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


VOL.: 21 (1979) (p. 431)

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

Megestrol acetate alone or with ethinyloestradiol was tested in mice, rats and dogs by oral administration and in rats by subcutaneous administration. It produced mammary tumours in dogs when tested alone and in mice when tested in combination with ethinyloestradiol. Experiments in which it was tested in rats in combination with ethinyloestradiol were negative or inadequate.

5.2 Human data

No case reports or epidemiological studies on megestrol acetate 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

There is limited evidence for the carcinogenicity of megestrol acetate in dogs. 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.

For definition of the italicized terms, see Preamble Evaluation.

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

Last updated: 7 April 1998

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