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
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'.
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