TRANSITIONAL CELL CARCINOMA
The transitional cell carcinoma (frequently abbreviated "TCC") is a particularly unpleasant tumor of the urinary bladder. In dogs, it usually arises in the lower neck of the bladder, where it is virtually impossible to surgically remove, and causes a partial or complete obstruction to urination. The urethra (which carries urine outside the body) is affected in over half the patients diagnosed with transitional cell carcinoma; the prostate gland of male animals may also be involved and the tumor can spread to distant sites (other body areas) in approximately 50% of cases. In cats, the site of the tumor within the bladder is more variable. Bloody urine and straining to urinate are typically the signs noted by the owner.
WHY IS THIS TUMOR CALLED A “TRANSITIONAL CELL” CARCINOMA? IS SOMETHING IN TRANSITION?
While bladder tumors are somewhat rare as types of cancers go in pets,
WHAT CAUSES THIS TUMOR?
As with most cancers, we do not know many specific causes. Presumably, repeated exposure to carcinogens in the urine is an important cause. We know that chemotherapy with cyclophosphamide is a cause. We know that female dogs tend to get more transitional cell carcinomas than male dogs (possibly because females do less urine marking and are thus possibly storing urinary toxins longer). In cats, however, males have an increased risk over females. Urban dwelling and obesity have been found to increase the risk for the development of this tumor. We know that Shetland sheepdogs, West Highland White terriers, Beagles, and Scottish terriers seem to be predisposed breeds. Beyond this, specifics remain unknown.
The average age at diagnosis in the dog is 11 years.
WHAT KIND OF TESTING IS NEEDED TO IDENTIFY THIS TUMOR?
Bloody urine with straining can be caused by many other conditions besides cancer. A severe bladder infection, a bladder stone, or Feline Lower Urinary Tract Disease would be far more common and must be explored first. In other words, reaching a diagnosis is a step-by-step procedure whereby the most common conditions are ruled out one by one until a diagnosis is confirmed.
First step: Urinalysis and culture. Many people are confused by the difference between these two tests. A urinalysis is an analysis of urine including the a brief chemical analysis and a microscopic examination of the cells contained in the sample. A culture involves plating a sample of urine sediment on growth medium, incubating for bacterial growth, identifying any bacteria grown, and determining the what antibiotics are going to be effective.
Urinalysis and culture will rule in the presence of a bladder infection. (The presence of documented infection absolutely does not rule out the presence of a tumor as tumors may easily become infected).
Second Step: If no infection is found, if the urinalysis is normal despite obvious symptoms, or if a growth is palpable, radiographs would be the next step. The goal at this point would be to rule out a bladder stone. Bladder tumors are not visible on plain radiographs though sometimes some bony proliferations grow on the pelvic bones in reaction to bladder tumors.
Third Step: At this point, special imaging methods are needed to see inside the urinary bladder. This can be done with contrast radiography, ultrasound, or cystoscopy.
With this technique, a combination of radiographic dye and air are injected into the bladder via a urinary catheter. This allows definition of structures within the bladder such as bladder stones which are “radiolucent” (i.e., do not show up on plain radiographs), polyps (benign growths in the bladder caused by chronic inflammation) or tumors. The procedure is simple and probably the least expensive of all three methods as most animal hospitals have the equipment to perform contrast radiography. The problem is that female animals are rather difficult to catheterize. If the patient is a female, ultrasound may be a better choice.
Ultrasound: Ultrasound uses sound waves to create an image of structures within the urinary bladder. This presents a non-invasive way to detect radiolucent stones, polyps, or tumors within the bladder. If a growth is found, it is tempting to sample the cells by needle aspirate; however, the TCC is famous for seeding other organs via needle track so it best not to attempt aspiration. Sampling is best done by cystoscopy (see below). Ultrasound is helpful in determining the extent of tumor spread after diagnosis has been confirmed (see below). Ultrasound is not available in all hospitals and sometimes referral is necessary.
