International Agency for Research on Cancer (IARC) - Summaries & Evaluations
OESTRADIOL-17b, OESTRADIOL 3-BENZOATE,
OESTRADIOL DIPROPIONATE, OESTRADIOL-17b-VALERATE
VOL.: 21 (1979) (p. 279)
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
Oestradiol-17b and its esters were tested in mice, rats, hamsters,
guinea-pigs and monkeys by subcutaneous injection or implantation and
in mice by oral administration. Its subcutaneous administration
resulted in increased incidences 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/or pituitary tumours. In hamsters, a high incidence of
malignant kidney tumours occurred in intact and castrated males and in
ovariectomized females, but not in intact females. In guinea-pigs,
diffuse fibromyomatous uterine and abdominal lesions were observed.
Oral administration of oestradiol-17b in mice led to an increased
mammary tumour incidence. Subcutaneous injections in neonatal mice
resulted in precancerous and cancerous cervical and vaginal lesions in
later life and an increased incidence of mammary tumours.
Oestradiol-17b has teratogenic actions on the genital tract and
possibly on other organs and impairs fertility.
5.2 Human data
No case reports or epidemiological studies on oestradiol-17b 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'.
There is sufficient evidence for the carcinogenicity of oestradiol-17b in experimental animals. In the absence of adequate data in
humans, it is reasonable, for practical purposes, to regard
oestradiol-17b 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 oestradiol-17b 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: 23 April 1998