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


VOL.: 21 (1979) (p. 519)

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

Testosterone and its esters were tested in mice, rats and hamsters, by subcutaneous injection and/or implantation, and in rabbits by intramuscular injection.

Testosterone propionate implanted subcutaneously in mice induced cervical-uterine tumours, which metastasized in some cases; in rats, metastasizing prostatic adenocarcinomas were induced in males.

Neonatal treatment of female mice by subcutaneous injection of testosterone induced lesions of the genital tract and increased the mammary tumour incidence when the animals were adult. 5b-Dihydrotestosterone, which is considered to be hormonally inactive in adults, also increased the incidence of mammary tumours in mice when given neonatally by subcutaneous injection.

Testosterone is embryolethal in pre- and postimplantation embryos and causes virilization in female offspring.

5.2 Human data

No case reports or epidemiological studies on testosterone alone were available to the Working Group. There are limited data concerning the possible long-term effects of androgenic-anabolic steroids, which are related to testosterone. An association between these synthetic androgenic steroids and the occurrence of hepatocellular carcinomas has been suggested, but the evidence is inconclusive.

5.3 Evaluation

There is sufficient evidence for the carcinogenicity of testosterone in experimental animals. In the absence of adequate data in humans, it is reasonable, for practical purposes, to regard testosterone as if it presented a carcinogenic risk to humans. The only related data in humans, although insufficient for an evaluation, concern the possible long-term effects of androgenic anabolic-steroids.

For definition of the italicized terms, see Preamble Evaluation.

Subsequent evaluation: Vol. 6 (1974)

Subsequent evaluation: Suppl. 7 (1987) (Androgenic (anabolic) steroids)

Last updated: 7 April 1998

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       Toxicological Abbreviations