International Agency for Research on Cancer (IARC) - Summaries & Evaluations
VOL.: 21 (1979) (p. 491)
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
Progesterone was tested by subcutaneous and intramuscular injection in
mice, rats, rabbits and dogs and by subcutaneous implantation in mice
and rats. It was tested alone in mice and dogs; in rats and rabbits it
was always given in combination with other sex hormones.
When given alone, progesterone increased the incidence of ovarian,
uterine and mammary tumours in mice; the data from dogs were
insufficient to evaluate carcinogenicity.
Neonatal treatment with progesterone enhanced the occurrence of
precancerous and cancerous lesions of the genital tract and resulted
in increased mammary tumorigenesis in female mice.
5.2 Human data
No case reports or epidemiological studies on exogenous progesterone
were available to the Working Group.
There is limited evidence for the carcinogenicity of progesterone in
experimental animals. In the absence of epidemiological data, no
evaluation of the carcinogenicity of progesterone to humans can be
For definition of the italicized terms, see Preamble Evaluation.
Previous evaluation: Vol. 6 (1974)
Subsequent evaluation: Suppl. 7 (Progestins)
Last updated: 7 April 1998