Evaluation of effect of levamisole on feline mammary cancer.

Seventy-three cats with untreated malignant mammary tumors (64 with adenocarcinoma, 9 with carcinoma in situ) were selected for study. All cats were clinically staged and stratified on the basis of tumor volume. Following radical mastectomy, the cats were randomized for treatment with either levamisole or placebo. There was no significant difference in either survival time or recurrence rate between the levamisole and placebo groups. The most significant prognostic factor was tumor volume: Cats with small tumors had a significantly enhanced survival time (p = 0.00006) and lower recurrence rate (p = 0.00004). Breed of cat was also an important prognostic factor; the domestic short-haired cats had a significantly (p = 0.038) longer survival time than the cats of other breeds.