Effect of folate status on the toxicity of cancer chemotherapy. Three groups of 18 rats each were maintained on the indicated folate diets. After 7 weeks, six animals from each group were treated with either cyclophosphamide 62.5 mg/kg (top), 5-FU 75 mg/kg (middle), or doxorubicin 7.5 mg/kg (bottom). Drugs were injected three times at 96-hour intervals (arrows). Survivals were significantly different for cyclophosphamide (P = .0084) and 5-FU (P = .025), but not for doxorubicin (P = .12) by the Log-Rank test.