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


VOL.: 21 (1979) (p. 343)

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

Oestrone was tested in mice by oral administration; in mice, rats and hamsters by subcutaneous injection and implantation; and in mice by skin painting. Its administration resulted in an increased incidence of mammary tumours in mice; in pituitary, adrenal and mammary tumours, as well as bladder tumours in association with stones, in rats; and in renal tumours in both castrated and intact male hamsters.

Oestrone benzoate increased the incidence of mammary tumours in mice following its subcutaneous injection.

Oestrone is embryolethal for preimplantation embryos in some species.

5.2 Human data

No case reports or epidemiological studies on oestrone 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 sufficient evidence for the carcinogenicity of oestrone in experimental animals. In the absence of adequate data in humans, it is reasonable, for practical purposes, to regard oestrone as if it presented a carcinogenic risk to humans. Studies in humans strongly suggest that the administration of oestrogens is causally related to an increased incidence of endometrial carcinoma; there is no evidence that oestrone is different from other oestrogens in this respect.

For definition of the italicized terms, see Preamble Evaluation.

Previous evaluation: Vol. 6 (1974)

Subsequent evaluation: Suppl. 7 (1987) (Steroidal oestrogens)

Last updated: 7 April 1998

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       Toxicological Abbreviations