Bladder cancer in cats and dogs.

Bladder Cancer in Cats and Dogs

What are bladder tumors?
Bladder is the organ that collects urine excreted by the kidneys prior to disposal by urination. The most common type of
bladder cancer is called transitional cell carcinoma (TCC), which arises from the epithelial cells that line the bladder.
However, other less frequently observed types of bladder exist such as squamous cell carcinoma, adenocarcinoma,
undifferentiated carcinoma, rhabdomyosarcoma, fibroma, and other mesenchymal tumors. In dogs, this tumor invades
into the deeper layers of the bladder wall including the muscle layers. As the tumor grows bigger, it can cause
obstruction to the flow of urine from the kidneys to the bladder or from the bladder to the outside of the body. TCC in
dogs also has the ability to spread to lymph nodes and to other organs in the body such as the lung or liver.To review a
comprehensive information prepared by the Purdue University School of Veterinary Medicine about canine TCC, click
here.

Source: www.animalhelp.com/images/articles/malecatreprosys3.jpg (cat)
www.allergicpet.com/articles/dog_bladder_stones.jpg (dog)

How common are these tumors?
Bladder cancer is not very common, It accounts for approximately 2% of all reported cancers in the dogs and rarely
reported in cats. The exact cause of TCC is usually not known but in general, canine TCC results from a combination of
several factors including genetic predisposition and environmental factors. A genetic predisposition is suspected
because TCC is more common in specific breeds of dogs, including Scottish Terriers (18 fold increased risk compared
to other breeds), Shetland Sheepdogs (4 fold increased risk), Beagles (4 fold increased risk), West Highland White
Terriers (3 fold increased risk), and Wire Hair Fox Terriers (3 fold increased risk). Environmental factors identified as
risk factors in previous studies have included pesticides, insecticides and "old generation" flea dips. One of the cause
of TCC in humans is smoking but the extent to which second hand smoke may contribute to TCC in dogs is not known
at this time.

What are the symptoms?
The most frequent symptoms of TCC are blood in the urine, painful urination, frequent urination and/or straining to
urinate. These symptoms overlap with those common in urinary tract infection, therefore, these symptoms alone do not
necessarily mean that the pet has TCC. If the tumor has spread to other organs such as the bones or the lungs, the
pets may show lameness and a paraneoplastic syndrome called hypertrophic osteopathy.

How is the diagnosis made?
Bloody urine accompanied by difficulty to urinate could be caused by a variety of medical conditions other than cancer
such as bladder infection, bladder stones, or bladder inflammation. The veterinarian will, therefore, have to first conduct
a series of steps to rule out these common conditions. These tests include complete blood count (CBC), serum
biochemistry profile, urinalysis, urine culture, X-rays of the abdomen and chest, and bladder imaging (eg cystography
or cystosonography). Some of these conditions can also produce "masses" to be seen on radiographs or ultrasound,
and some can cause abnormal cells in the urine, which can be mistaken for TCC. Therefore, the definitive diagnosis of
TCC will require a tissue biopsy and subsequent examination of the cells under the microscope. This is important
because the treatment and prognosis depend entirely on exactly what is wrong with the bladder. A tissue biopsy can be
obtained by surgery, cystoscopy (insertion of a fiberoptic scope into the bladder and biopsy through the scope), or in
some cases with a urinary catheter.

What evaluation is needed for a pet with TCC?
Once a diagnosis of TCC is made, it is important to determine the stage (extent) of the disease so that the oncologist
can determine the best way to treat the cancer, to gain some information about the pet's prognosis, and to establish a
baseline tumor measurement in order to determine if treatment is successful. The staging process typically looks at
three factors: the primary tumor, spread to lymph nodes, and spread to distant organs. Tumor staging for TCC includes
chest X-rays to look for lung metastasis, abdominal X-rays and ultrasound (or CT scan) to look for metastasis in the
abdomen and to assess any changes in the kidneys, and imaging of the bladder to determine the exact location and
size of the tumor. These tests are repeated during treatment to know if the treatment is being effective.

