Antitumor activity of 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) and 1-(2-chloroethyl)-3-(4-methyl-cyclohexyl)-1-nitrosourea (MeCCNU) on Yoshida sarcoma ascites cells implanted into the colon wall of rats.

Three thousand Yoshida sarcoma cells were inoculated into the wall of the descending colon of each of 120 male Sprague-Dawley rats. On day 8 after the tumor implantation, the animals were at random divided into four groups of 30 rats each. The effect of cyclophosphamide (70 mg/kg), BCNU (25 mg/kg), and methyl-CCNU (45 mg/kg) after single i.p. application was investigated. The Yoshida sarcoma transplanted into the colon is sensitive to all three chemotherapeutic drugs. At the doses given cyclophosphamide showed the best results. The two nitrosoureas had a comparable antitumor activity but methyl-CCNU showed a more distinct toxic effect. The introduction of this model for testing new cytostatics in animal experiments is discussed.