International Agency for Research on Cancer (IARC) - Summaries & Evaluations


VOL.: 21 (1979) (p. 479)

5. Summary of Data Reported and Evaluation

(N.B. - This section should be read in conjunction with the General Remarks on Sex Hormones and with the General Conclusions on Sex Hormones.)

5.1 Experimental data

Norgestrel was tested in mice and rats alone or in combination with ethinyloestradiol by oral administration. There was no increase in the incidence of tumours in either species.

Norgestrel is embryolethal for pre- and postimplantation embryos in rats.

5.2 Human data

No case reports or epidemiological studies on norgestrel alone were available to the Working Group. Epidemiological studies on steroid hormones used in oestrogen-progestin oral contraceptive preparations have been summarized in the section, 'Oestrogens and Progestins in Relation to Human Cancer'.

5.3 Evaluation

The available data in experimental animals and humans are insufficient to evaluate the carcinogenicity of norgestrel. In humans, oral contraceptives containing oestrogens in combination with progestins have been related causally to an increased incidence of benign liver adenomas and a decreased incidence of benign breast disease.

Previous evaluation: Vol. 6 (1974)

Subsequent evaluation: Suppl. 7 (1987) (Progestins; combined oral contraceptives)

Last updated: 7 April 1998

    See Also:
       Toxicological Abbreviations
       Norgestrel (IARC Summary & Evaluation, Volume 6, 1974)