Stomach cancer is cancer that starts anywhere inside the stomach or the stomach wall. It’s also called gastric cancer.
Who gets it
Stomach cancer is more common in men than women. More than 5 out of 10 cases (50%) occur in people aged 75 or over.
Many stomach cancers are linked to lifestyle or environmental factors, including diet. Stomach cancer is linked with a bacteria that lives in the stomach called Helicobacter pylori. But not everyone with Helicobacter pylori will develop stomach cancer.
The stomach is part of the digestive system. It lies just under the lungs. The top of the stomach is joined to the bottom of the oesophagus (food pipe) and the other end is attached to the bowel.
The stomach is a muscular bag that has three main parts. They are the:
- top or the fundus
- middle or the body of the stomach
- bottom or the antrum or pylorus
At each end of the stomach there is a valve called a sphincter. They control the movement of food through the digestive system. They are the:
- cardiac sphincter - sitting at the top and joining the oesophagus to the stomach
- pyloric sphincter which is at the bottom and joins the stomach to the bowel
How the stomach works
Food passes from the oesophagus into the stomach. It then holds the food and breaks it down (digests) so our body can absorb it. It does this by producing juices and mixing the food up with them so it is easily digestible.
Glands in the wall of the stomach make the juices. These juices are stomach acid and a protein called pepsin. They begin to flow as soon as we smell something.
The muscle wall of the stomach contracts, churning the food with the juices and changing it to a thick liquid. It takes a couple of hours for this to happen. After that it moves into the bowel where the body absorbs it.
Even when it's empty, the stomach continues to produce juices and hormones. So, to protect the lining of the stomach from the acid and pepsin it also produces a thick mucus.
Where it starts
Cancer can start in any part of the stomach or the stomach wall. Your treatment can depend on where the cancer starts.
Most stomach cancers start in the gland cells in the inner stomach lining. These are called adenocarcinomas.
Some cancers can also start in immune system cells. This is called non Hodgkins lymphoma.
Cancer can also start in the hormone cells in the stomach. These are called neuroendocrine cancers.
The treatment you need if you have one of these types of cancer is different to adenocarcinomas.
How common it is
Around 7,000 people are diagnosed with stomach cancer in the UK each year. That’s about 19 cases diagnosed every day. The number of people in the UK diagnosed with stomach cancer has been falling for the last 10 years.
In adults, it’s the 13th most common cancer in men and the 15th most common cancer in women.