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Transitional
Cell Carcinomas in Dogs
Dr.
Gail Mason, DVM, MA, DACVIM
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 know cure of 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 patientŐs 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.
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