Ultrasound image of a Transitional Cell Carcinoma in a dog's bladder neck.
Cystoscopy: With cystoscopy a tiny camera on a flexible thin rod is inserted into the urethra and the bladder can be visualized. Small biopsy instruments can travel up the channel to collect tissue samples. This equipment is highly specialized and is not available even at referral facilities in many areas.
The finding of a mass in the neck of the bladder
TRANSITIONAL CELL CARCINOMA HAS BEEN DIAGNOSED. NOW WHAT?
When your pet is diagnosed with cancer most people want to know how long their pet has to live and what treatments are available. Prognosis depends on the stage of the disease (i.e. whether the tumor is invading other local organs, whether there is evidence of lymph node spread, if there is evidence of distant tumor spread.)
In one study, median survival time was 118 days for dogs with evidence of
Dogs with no involvement of local lymph nodeshad a 234 day survival time
Dogs with evidence of distant tumor spread had a median survival time of
In one study of 20 cats with TCC, the median survival time was 261 days.
Ultrasound of the belly is needed to assess the involvement of local lymph nodes and whether or not other organs have been invaded. Radiographs of the chest are the usual way to screen for distant tumor spread; most tumors will spread to the lung leaving visible round opacities there.
WHAT ARE THE TREATMENT OPTIONS?
Any way you look at it, this transitional cell carcinoma is bad news. It is aggressively malignant and generally grows in an area not very amenable to surgical removal. If the tumor becomes so large and deeply invasive that the patient cannot urinate, an unpleasant death ensues in a matter of days.
Partial Removal of the Bladder
If the tumor is fairly small at the time it is detected (there is room enough for margins of 3 cm of normal bladder to be removed around the tumor), it may be worth attempting to remove it and this means removing part of the bladder. If one is very lucky, complete removal or very long term survival is possible. (In one study over half the patients were alive a year after surgery!) Problems with this therapy include: the fact that it is not possible to determine with the naked eye what the margins of the tumor actually are (so it is easy for the surgeon to believe they have removed enough tissue when in fact there is more tumor present), and reduced storage capacity of the remaining bladder after surgery leads to need to urinate more frequently. If recurrence happens it generally does so within one year of surgery and is thought to occur from either inadequate tumor removal during surgery or development of a new tumor via the same mechanism that led to the development of the original tumor. There is evidence that using a cyclooxyrgenase inhibiting anti-inflammatory medications (deracoxib, piroxicam) has activity against the TCC and can assist in prevention of recurrence.
Permanent Urinary Catheter
A permanently placed urinary catheter can be implanted in the patient’s urinary tract to create more comfortable urination. The placement of a foreign body in this way will predispose the patient to bladder infection and frequent screening cultures will be needed; still, in one study six out of seven owners reported satisfaction with results in their pets. Obviously, this procedure does nothing to actually hinder the growth of the tumor. Owners will need to empty the bladder with a drainage tube at least 3 times a day to avoid stagnation of urine. The entrance to the catheter must be kept clean and must be cleaned daily. Tube dislodgement is a serious complication. Newer tubes are made to be very short and a longer drainage tube is attached during bladder emptying. More traditional permanent catheters are longer and will require some sort of wrap or garment for protection. If a tube dislodges, it must be replaced by within 48 hours as scar tissue rapidly forms to close the opening into the bladder. Sedation is required for tube replacement; it is not something an owner can do at home.
In this procedure, a metal stent is placed in the urethra to allow the passage of urine through the tumor. This is a similar concept as the permanent catheter but more "high tech." The stent is placed either surgically or with a special video radiography called "fluoroscopy." The procedure is relatively simple and not invasive but does require special equipment. Urinary incontinence is unfortunately a common problem after this procedure and special garments/diapers may be needed indoors.
