The influence of subsequent dehydroepiandrosterone, diaminopropane, phenobarbital, butylated hydroxyanisole and butylated hydroxytoluene treatment on the development of preneoplastic and neoplastic lesions in the rat initiated with di-hydroxy-di-n-propyl nitrosamine.

The comparative modifying potential of dehydroepiandrosterone (DHEA), diaminopropane (DAP), phenobarbital (PB), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on the development of lesions initiated by dihydroxy-di-n-propyl nitrosamine (DHPN) in F344 rats were investigated. DHEA, BHA and BHT were all associated with significant reduction in numbers of glutathione-S-transferase P form (GST-P) positive foci in the liver whereas PB brought about their enhanced development. BHT and PB exerted promoting activity on the incidence of thyroid adenomas while DAP similarly increased lung adenoma formation. The results illustrate the advantages to be gained from two stage experiments using broad spectrum carcinogen initiation for comparative analysis of 'modifiers' of the neoplastic process and suggest that studies of enzyme alteration within putative preneoplastic lesions may be directly relevant to elucidation of mechanisms underlying such modification.