What is bladder cancer?
Bladder cancer begins when cells in the inner lining of the bladder become abnormal, which causes them to grow and divide out of control. The treatment for bladder cancer depends on how quickly the tumour cells are growing and how far the cancer has spread into the layers of the bladder.
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, sometimes called superficial bladder cancer.
The cancer has spread beyond the urothelium and lamina propria into the layer of muscle, or sometimes through the bladder wall into the surrounding fatty tissue. See treatment information for muscle invasive bladder cancer.
The bladder is a hollow 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 from the kidneys 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 urethra 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.
What types are there?
There are three main types of bladder cancer. They are named after the cell type in which the cancer first develops.
Most types of all bladder cancers (80–90%) start in the urothelial cells lining the bladder wall. This is sometimes called transitional cell carcinoma. Urothelial carcinoma can be papillary or flat (below), and can sometimes occur in the ureters and kidneys.
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 glandular cells of the bladder. It makes up about 1% of all cases and is likely to be invasive.
Rarer types of bladder cancer include sarcomas (starting in the muscle) and aggressive forms called small cell carcinoma, plasmacytoid carcinoma and micropapillary carcinoma.
How urothelial carcinoma grows
Urothelial carcinoma is divided into two subgroups depending on how it grows. Most urothelial carcinomas are papillary.
- Papillary urothelial carcinoma grows in slender, finger-like projections towards the centre of the bladder.
- Flat urothelial carcinoma, such as carcinoma in situ, grows flat on the wall of the bladder.
How common is bladder cancer?
Each year, more than 2500 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. Men have about a 1 in 114 chance of being diagnosed with bladder cancer before the age of 75, making it one of the top 10 most common cancers in men. For women, the chance is about 1 in 422. 4
What are the symptoms?
Sometimes bladder cancer doesn't have many symptoms and is found when a urine test is done for another reason. However, often people with bladder cancer do experience symptoms. These can include:
Blood in the urine (haematuria)
This is the most common symptom of bladder cancer. It often occurs suddenly, but is usually not painful. There may be only a small amount of blood in the urine and it may look red or brown. For some people, the blood may come and go, or it may appear only once or twice.
Changes in bladder habits
A burning feeling when passing urine, needing to pass urine more often or urgently, not being able to urinate when you feel the urge, and pain while urinating can also be symptoms.
Less commonly, people have pain in one side of their lower abdomen or back.
If you have any of these symptoms or are concerned, see your doctor as soon as possible.
Not everyone with these symptoms has bladder cancer. These changes might also indicate a bladder irritation or an infection. Blood in your urine can also be caused by kidney or bladder stones, and non-cancerous enlargement of the prostate in men.
Never ignore blood in your urine. Even if you've noticed blood in your urine only once and it is painless, see your doctor.
What are the risk factors?
Research shows that people with certain risk factors are more likely to develop bladder cancer. These include:
- smoking – cigarette smokers are up to three times more likely than nonsmokers to develop bladder cancer 5
- older age – most people with bladder cancer are over 60, and the risk increases with age
- being male – men are three to four 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 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 (used for various cancers) and radiation therapy to the pelvic area (sometimes given for prostate cancer and gynaecological cancers)
- diabetes treatment – the diabetes drug pioglitazone can increase the risk of bladder cancer
- personal or family history – a small number of bladder cancers are associated with an inherited gene.
Expert content reviewers:
Phil Dundee, Urological Surgeon, Epworth Hospital, VIC; David Connah, Consumer; Dr Elizabeth Hovey, Senior Staff Specialist, Nelune Comprehensive Cancer Centre, Prince of Wales Hospital, and Conjoint Senior Lecturer, University of New South Wales, NSW; Colleen McDonald, Clinical Nurse Consultant Urology, Westmead Hospital, NSW; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council Western Australia, WA; Kerry Santoro, Urology Nurse Consultant, Repatriation General Hospital, SA.
4. Australian Institute of Health and Welfare (AIHW), Australian Cancer Incidence and Mortality (ACIM) books: bladder cancer, AIHW, Canberra, 2017
5. AH Al-Zalabani et al., “Modifiable risk factors for the prevention of bladder cancer: a systematic review of meta-analyses”, European Journal of Epidemiology, vol. 31, no. 9, 2016, pp. 811–51.