increased the incidence of benign liver-cell
tumours in both males and females and produced malignant liver-cell
tumours in females.
When ethinyloestradiol was given in combination with some progestins,
excess incidences of malignant tumours of the uterine fundus in female
mice and of benign and/or malignant mammary tumours in male rats were
observed; in female rats the combinations reduced but did not prevent
the incidence of malignant liver-cell tumours when compared with that
produced by ethinyloestradiol alone.
Mammary fibroadenomas were produced in female rats following
subcutaneous injection of a combination of ethinyloestradiol with a
5.2 Human carcinogenicity data
No case reports or epidemiological studies on ethinyloestradiol alone
were available to the Working Group. Epidemiological studies on
steroid hormones used in oestrogen-progestin contraceptive
preparations have been summarized in the section, "Oestrogens and
Progestins in Relation to Human Cancer" in this volume.
Subsequent evaluations: Vol. 21 (1979);
Suppl. 7 (1987)
Last updated: 18 March 1998