FELINE MAMMARY TUMORS: TREATMENT NOW IN THE FUTURE

摘要

The saying that "Cats are not small dogs" has many truths, and when it comes to certain tumor histologies, the biologic differences between these two popular and favorite companion animal species can be very divergent. Such is the case with tumors ofthe mammary gland. In dogs, approximately 25% of mammary tumors are considered malignant and possess the capacity to metastasize. However, this is not the case with cats, as the vast majority of mammary neoplasms are aggressive and metastatic (>90%). Unfortunately, not only are feline mammary tumors biologically aggressive, but they occur with some degree of frequency, too, accounting for 10.3-12% of all diagnosed tumors in the cat. There is a definite gender predilection for the development of mammarytumors, as female cats are more frequently affected than males, with queens developing mammary tumors at an incidence of 25.4/100,000. Regardless of gender, mammary tumors most commonly arise in older cats (average 10-12 years) and most are histologically classified as adenocarcinomas. Poor prognostic indicators in cats with mammary gland carcinomas include high grade tumors, lymphatic or vascular invasion, tumor size greater than a three centimeter diameter and neoplastic cell staining for vascular endothelial growth factor (VEGF). Overall, given their aggressive biologic behavior and rapid rate of distant metastases, the median survival of these cats clinically manifesting with poor prognostic indicators is quite short, approximately four to nine months. However, all hope should not be lost for these feline patients, as the early detection of disease with the prompt institution of appropriate therapy can often provide survival times in the range of 24 months. Although traditional therapies do provide some benefit, both in quality-of-life and survival time, newer treatment options are necessary.