OECD Detailed Review Paper (DRP) number 31 on "Cell Transformation Assays for Detection of Chemical Carcinogens": main results and conclusions.

The Detailed Review Paper (DRP) number 31 of the Organisation for Economic Co-operation and Development (OECD) analyses the performance of the three models used in Cell Transformation Assays (CTAs) to screen the carcinogenic potential of chemicals: the Syrian hamster embryo (SHE) cells, and the mouse cell lines BALB/c 3T3 and C3H10T1/2. The CTA results have been compared to results from recent genotoxicity tests using mammalian and non-mammalian cell systems. The performance of the CTAs in predicting carcinogenic potential has been established on several hundreds of chemicals, comprising organic and inorganic substances. The results have been analysed and the chemicals classified as rodent and/or human carcinogens. Based on this comparison and on their performance - concordance, sensitivity, specificity, positive and negative predictive capacity, and evidence for intra- and inter-laboratory reproducibility - OECD recommended that the CTAs using the SHE cells (carried out at physiological or acidic pH) and the BALB/c 3T3 cell line should be developed into OECD test guidelines. The CTA using the C3H10T1/2 cell line was considered to be useful to elucidate molecular mechanisms of cell transformation at the genomic and transcriptomic level. However, due to the limited data available on reproducibility, a test guideline was not recommended at that time.