What is bladder cancer?
Bladder cancer begins when cells in the inner lining of the bladder become abnormal, growing and dividing out of control.
One day I noticed some blood in my urine. I postponed going to the doctor – I talked myself into it being an infection.
The treatment path for bladder cancer depends on how far the cancer has spread into the layers of the bladder:
- Non-muscle-invasive tumours – The cancer cells are found only in the inner lining of the bladder (urothelium) or in the next layer of tissue (lamina propria) and haven’t grown into the deeper layers of the bladder wall. Most bladder cancers are non-muscle-invasive tumours. Learn more about treatment for non-muscle-invasive tumours.
- Muscle-invasive tumours – The cancer has spread beyond the urothelium and lamina propria into the layer of muscle, or right through the bladder wall. Learn more about treatment for muscle-invasive tumours.
Topics on this page:
- The bladder
- Layers of the bladder
- Types of bladder cancer
- Urothelial carcinoma of the ureter or kidney
- Who gets bladder cancer?
- What causes bladder cancer?
The bladder is a muscular sac that stores urine. It is located in the pelvis and is part of the urinary system.
As well as the bladder, the urinary system includes two kidneys, two tubes called ureters leading into the bladder, and another tube called the urethra leading out of the bladder.
In women, the urethra is a short tube that opens in front of the birth canal (vagina). In men, the tube is longer and passes through the prostate and down the penis.
The kidneys produce urine, which travels to the bladder through the ureters. The bladder is like a balloon and inflates as it fills. When it is time to go to the toilet, the bladder muscle contracts and urine is passed through the urethra and out of the body.
Layers of the bladder
There are four main layers of tissue in the bladder:
- urothelium – the innermost layer. It is lined with cells that stop urine being absorbed into the body. These cells are called urothelial cells
- lamina propria – a layer of tissue and blood vessels surrounding the urothelium
- muscularis propria – the thickest layer. It consists of muscle that contracts to empty the bladder
- perivesical tissue – the outermost layer. It is made up mostly of fatty tissue that separates the bladder from nearby organs.
Types of bladder cancer
There are three main types of bladder cancer. They are named after the cell type in which the cancer first develops.
About 80–90% of all bladder cancers start from the urothelial cells that line the bladder wall. This is sometimes called transitional cell carcinoma.
Urothelial carcinoma can be papillary or flat:
- Papillary urothelial carcinoma – has slender, finger-like projections and grows towards the hollow centre of the bladder. Most urothelial carcinomas are papillary.
Flat urothelial carcinoma – grows flat on the bladder wall without developing any finger-like projections. Carcinoma in situ is a type of flat urothelial carcinoma.
Urothelial carcinoma can also occur in the ureters and kidneys (see next section).
Squamous cell carcinoma
This type of cancer starts in the thin, flat cells in the lining of the bladder. It accounts for 1–2% of all bladder cancers and is more likely to be invasive.
This cancer develops from the mucus-producing cells of the bladder. It makes up about 1% of all cases and is likely to be invasive.
Other types of bladder cancer
Rarer types of bladder cancer include sarcomas (starting in the muscle) and aggressive forms called small cell carcinoma, plasmacytoid carcinoma and micropapillary carcinoma.
Urothelial carcinoma of the ureter or kidney
Urothelial carcinoma is the most common form of bladder cancer, but occasionally it can occur in a ureter or kidney.
Much of the information about bladder cancer will be relevant if you have been diagnosed with urothelial cancer of the kidney or ureter. Symptoms include blood in the urine and back pain.
Many of the same tests will be used for diagnosis, but instead of a cystoscopy, you will have a ureteroscopy, which uses a thin instrument with a light to examine the ureter and kidney.
The most common treatment is surgery to remove the kidney, ureter and part of the bladder (nephroureterectomy). Sometimes, only part of the ureter or kidney needs to be removed (segmental resection). Chemotherapy or immunotherapy may be used after surgery.
Who gets bladder cancer?
Each year, more than 2400 Australians are diagnosed with bladder cancer. Most people diagnosed with bladder cancer are 60 or older.
Men are three to four times more likely than women to be diagnosed with bladder cancer. Women have about a 1 in 430 chance of being diagnosed with bladder cancer before the age of 75. For men, the chance is about 1 in 110, making it one of the top 10 most common cancers in men.
What causes bladder cancer?
Research shows that people with certain risk factors are more likely to develop bladder cancer. These include:
- smoking – cigarette smokers are up to six times more likely than nonsmokers to develop bladder cancer
- older age – most people with bladder cancer are over 60, and the risk increases with age
- being male – men are three times more likely than women to develop bladder cancer
- chemical exposure at work – chemicals called aromatic amines, benzene products and aniline dyes have been linked to bladder cancer; these chemicals are used in rubber and plastics manufacturing and in the dye industry and sometimes in the work of painters, machinists, printers, hairdressers and truck drivers
- chronic infections – squamous cell carcinoma has been associated with urinary tract infections (including parasite infections, although these are very rare in Australia) and untreated bladder stones
- long-term catheter use – long-term urinary catheter use may be linked with squamous cell carcinoma
- previous cancer treatments – treatments that have been linked to bladder cancer include the chemotherapy drug cyclophosphamide and radiotherapy to the pelvic area (sometimes given for prostate cancer and gynaecological cancers)
- diabetes treatment – diabetes medicines containing pioglitazone can increase the risk of bladder cancer
- personal or family history – a small number of bladder cancers are associated with an inherited gene.