Do these tumors cause pain?
It is imperative that pets with cancer are provided with pain medication to relieve discomfort caused by the disease as
well as by the treatments. To learn more, please visit the Cancer Pain Management section.

What food should be fed to pets with cancer?
Pets with cancer need to be fed diets specifically designed to support a cancer patient. To learn more, please visit the
Cancer Nutrition section.

What are the treatment options?
Because most canine TCCs are invasive into the bladder wall and located in the neck of the bladder where several vital
structures are located, surgical removal is usually not possible. It has not yet been completely determined what benefit
would occur from removing part of the tumor in dogs in which the entire tumor cannot be removed. If surgery is not
possible, radiation therapy can be used to control the growth of TCC, however, its associated complications, including a
scarred, shrunken bladder, and irritation to surrounding organs, largely limit its clinical benefit. The majority of TCC
cases are treated with 2 types of medications: traditional chemotherapy (eg cisplatin, carboplatin, adriamycin) and
nonsteroidal antiinflammatory drug (NSAID) called piroxicam. The response to chemotherapy alone has been rather
disappointing and oncologists at Purdue University Veterinary School of Medicine became interested in piroxicam when
unexpected remissions were noted in dogs in whom the drug was used for pain relief. This has led to numerous studies
of piroxicam in animals with cancer at Purdue. In 62 dogs with TCC treated with piroxicam, the tumor went into complete
remission in 2 dogs, decreased in size (by > 50%) in 9 dogs, remained "stable" in size (<50% change) in 35 dogs, and
increased in size (by > 50%) in 16 dogs. The median survival (195 days) compared favorably to survival with
chemotherapy in other studies. In an attempt to improve the response of TCC to therapy, oncologists at Purdue
University conducted a study comparing chemotherapy (cisplatin) alone to chemotherapy plus piroxicam. In this study
the combination of cisplatin and piroxicam was more effective against the cancer, but the combination treatment caused
a rise in the urea level in a blood test, indicating that the combined treatment affected kidney function. Combining
piroxicam with other chemotherapies has not been as successful. Currently, oncologists at Purdue University are
conducting a study of cisplatin chemotherapy combined with a new NSAID drug to evaluate if tumor remission can occur
with less toxicity. Recently, concerns have been published regarding a potentially small increase in risk for heart attack
and stroke in people receiving this new drug but because dogs do not develop disease in their blood vessels like
humans do, the drug is not expected to produce similar side effects.

What are the treatment associated risks?
Drugs like piroxicam have few side effects but in some dogs (less than 20%), piroxicam will irritate the stomach or
intestine. Therefore, if a dog on piroxicam has loss of appetite, vomiting, or dark tarry-looking stools, it is safest to stop
the piroxicam and consult the veterinarian before starting the medication again.

What is the prognosis?
Survival is affected by the growth rate of the tumor, the exact location of the tumor within the bladder, and whether the
tumor has spread to other organs or not. Unfortunately, most dogs with TCC will eventually succumb to the disease but
many will enjoy several months or longer with a good quality of life. The median survival in dogs treated with
chemotherapy (cisplatin or carboplatin) at Purdue University was 130 days. Median survival with piroxicam treatment in
62 dogs with TCC was 195 days. The survival times in all of these studies, however, varied tremendously from dog to
dog. Some dogs have died after only a few days, while others have lived more than two years. Factors that have been
identified in Purdue University studies that negatively affect survival time include more extensive tumor within the
bladder, spread of tumor beyond the bladder, and involvement of the tumor in the prostate gland. Regarding
metastasis of TCC in dogs, approximately 20% of dogs with TCC have detectable metastasis at diagnosis, and 50%
have metastasis at death. Longer survival times have been reached when chemotherapy is combined with piroxicam,
but the optimal combination treatment is still being determined.

Are there any clinical trials for TCC?
There are available clinical trials, please click here to get more details.

Additional online resources about bladder cancer in pets

Sources:

www.vet.purdue.edu/pcop/CanineUrinaryBladderCancer.pdf
Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins,
1998.