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


VOL.: 6 (1974) (p. 191)

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

Norethynodrel was tested alone or in combination with mestranol by the oral route in mice and rats. Alone, it was also tested by subcutaneous implantation in mice; and in combination with mestranol, by subcutaneous injection in rats. A subcutaneous injection study in hamsters and a feeding study in monkeys were of too limited duration to be considered for evaluation.

When given alone, norethynodrel increased the incidence of pituitary tumours in mice of both sexes and of mammary tumours in castrated males of one strain; it also increased the incidence of liver-cell, pituitary and mammary tumours in male rats.

In combination with mestranol, it increased the incidence of pituitary, vaginal and cervical tumours in female mice, of pituitary tumours in male mice, of mammary tumours in castrated male mice, of benign liver-cell tumours in male rats and of malignant mammary tumours in rats of both sexes.

5.2 Human carcinogenicity data

No case reports or epidemiological studies on norethynodrel 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) (Progestins; Combined oral contraceptives)

Last updated: 18 March 1998

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