Bladder cancer begins when cells in the bladder start to grow uncontrollably. As more cancer cells develop, they can form a tumour which can spread to other areas of the body.
How common is bladder cancer
Around 440 people are diagnosed with bladder cancer each year in Ireland. It is the 9th most common cancer in the country (not counting non melanoma skin cancer). It is the 8th most common cancer in men.
Who gets it
Bladder cancer usually takes a long time to develop, so it is most common in older people. 3 in 4 people (over 75%) who get bladder cancer in Ireland are 65 years or older. It is rarer in people under 50 but everyone needs to remain vigilent.
More men than women get bladder cancer. This may be because more men than women have smoked or been exposed to chemicals at work in recent decades.
Your bladder also stores your urine (pee) before it leaves your body. It is part of the body system that filters waste products out of your blood and makes pee. The system is called the urinary system (or urinary tract). It includes the:
- urethra ( water pipe)
You have two kidneys, one on each side of your body. The kidneys filter your blood and make urine. The urine is carried to your bladder by two tubes called the ureters.
Your bladder is like a balloon which stores urine. It’s a stretchy bag made of muscle tissue. It can hold about 500mls (just under a pint) of urine.
When we empty our bladder, the urine passes down a tube called the urethra (water pipe) and out of the body. The urethra in men passes through the prostate gland and down the penis. The urethra in women is much shorter. It passes from the bladder down to an opening just in front of the vagina.
In men, the prostate gland surrounds the lower part of the bladder.
Layers of the bladder
The wall of the bladder has several layers, which are made up of different types of cells.
The first layer is on the inside of your bladder. It is a special type of lining that stretches as the bladder fills up. It stops the urine being absorbed back into your body. The lining is called transitional epithelium. Most bladder cancers start here.
The second layer is a thin layer of connective tissue called the lamina propria.
The third layer is muscle tissue called the muscularis propria.
The fourth layer is fatty connective tissue. It separates the bladder from other body organs, such as the prostate and kidneys.
Where it starts
Bladder cancer usually starts in the lining of the innermost layer of your bladder. As the cancer grows into or through the other layers in the bladder wall, it becomes more advanced and can be harder to treat.
How your specialist treats your bladder cancer depends on how far the cancer has grown into the layers of your bladder. This tells your doctor the stage of your cancer. Bladder cancer can be divided into superficial bladder cancer or muscle invasive bladder cancer.
Transitional cell bladder cancer
About 9 out of 10 bladder cancers in Ireland (90%) are the transitional cell type. This is sometimes called urothelial cancer.
Transitional cell bladder cancer develops from the cells of the bladder lining. These are called transitional cells.
When the bladder is empty, these cells are all bunched together. When the bladder is full, they are stretched out into a single layer. These cells come into contact with waste products in the urine that may cause cancer, such as chemicals from cigarette smoke.
Transitional cell bladder cancers can behave in different ways. There are early (superficial) cancers that have not invaded the deeper layers of the bladder. And there are invasive cancers that have. They are treated differently, so it is important to know which kind you have.
Other cancers that start in the bladder
Several other types of cancer can start in the bladder, but these are all much less common than urothelial (transitional cell) cancer.
Squamous cell carcinoma: Only about 1% to 2% of bladder cancers are squamous cell carcinomas. Under a microscope, the cells look much like the flat cells that are found on the surface of the skin. Nearly all squamous cell carcinomas are invasive.
Adenocarcinoma: Only about 1% of bladder cancers are adenocarcinomas. The cancer cells have a lot in common with gland-forming cells of colon cancers. Nearly all adenocarcinomas of the bladder are invasive.
Small cell carcinoma: Less than 1% of bladder cancers are small-cell carcinomas, which start in nerve-like cells called neuroendocrine cells. These cancers often grow quickly and typically need to be treated with chemotherapy like that used for small cell carcinoma of the lung.
Sarcoma: Sarcomas start in the muscle cells of the bladder, but they are rare.