Bladder cancer begins when cells in the inner lining of the bladder become abnormal. This causes them to grow and divide out of control. As the cancer grows, it may start to spread into the bladder wall. Some of these cancer cells can also break off and travel to other parts of the body.

Learn more about: 

• What is bladder cancer?
• Types of bladder cancer
• The bladder
• Who gets bladder cancer?
• What causes bladder cancer?

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What is bladder cancer?

The treatment for bladder cancer depends on how invasive it is – that is, how far the cancer has grown into the layers of the bladder, and whether there are any signs of cancer outside the bladder.

Non-muscle-invasive bladder cancer (NMIBC) – The cancer cells are found only in the inner lining of the bladder (urothelium) or the next layer of tissue (lamina propria) and haven’t grown into the deeper layers of the bladder wall. These cancers can be classed as low, medium or high risk depending on how they look when examined under a microscope. Learn more about treatment for non-muscle-invasive tumours.

Muscle-invasive bladder cancer (MIBC) – The cancer has spread beyond the urothelium and lamina propria into the layer of muscle (muscularis propria), or sometimes through the bladder wall into the surrounding fatty tissue. These cancers can sometimes spread to lymph nodes close to the bladder. Learn more about treatment for muscle-invasive tumours.

Advanced bladder cancer – The cancer has spread (metastasised) outside of the bladder into other organs of the body. Learn more about treatment for advanced bladder cancer. 

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Types of bladder cancer

There are three main types of bladder cancer. They are named after the type of cell the cancer starts in.

urothelial carcinoma	Most bladder cancers (80–90%) are urothelial carcinomas. This type starts in the urothelial cells lining the bladder wall and is also known as transitional cell carcinoma (TCC). Urothelial carcinoma can sometimes occur in the ureters and kidneys.
squamous cell carcinoma	This type starts in 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.
adenocarcinoma	This cancer develops from the glandular cells in the bladder. It makes up about 1% of all bladder cancers and is likely to be invasive.

There are also rarer types of bladder cancer. These include sarcomas, which start in the muscle, and aggressive forms called small cell carcinoma, plasmacytoid carcinoma and micropapillary carcinoma.

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The bladder

The bladder is a hollow, muscular sac that stores urine (wee or pee). 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 males, the urethra is a long tube that passes through the prostate and down the penis. In females, the urethra is shorter and opens in front of the vagina (birth canal).

The kidneys produce urine, which travels to the bladder through the ureters. The bladder is like a balloon and expands as it fills with urine. When you are ready to empty your bladder, the bladder muscle contracts and urine is passed through the urethra and out of the body.

Layers of the bladder wall

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. Mostly made up of fatty tissue, it separates the bladder from nearby organs.

The urinary system

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Who gets bladder cancer?

Each year, almost 2800 Australians are diagnosed with bladder cancer. Most people diagnosed with bladder cancer are 60 or older.

Men are three times more likely than women to be diagnosed with bladder cancer. About 1 in every 108 men will be 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 394. However, women are often diagnosed with bladder cancer at a more advanced stage.

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What causes bladder cancer?

Research shows that people with certain risk factors are more likely to develop bladder cancer. These factors include:

• smoking – cigarette smokers are up to three times more likely than nonsmokers to develop bladder cancer
• older age – most people with bladder cancer are over 60
• 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, in the dye industry, and sometimes in the work of painters, machinists, printers, hairdressers, firefighters and truck drivers
• chronic infections – squamous cell carcinoma has been linked to urinary tract infections (including parasite infections, although these are very rare in Australia) and untreated bladder stones
• long-term catheter use – using urinary catheters over a long period 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 and gynaecological cancers)
• diabetes treatment – the diabetes drug pioglitazone can increase the risk of bladder cancer
• personal or family history – an inherited gene may contribute to a small number of bladder cancers.

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