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


VOL.: 26 (1981) (p. 217)

5. Summary of Data Reported and Evaluation

5.1 Experimental data

5-Fluorouracil was tested by intravenous administration in mice and rats and by oral administration in rats. No evidence of carcinogenicity was found, but the studies suffered from limitations with regard to duration or dose.

5-Fluorouracil can induce embryotoxic and teratogenic effects in several animal species and may be embryolethal in monkeys at doses nontoxic to the mother. The available experimental data on the mutagenicity of 5-fluorouracil are inconclusive; the agent did induce transformation in a mouse cell line.

5.2 Human data

5-Fluorouracil has been used since the late 1950s as the main antineoplastic agent in the treatment of gastrointestinal tumours; it is used frequently in combination with other agents for the treatment of a variety of solid tumours.

Data available to the Working Group were insufficient to evaluate the teratogenic potential of this drug in humans. Data on chromosomal aberrations produced by 5-fluorouracil, though limited, suggest that the drug has clastogenic potential.

5-Fluorouracil has been associated in a few case reports with a variety of subsequent neoplasms. In almost all of these cases, the drug was given together with other agents known or suspected of being carcinogens. No epidemiological study was available to the Working Group.

5.3 Evaluation

There was no evidence for the carcinogenicity of 5-fluorouracil in the limited studies in experimental animals. The data from case reports in humans were insufficient to arrive at a conclusion.

On the basis of the available data, no evaluation could be made of the carcinogenic risk of 5-fluorouracil to humans.

Subsequent evaluation: Suppl. 7 (1987)

Last updated: 8 April 1998

    See Also:
       Toxicological Abbreviations
       Fluorouracil, 5-  (IARC Summary & Evaluation, Supplement7, 1987)