Bladder cancer refers to the growth of a tumor within the lining of the bladder. In some cases, the tumor can invade surrounding tissue and spread to other parts of the body. The most common symptom of bladder cancer is blood in the urine and this should be investigated by a doctor.
Normal urinary bladder
The bladder is a hollow, balloon-like organ located in the pelvis that stores urine before it is excreted from the body. Urine produced in the kidneys is passed into the bladder via tubes called the ureters, which enter the bladder from either side. When the bladder is full, muscles in the bladder contract to push urine out of the body via a tube called the urethra.
Types of bladder cancer
One of the most common types of bladder cancer is transitional cell or urothelial carcinoma, which makes up about 90% of bladder cancers. These carcinomas resemble the urothelial cells that normally line the inner walls of the bladder. Urothelial cells are also found lining other parts of the urinary tract such as the ureters, urethra and parts of the kidneys. Transitional cell carcinomas can also affect these areas.
Bladder tumors can be divided into non-invasive cancers, which are still confined to the bladder lining, and invasive cancers that have penetrated the lamina propria or grown even deeper into the muscle layers of the bladder.
Transitional cell carcinomas are also divided into two subtypes:
Papillary carcinomas – These are finger-like processes that extend from the inner surface of the bladder towards the centre. These are referred to as non-invasive papillary cancers, unless they grow into layers beyond the inner layer of bladder cells. If this occurs, the tumor is considered an invasive transitional cell carcinoma.
Flat carcinomas – These growths stay flat against the lining of the bladder and do not grow towards its centre. If the flat tumor is confined to the inner layer of bladder cells, it is classed as a non-invasive carcinoma. If the tumor grows into the deeper layers of the bladder, however, it becomes an invasive transitional cell carcinoma.
Risk factors associated with bladder cancer
Some factors raise the risk of getting bladder cancer. Some of these risk factors are modifiable, such as smoking, while factors such as a family history of the condition are not modifiable. Some examples of the risk factors for developing bladder cancer include smoking, exposure to harmful chemicals (such as aromatase amines in dyes), older age, chronic bladder irritation, being female, and family history of the condition.
To diagnose bladder cancer, a doctor tries to establish whether there are any risk factors for the condition. A physical examination of the rectum and vagina may be carried out to check for lumps and a urine sample arranged to test for infection or abnormal cells. If bladder cancer is suspected, a patient is referred for further tests such as cystoscopy, biopsy and a computed tomography (CT) scan.
In cases of non-muscle invasive bladder cancer, the cancerous tissue can usually be removed while leaving the remainder of the bladder in tact. This is achieved using a technique called transurethral resection of a bladder tumor (TURBT), which may be followed by a dose of chemotherapy administered to the bladder to help prevent recurrence of the cancer.
In cases of muscle-invasive bladder cancer, the whole bladder is usually removed in a process called radical cystectomy. If surgery is not possible, radiotherapy and chemotherapy may be advised.
Those with non-muscle invasive bladder cancer usually survive for at least 5 years after diagnosis (in 80% to 90% of cases). However, recurrence rates are high, with a more invasive form of the cancer returning in around 10% of cases. Those with muscle-invasive bladder cancer have less chance of surviving for five years after diagnosis.
Bladder cancer statistics
Bladder cancer usually occurs in people aged over 55 years and the average age at diagnosis is 73 years. Bladder cancer is the fourth most common cancer diagnosed in men and is four times more common among men than among women.
Overall, the chance that a man will develop bladder cancer during his lifetime is about 1 in 26, whereas for women, the chance is about 1 in 90. However, women who do develop the condition tend to have a worse outcome, since they are more prone to developing the muscle-invasive form of bladder cancer. White people are diagnosed with bladder cancer almost twice as often as black people are.
Reviewed by Sally Robertson, BSc