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