Transitional Cell Carcinoma of the Lower Urinary Tract in Dogs
What is Transitional Cell Carcinoma?
Transitional cell carcinoma is the most common tumor of the canine lower urinary tract. Scottish Terriers are predisposed to developing this cancer. Transitional cell carcinomas is locally invasive, extending into underlying normal tissues, and has a moderate-high rate of spread to other places in the body (called metastasis).
Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:
- Complete blood count (CBC)
- Serum biochemistry panel
- Urinalysis (U/A)
- Thoracic radiographs
- Abdominal sonogram
- +/- Contrast urethrocystogram
Tumors are often located in the trigone area where complete surgical removal is not possible (our surgeons are trying newer more aggressive surgeries that may be an option for some dogs). We have occasionally used definitive radiation therapy to treat transitional cell carcinoma, and if a tumor is small and localized this may be something to consider, although the efficacy of radiation therapy is diminished when used to treat bulky disease. Radiation therapy consists of 19 treatments given on a Mon-Fri schedule. Because of the inability to perform complete surgical removal and the limitations of radiation therapy, treatment often consists solely of chemotherapy. Cisplatin, carboplatin, doxorubicin and mitoxantrone all have reported activity with response rates of approximately 30-35%. In our hospital, chemotherapy is administered with a single drug given at 3-week intervals and the tumor reassessed at 6-week intervals. If/when tumor progression is noted, treatment can be changed to an alternate agent. Chemotherapy drugs work by targeting fast-growing cells; cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people. We do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what to watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.
We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as anti-tumor activity against transitional cell carcinoma. This medication should be given with food and the pet owner instructed to watch for signs of gastrointestinal upset (vomiting, change in stool, etc.). If such signs develop, piroxicam should be discontinued for 3-5 days. Restarting of therapy can then be considered in conjunction with the stomach-protectant misoprostil.
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