[Chronotherapy of breast cancer induced by N-nitrosomethylurea in the rat. I. Effect of a high dose of cyclophosphamide administered at 8:00 and 14:00 hours].

Abstract

The administration of cyclophosphamide (200 mg/kg) intraperitoneally produces a high mortality in Wistar rats bearing mammary tumors induced by N-methylnitrosourea. The effect is more marked when the drug is administered at 8:00 A.M. than when given at 2:00 P.M. The injection of cyclophosphamide at 2:00 P.M. slowers the tumor growth, the effect being significative after two weeks compared with the control animals, and after four weeks when compared with the animals receiving the drug at 8:00 A.M.