With this procedure the entire urinary bladder is removed. The kidneys (where urine is produced) normally deliver urine to the bladder for storage via tiny tubes called ureters. After the bladder is removed, the ureters are attached to the colon so that the patient effectively passes urine rectally along with stool. This is a very radical surgery and potential complications can include scarring of the ureters and loss of kidney function, infection, and blood biochemical abnormalities. Special diets are required after surgery as well as long term antibiotics, frequent blood test monitoring, and free access to an area for urination (pets will need to urinate approximately every 4 hours).
Laser Ablation with Chemotherapy
A study was published in the February 15th, 2006 issue of the Journal of the AVMA where 7 dogs with transitional cell carcinomas were treated with a combination of laser ablation, piroxicam (see below) and mitoxantrone (see below). Laser ablation is a treatment that has been used for many years in humans with urinary tract cancer. In short, a surgical laser is used to vaporize the tumor from the surface of the bladder and urethra. In the study above, the 8 dogs received this treatment followed by chemotherapy and their symptoms and survival were tracked. Median disease-free interval (i.e. the time without significant symptoms) was 200 days and median survival time was 299 days. These survival times were felt to be similar to those achieved with chemotherapy alone and no surgery at all; however, a more lasting resolution of symptoms was felt to have been achieved with this combination treatment. Please note, only 7 dogs were studied (an 8th received treatment but died after the first chemotherapy treatment from an automobile accident); information from a larger population would be helpful in solidfying these interpretations. This form of treatment is not without controversy at this time.
There are numerous protocols involving different combinations of cyclooxygenase inhibitors (Non-steroidal Anti-inflammatory drugs) and chemotherapy agents. It has been recommended that the tumor be re-staged every 6-8 weeks to determine if a revision in therapy is needed and, of course, complete staging should be done at the beginning to select the most appropriate treatment. If the tumor is found to be the same size or smaller when it is re-staged, then the protocol is deemed to be working and should be continued so long as there are no problems with unacceptable medication side effects.
This medication is a non-steroidal anti-inflammatory drug, previously used in the treatment of canine arthritis but largely abandoned for this use with the development of safer products. It is not clear if this medication works because of its anti-inflammatory effect or if it actually has anti-tumor effects, both therapeutically and preventively. This medication is inexpensive, given once a day (or less in the cat), available through most human pharmacies, and administered orally. Because of these qualities, it has become especially popular as a conservative therapy. Side effects include potential for stomach ulcers and effects on the kidney though these can be addressed with additional medications should they become problematic. In the 2003 study by Knapp, 62 dogs with TCC were treated with piroxicam alone. The median survival time was 195 days with 3% of dogs experiencing complete remission, 14% with partial remission, and 56% with no change in tumor size. These results are impressive considering no conventional chemotherapy was involved.
A combination of piroxicam and mitoxantrone has been studied and yielded a measureable response in 35% of patients. Approximately 18% had intestinal side effects and 10% had kidney related side effects. The median survival time was 350 days. For many oncologists, this protocol is the first choice in therapy. Daily oral piroxicam is used and intravenous mitoxantrone is given every 3 weeks for four treatments.
Special facilities are required to deliver radiation therapy so if one elects this sort of treatment some sort of travel is likely to be needed. Here, the patient is anesthetized, the bladder is surgically exposed and a radiation beam targets the tumor. In other techniques, the bladder is not surgically exposed and the radiation beam targets the tumor externally. It is not clear if one method produces better results. In most cases, surgery or chemotherapy is performed in conjunction with radiotherapy. Results have been variable with some very long survival times and some patients with short survival times. The urinary bladder tends to scar with exposure to radiation which leads to incontinence. More work is needed to develop a more clearly beneficial radiation therapy protocol for the treatment of bladder tumors.
For more detail on specific treatments, we recommend a consultation with an oncology specialist. To find an oncologist in your area, either ask your veterinarian to arrange a referral or use this link:
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Page last updated: 6/30/2017