As in dogs, tumor size is an important prognostic factor, although for tumors less than three centimeters the individual size is less predictive. According to one study, cats with tumors less than three cm had an average survival time of 21 months, and cats with tumors greater than three cm had an average survival of 12 months. About 10 percent of cat mammary tumors have estrogen receptors, so spaying at the time of surgery has little effect on recurrence or survival time.
Tumor size, a prognostic factor in dogs, is less predictive for tumors smaller than three centimeters.  In cats, tumor size influences survival time; those under three cm have an average of 21 months, while larger ones have 12 months. Estrogen receptor presence in about 10% of cat mammary tumors has little impact on recurrence or survival time after spaying.