Apoptosis in Mammary Carcinoma: Not a Survival Indicator

Mammary tumors are the third most common type of neoplasia in female cats. They are usually malignant and progress rapidly. Grading mammary tumors is useful in predicting postsurgical outcome. A recent study in human medicine shows a positive correlation between cell proliferation or tumor grade and apoptosis. This study was conducted to evaluate the role of apoptosis in feline mammary tumors and its relationship with invasiveness and cell proliferation assessed by mitotic index. Thirty-tree tissue samples from cats with malignant primary mammary tumors were evaluated. The neoplasias included several types of carcinoma. Thoracic radiographs and ultrasonograms of the spleen, liver, and kidneys were taken before surgery and every 2 months over a 2-year period. Follow-up was for 2 years or until death due to the tumor.

Three of the cats were graded stage 0 and were alive after 24 months. The 12 cats graded as stage I had a survival time of 21.83 (± 7.83) months. The cats in stage II had a survival time of 13.38 (± 8.99) months. A close correlation was found between the growth fraction expressed by the mitotic index and the infiltrative growth graded as the histologic stage. The apoptotic index in cats showed no correlation with histologic invasiveness or clinical outcome.

Although the apoptotic index was not useful in predicting outcome in cats, this study confirmed the value of histologic grading in predicting postsurgical outcome of cats with mammary tumors.

Rate of apoptosis in feline mammary tumors is not predictive of postsurgical survival. Giuseppe S, Preziosi R, Benazzi C, et al. J VET DIAGN INVEST 15:115-122, 2003.