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 progestin.

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

    See Also:
       Toxicological Abbreviations
       Ethinyloestradiol (IARC Summary & Evaluation, Volume 21, 1979)