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


VOL.: 6 (1974) (p. 99)

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

Oestradiol-17b was tested in mice, rats, hamsters and guinea-pigs by subcutaneous injection or implantation. Its administration resulted in an increased incidence of mammary, pituitary, uterine, cervical, vaginal and lymphoid tumours and interstitial-cell tumours of the testis in mice. In rats, there was an increased incidence of mammary and pituitary tumours. In hamsters, malignant kidney tumours occurred with a high incidence in intact or castrated males and in ovariectomized but not in intact females. In guinea-pigs, diffuse fibromyomatous abdominal lesions of uncertain histological interpretation were observed. Subcutaneous injections in neonatal mice resulted in precancerous and cancerous vaginal lesions in later life.

The studies in monkeys could not be assessed since they were limited in group size and duration.

Oestradiol-17b treatment increased the incidence of mammary and pituitary tumours in strains of mice having a spontaneous incidence of these tumours. The spontaneous occurrence can be related either to the presence of a virus or to a particular genetic susceptibility. No evidence of the possible role of a virus has been ascertained for rats.

The role of the hormonal balance in the development and persistence of these tumours and possible synergisms with other carcinogenic factors in increasing the incidence of lymphoid tumours has been discussed (see section, "General Remarks on the Sex Hormones", in this volume).

5.2 Human carcinogenicity data

No case reports or epidemiological studies were available to the Working Group. Epidemiological studies on steroid hormones used in oestrogen treatment 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)

Last updated: 18 March 1998

    See Also:
       Toxicological Abbreviations