Inhibition of MADB106 mammary tumor growth by chemotherapeutic drugs in rats of varying folate status. (□), Regular diet; (▨), low folate; (▧), high folate. After 7 weeks on the indicated diet conditions, tumor was injected subcutaneously and six rats per group were treated with cyclophosphamide 50 mg/kg, 5-FU 50 mg/kg, doxorubicin 5 mg/kg, or vehicle alone. Two injections, 96 hours apart, were given when the tumors were palpable. Ninety-six hours after the second injection, tumor growth inhibitions were calculated. Using analysis of variance, the difference between the folate-deficient animals treated with cyclophosphamide and the folate-replete or supplemented rats was significant (P = .048). The Pvalues for 5-FU (.678) and doxorubicin (.442) were not significant.