The reduced glutathione (GSH) levels in the hepatic tissues, extent of lipid peroxidation in the liver, kidney and brain, and alterations in the activity of glutathione peroxidase (GPX) in the hepatic tissues were monitored in mice bearing a transplantable ascitic lymphoma. These markers showed substantial alterations during the height of tumour progression when compared to controls. The GSH level, extent of lipid peroxidation, and GPX activity increased sharply after approximately 2 weeks following inoculation of ascitic cells. This was followed by a steady decline in all markers and death occurred around day 32 after inoculation.

This study attempts to determine whether selenomethionine treatment can improve the survival time of mice inoculated with Dalton’s lymphoma (DL) and thereby to identify phase/ phases of the neoplastic processes at which selenium exerts its maximal action as an anticancer agent. Accordingly, a maximum of 30.76 and 143% increase in survival was brought about by treatment of selenomethionine prior to lymphoma transplantation, in comparison to mice receiving selenome-thione supplementation concurrently with inoculation of DL, and those tumor-bearing mice receiving no supplementation, respectively. Beneficiality of selenomethionine has also been studied by monitoring the continuous changes brought about by this compound on hepatic total cytochrome P-450 and bs content, NADPH cytochrome c reductase, UDP glucuronyl transferase and glutathione S-transferase (GST) activities. These are important biotransformation enzymes and are altered significantly in neoplasia. The drastic increase in all the markers studied, excepting GST, was effectively counteracted by selenomethionine treatment (more before than concurrently), which sufficiently delayed and controlled the increase in those xenobiotic indices. The 112 and 78.78% induction in GST activity brought about by prior and concurrent treatment of selenomethionine, respectively, confirms the fact that in-ducers of GSTs are often antitumorigenic.