Kidney Cancer in Cats

Last Modified: February 12, 2006

Dear OncoLink "Ask The Experts,"

My 12.5-year-old cat was just diagnosed with cancer in his right kidney. Apparently there is a tumor, and the kidney biopsy showed that the kidney tissue was dying. What is the best next step to take? We were told it was carcinoma. Does Prednisone help at all? I have read a lot about that medication.

Lili Duda, VMD, Section Editor of the OncoLink Veterinary Oncology Menu, responds:

Renal (kidney) tumors in cats, apart from lymphoma, are very rare, and there are only scattered case reports in the literature. Therefore, any treatment recommendations are based on educated assumptions, extrapolated from general veterinary oncology principles.

The first step in approaching kidney tumors is to get a biopsy sample and histopathological diagnosis. Renal cell carcinoma is the second most common tumor type reported, after lymphoma. A complete staging evaluation, including chest radiographs (X-rays) and an abdominal ultrasound, along with routine complete blood cell count, blood chemistry analysis, and urinalysis, should be performed. If there is evidence of metastasis (cancer spread to other areas of the body), the prognosis is poor. The role of chemotherapy is unknown in these tumors, and the best option might be simple supportive care. If there is no evidence of cancer spread, and the cancer appears to be confined to the kidney, surgical removal should be considered. However, particularly in older cats, it is important to ensure that the unaffected kidney has adequate function (through specialized radiographic tests, for instance) prior to removing the affected kidney. In addition, even if no evidence of metastasis is detected at the time of surgery, metastasis might become apparent within the weeks or months following surgery. The metastatic rate of this tumor in cats is unknown. In dogs, renal carcinoma has a very high rate of metastasis, but there is some minimal evidence that it may be less metastatic in cats.

While prednisone plays a role in the chemotherapeutic treatment of lymphoma, it has no anti-cancer activity for carcinoma by itself. However, prednisone is also a potent anti-inflammatory, and thus may have a role in supportive care of selected patients.