Piroxicam and Bladder Cancer in Canines
Dear OncoLink "Ask The Experts,"
Is there anything new related to the diagnosis and treatment for canine bladder cancer (transitional cell cancer, or TCC)? Our vet recommends surgery, then Piroxicam. After reading what I can find on the Web, I am reluctant to go the surgery route and have started her on Piroxicam instead. I read about a urine test by Abbott Labs which uses a urine sample to test for TCC. Do you know whether this would give us a diagnosis without going through surgery to get a tissue biopsy?
Lili Duda, VMD, Section Editor of the OncoLink Veterinary Oncology Menu, responds:
Bladder tumors tend to occur in older female dogs, and certain breeds such as West Highland White Terriers and Scottish Terriers might be predisposed. The majority of bladder tumors are carcinomas, and the majority of these are transitional cell carcinomas. Affected dogs usually have symptoms such as blood in the urine, straining to urinate, and increased frequency of urination. Many affected dogs have secondary urinary tract infections.
Diagnosis is best achieved with a biopsy sample. This sample can be obtained surgically (through a procedure called a cystotomy) or by using a cystoscope. A cystoscope is either a rigid or flexible tube that can be passed into the bladder through the urethra and through which pictures of the tumor and small pieces of tissue can be obtained. Alternatively, fine needle aspirates obtained through the body wall using ultrasound guidance can be submitted for a cytological diagnosis.
In some cases, a diagnosis can be obtained through a cytological evaluation of a urine sample, since cancer cells are sometimes shed into the urine in enough numbers to allow for a diagnosis. However, this can be difficult if there is a large amount of blood, inflammation, and/or bacteria in the urine. Similarly, there is a "bladder tumor antigen test" that detects a molecular complex (a glycoprotein antigen) produced by bladder tumors. However, this test is unreliable if there is a lot of blood or inflammatory cells in the urine. In these cases, the result can be a "false positive", meaning that the test suggests the presence of cancer when no cancer is in fact present. On the other hand, if the test is negative, it is relatively unlikely (although still possible) that a bladder carcinoma is present.
Treatment for most bladder tumors is palliative, which means it is directed at minimizing symptoms and prolonging a good quality of life. Bladder tumors are usually large and invasive at the time of diagnosis, and even when there appears to be a solitary lesion that might be amenable to surgery, postoperative recurrence is very common.
Piroxicam is a non-steroidal anti-inflammatory drug (also known as an NSAID) that has offered benefit both in alleviating symptoms due to inflammation in many dogs, as well as causing actual tumor shrinkage in some dogs. Some recently published papers in the veterinary literature suggest that combining either mitoxantrone or carboplatin chemotherapy with piroxicam might provide additional benefit. The average survival times range from about 6 to 12 months.