A critical appraisal of intratracheal instillation of benzo[a]pyrene to Syrian golden hamsters as a model in respiratory tract carcinogenesis.

Several experimental models have been developed to study respiratory tract carcinogenesis. The most widely applied in vivo model uses Syrian golden hamsters which receive intratracheal instillations of a suspension of benzo[a]pyrene (B[a]P) particles attached to ferric-oxide (Fe2O3) particles in saline; it was first described by Saffiotti et al. [1]. This model has several benefits compared with other experimental models; however, the large number of variables affecting the tumour response is a clear disadvantage because the tumour response is difficult to control. In this review, we describe a systematic analysis of various variables that may influence the tumour response of the respiratory tract with the aim to further standardize the method and increase, through that, its suitability and predictability. The most important variables influencing the tumour response, as shown by statistical analysis of 29 representative studies, turned out to be the administered dose and the particle size. Both these variables influence the actual dose and the contact-time of the B[a]P particles with the target cells. The present study does not support the widespread opinion that ferric-oxide particles enhance the tumour response of the respiratory tract. In conclusion to the present analysis, some recommendations are made which probably increase the predictability of the model.