Page 389 - WSAVA2017
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WSVA7-0340
MEDICAL ONCOLOGY
BLADDER TUMORS: LATEST INFORMATION
S. Ettinger1
1DR SUE CANCER VET PLLC, Oncology, TARRYTOWN, USA
BLADDER TUMORS: LATEST INFORMATION Sue Ettinger, DVM, DACVIM (Oncology)
Dr Sue Cancer Vet PLLC and Animal Specialty & Emergency Center Wappinger Falls, NY, USA
drsuecancervet@gmail.com Key Points:
• The majority of lower urinary tract tumors are malignant, with transitional cell carcinoma (TCC) the most common.
• If bladder cancer is suspected, urine should not be collected via cystocentesis, since the procedure can cause seeding and transplant tumor to unaffected abdominal sites. Percutaneous aspirates and biopsies should also be avoided.
• Since the trigone lesion is most common, complete surgical excision is unlikely.
• Medical management is the mainstay for TCC therapy. Mitoxantrone and NSAID therapy is well tolerated
and can cause reduction is tumor size, palliation and improvement of clinical signs, and increased survival times.
Lower urinary tract tumors are relatively rare in dogs, estimated to be less than 2% of reported tumors. The most common malignancy is transitional cell carcinoma (TCC), which is most commonly located in the trigone area. Fifty percent of dogs will have uretheral involvement from extension of the primary bladder mass.
TCC is usually highly invasive in dogs. Problems associated include clinical signs of lower urinary
tract disease with is troubling to dogs and owners.
The cancer can lead to urinary tract obstruction and distant metastases in >50% of dogs. Risk factors include exposure to older flea control product and lawn chemicals, obesity, female sex, and a very strong breed associated risk. A 2013 study demonstrated that dogs could be exposed to chemicals through contact with their own lawn (treated or contaminated by drift) or through contact with other grassy areas if they travel. Clients should be aware that neighbor’s lawn chemicals can contaminate their property. Feeding vegetables may help prevent TCC.
The Veterinary Bladder Tumor Antigen test (VBTA) is 85% sensitive for TCC but only 45% specific in the presence
of other urinary tract disease (hematuria, pyuria). It can be used as a screening test and a negative result in 85% reliable but a positive result does NOT equal TCC.
In general surgery is considered palliative because of
the high metastatic rates and because normal tissue often contains neoplastic or pre-neoplastic tissue. Visual assessment at the time of cystectomy is often inaccurate for achieving tumor-free margins. Wide surgical excision is imperative. Even with complete resections, TCC recurrence is likely, either due to microscopic cells at
the margins or development of de novo tumors. Surgery reduces clinical signs but may not extend survival.
Medical management is the mainstay for TCC therapy. Although TCC is typically not curable, treatment is
often well-tolerated so treated dogs live longer AND live well. Approximately 75% of dogs respond favorable to treatment and can enjoy several months to a year or more of good quality life.
Several drug combinations and protocols have been evaluated. The most commonly used protocol is mitoxantrone and piroxicam. Overall response rate
is 35% with a MST of 350 days. 75% of the 49 dogs had clinical improvement even if the tumor did not have measurable remission. Gastrointestinal and renal toxicity was low and reported at <15%. In contrast, the MST with piroxicam alone is approximately 6 to 7 months, and the MST with surgery alone is approximately 3.5 months.
Cisplatin has also been evaluated with NSAIDs, but this protocol is not recommended. Cisplatin can be nephrotoxic, and NSAIDs can exacerbate renal toxicity.
Additional research has evaluated newer NSAIDs that are more COX-2 selective. In 2011, deracoxib (Deramaxx), a selective cyclooxygenase-2 inhibitor, was evaluated
in 26 dogs with bladder TCC. Dogs were treated PO with deracoxib at a dosage of 3 mg/kg/d as a single- agent treatment for TCC. Tumor response was assessed via radiography, abdominal ultrasonography, and ultrasonographic mapping of urinary bladder masses.
Of 24 dogs for which tumor response was assessed, 4 (17%) had partial remission, 17 (71%) had stable disease, and 3 (13%) had progressive disease; initial response could not be assessed in 2 of 26 dogs. The median survival time was 323 days. Median
time to progressive disease was 133 days. Renal, hepatic, and gastrointestinal abnormalities attributed
to deracoxib administration were noted in 4% (1/26), 4% (1/26), and 19% (5/26) of dogs, respectively. Results indicated that deracoxib was generally well tolerated
by dogs and had antitumor activity against TCC. Firocoxib (Previcox) has also been evaluated.
An Urban Experience
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