NEW DIRECTIONS FOR PREDICTING CARCINOGENESIS

Carcinogenicity testing today normally includes conducting 2-yr studie s of rats and mice of both sexes and following widely accepted procedu res for husbandry, selection of dose levels, pathology and toxicity ob servations, and statistical interpretation of tumor data. These studie s are usually preceded by tests for genetic toxicity and subchronic to xicity studies to select dose levels for the 2-yr studies. While these data are used for quantitative risk assessment, the mechanistic basis for effects is usually unknown, and such series of studies are very e xpensive and require five or more years to conduct. Alternate approach es are being developed that would provide more mechanistic information and perhaps would permit decisions to be made about carcinogenic pote ntial without the need to conduct 2-yr studies of rats and mice of bot h sexes. Decisions could be based on a profile of data rather than the result of one test. Regulatory acceptance of new approaches for carci nogenicity testing is critical to future progress in the field of carc inogenesis. (C) 1997 Wiley-Liss, Inc.