Vel Pathol 30:20-27 (1993) Prognostic Factors in Canine Mammary Tumors: A Multivariate Study of 202 Consecutive Cases

Abstract. Th e prognostic vari ables of 223 consecutively sampled spontaneous mammar y tum ors from fem ale dogs were studied. Th ese variabl es included flow cyto metric DNA analysis and cell proliferat ion mea sured as cells in S-ph ase rate eva luated from DNA histogram s. Th e dogs were surgically treated, in mos t cases with unilat eral mastectom y (all mam mary glands), and 202 of the 223 dogs were studied tem porally following surgery. Univa riate analysis with correction for age indicated that the variables of lymph node metastasis, elevated S-phase rat e, presence of a sarcoma, DNA aneuploidy, and ulcerati on and infiltrative growth into und erlying tissue had a statistically significant negat ive influence on the survival rates of dogs with a diagnosed malignant tum or. Simi lar results were obtained from tests on all dogs, but tumo r size and its relat ive hazard increase d with increasing size of the tumors, regardless ofwhether total or d isease-specific mort alit y was conside red. Using mul tivariate-analysiscon ducted Cox's proport ional hazards model, elevated S-phase rate, increased age, and presence of a sarcoma remained statistically significant risk factors. The prognostic value of DNA ploid y and lymph node status varied dependi ng on cho ice of end point. The study of tum or growth patt ern and tum or size pro vided no prognostic in formati on in the multi var iate analysis. Flow eytometrie cell analysis, including S-phase rate and DNA ploid y, is of va lue in predicting the prognosis of canine ma mma ry tumors and can be used as a new prognostic tool to improve the preoperative diagnostics of canine mamm ary tumors