Transitional Cell Sarcomas in Dogs

By Dr. Gail Mason, DVM, MA, DACVIM and Kathi Smith, RVT, Internal Medicine & Oncology Technician

Primary cancer of the bladder in dogs is relatively uncommon. Of those occurring in that location, transitional cell carcinoma (TCC) accounts for 50-80% of all reported cases.

Diagnosis of Transitional Cell Carcinomas
The clinical signs of bladder cancer in dogs are generally similar to those of urinary tract infections (cystitis) and urinary stones (cystic calculi). For this reason diagnosis by cytology of biopsy is required. Tests used in diagnosing TCC include:

• Urinalysis
• Cytology (urine or tissue aspirate)
• ultrasonography (+/- guided needle biopsy)
• abdominal radiographs (x-rays)
• routine bloodwork
• cystoscopy (fiberoptic exam of bladder/urethra)

Treatment for TCC
The overall metastatic rate for TCC is approximately 50%, and unfortunately, at this time there is no known cure for this disease. Control of local disease and its clinical signs are the main goal of therapy.

Surgery for TCC
Surgery can be a viable option for TCC patients but often the extent and tumor location provide multiple challenges. Surgery is generally considered palliative (vs. curative) for this tumor and may include:
• partial bladder removal (cystectomy)
• urinary tract diversion (catheter placement)
• bladder reconstruction

The risks and benefits expected with surgical treatment of TCC are worthy of a detailed discussion with a veterinary surgical specialist to determine if it is a reasonable option for a particular patient.

Chemotherapy for TCC
Systemic chemotherapy for bladder or urethral TCC has produced varying results. Drugs that have been employed include:
• Doxorubicin
• Mitoxantrone
• Cisplatin
• Cyclophosphamide

Though these drugs are relatively well tolerated in animals, most all reported survival times of less than one year. A recent retrospect study of 25 dogs with inoperable urinary bladder carcinoma suggested a survival advantage might exist when dogs receive doxorubicin (or mitoxantrone) in addition to a platinum-based compound (cisplatin or carboplatin). Similar combinations warrant further investigation. The drugs do, however, frequently abate the patientÕs symptoms.

Piroxicam
Interestingly, though not anticancer drugs per se, piroxicam and other non-steroidal anti-inflammatory drugs (deracoxib, metacam) have shown activity against TCC in dogs. They can be used alone or in combination with chemotherapeutic agents.

Anti-inflammatory drugs can exert antitumor activity by several mechanisms. They appear to include reduction of swelling, pain, formation of new blood vessels in tumor tissue, and perhaps direct antitumor effects on malignant cells.

Piroxicam can be extremely useful in the management of TCC in dogs. It works rapidly to reduce tumor swelling and obstruction to urine outflow. As a single agent, it is known to control TCC for at least as long as multiple-drug protocols.

These drugs can be used safely in many dogs and cats. However, adverse reactions in the gastrointestinal tract (gastritis, vomiting, bleeding ulcers) and in renal (kidney) function have been reported. If your pet is taking such a drug, monitor him/her for signs of decreased appetite, vomiting, or dark black stools, which may necessitate drug withdrawal.

Prognosis
Early diagnosis and intervention in patients with TCC are likely to produce the most favorable prognosis. Currently, recommended combination therapy with surgery, anti-inflammatory agents, and chemotherapeutics offer the best chance of tumor control. The long-term prognosis still remains guarded to poor as remission times uncommonly exceed 1 year. However, remission time can be good quality time for both pet and owner.