膀胱癌-Bladder Cancer

What is the bladder?

The bladder is part of the urinary tract. It is at the bottom of the abdomen. It fills with urine and we pass urine out from time to time through a tube called the urethra. The urethra passes through the prostate gland and penis in men. The urethra is shorter in women and opens just above the vagina.

Urine is made in the kidneys and contains water and waste materials. A tube called a ureter comes from each kidney and drains the urine down to the bladder.

The cells that line the inside of the bladder are called transitional cells or urothelial cells. There is a thin layer of cells beneath the lining called the lamina propria. The outer part of the bladder wall contains a thick layer of muscle tissue which contracts from time to time to push out the urine.

What is cancer?

Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply 'out of control'.

A malignant tumour is a 'lump' or 'growth' of tissue made up from cancer cells which continue to multiply. Malignant tumours invade into nearby tissues and organs which can cause damage.

Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form 'secondary' tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.

Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), some have a better outlook (prognosis) than others.

So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook.

See separate leaflet called 'What are Cancer and Tumours' for further details about cancer in general.

What is bladder cancer?

Bladder cancer is a common cancer in the UK. It is about three times as common in men than women. In most cases in the UK, the bladder cancer develops from the transitional cells which line the bladder. This type of cancer is called 'transitional cell bladder cancer'. (Other types of bladder cancer are rare in the UK and are not dealt with further in this leaflet.)

Transitional cell bladder cancer is divided into two groups:

• Superficial tumours. These occur in about 4 in 5 cases. These tumours are confined to the inner lining, or just below the lining, of the bladder. Sometimes the cells which form this type of cancer multiply to form little 'warts' which stick out from the lining of the bladder.
• Muscle invasive tumours. These occur in about 1 in 5 cases. These tumours have spread to the muscle layer of the bladder, or right through the wall of the bladder.

The treatment and outlook for each of these two types are very different. Superficial tumours rarely spread and can usually be cured. However, if left untreated in some cases they can develop into muscle invasive tumours. Muscle invasive tumours have a high chance of spreading to other parts of the body (metastasise), and treatment has less chance of being curative.

What causes bladder cancer?

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply 'out of control'. (See separate leaflet called 'What Causes Cancer' for more details.)

Many people develop bladder cancer for no apparent reason. However, certain risk factors increase the chance that bladder cancer may develop. These include:

• Smoking. Bladder cancer is four times more common in smokers than non-smokers. Some of the chemicals from tobacco get into the body and are passed out in urine. These chemicals in the urine may be carcinogenic (damaging) to the bladder cells. It is estimated that about one third of bladder cancers are related to smoking.
• Other chemicals. Certain work-place and environmental chemicals have been linked to bladder cancer. Many of these chemicals are now banned in the UK. However, bladder cancer may develop as late as 10-25 years after exposure to certain chemicals. So, some cases are still being diagnosed in people who worked with these chemicals years ago.
• Schistosomiasis. This is a bladder infection which is caused by a parasite in certain hot countries.
• Repeated bouts of other types of bladder infection may also slightly increase the risk.

What are the symptoms of bladder cancer?

Blood in urine
In most cases, the first symptom is to pass blood in the urine ('haematuria'). Haematuria caused by an early bladder tumour is usually painless. You should always see your doctor if you pass blood in your urine. The blood in the urine may 'come and go' as the tumour bleeds from time to time.

Other symptoms
Some tumours may cause irritation of the bladder and cause symptoms similar to a urine infection such as going to the toilet frequently or pain on passing urine. If the cancer is a muscle invasive type, and grows through the wall of the bladder, then other symptoms may develop over time. For example, pain in the lower abdomen.

If the cancer spreads to other parts of the body, various other symptoms can develop.

How is bladder cancer diagnosed and assessed?

To confirm the diagnosis
The most important test to confirm a bladder tumour is called cystoscopy. A cystoscopy is where a bladder specialist (urologist) looks into the bladder with a special thin telescope called a cystoscope. The cystoscope is passed into the bladder via the urethra. A cystoscopy which is done to just look into the bladder is normally done under local anaesthetic. If a procedure is done via a cystoscope such as removing a tumour then a general anaesthetic is usually used. (See separate leaflet called 'Cystoscopy' for more details.)

During cystoscopy a urologist can

• See any areas on the lining of the bladder which look abnormal.
• Take a biopsy of suspicious area. A biopsy is when a small sample of tissue is removed from a part of the body. The sample is then examined under the microscope to look for abnormal cells.
• Remove a superficial tumour with instruments which can be passed down a side channel of the cystoscope.

Sometimes other tests are used to detect a bladder cancer. For example:

• A urine sample can be looked at under the microscope to see if any cancerous cells are present. Also, the urine can be checked for certain chemicals which may have come from a bladder tumour.
• Intravenous urography (IVU). This is an x-ray test to obtain pictures of your urinary tract. (See separate leaflet for details.)

Assessing the extent and spread
If the cystoscopy and biopsy confirm that the cancer is a superficial tumour then no further tests may be necessary. Superficial bladder tumours have a low risk of spread to other parts of the body.

However, if you have a muscle invasive tumour, then further tests may be advised to assess if the cancer has spread. For example, a CT scan, an MRI scan, or other tests. (There are separate leaflets which describe each of these tests in more detail.) This assessment is called 'staging' of the cancer. The aim of staging is to find out:

• How much the tumour in the bladder has grown, and whether it has grown to the edge, or through the outer part of the bladder wall.
• Whether the cancer has spread to local lymph nodes.
• Whether the cancer has spread to other areas of the body (metastasised).

By finding out the stage of the cancer it helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). See separate leaflet called 'Cancer Staging' for details.

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