There are many suspected causes of stomach cancer. Like many types of cancer, there are both internal factors, such as genetic predisposition, and external factors, such as exposure to environmental toxins. Like cervical cancer, however, a particular pathogen — in this case, certain toxins — has also been identified as one of the most common causes of stomach cancer.
Among the internal factors that can lead to stomach cancer are uncommon genetic diseases such as intestinal metaplasia, in which the regenerative lining of the stomach develops or changes into the wrong type of intestinal tissue. Autoimmune atrophic gastritis is a likewise rare condition in which the body’s immune system mistakenly believes that the lining of the stomach is foreign tissue and proceeds to try and destroy it. Simple gastritis, the inflammation and irritation of the stomach lining, is also a risk factor if the condition is chronic.
There are other internal factors among the causes of stomach cancer. Its incidence is three times more likely to affect males. The female hormone estrogen is believed to provide some protective function against stomach cancer. Certain ethnic groups, such as Japanese, have a higher per capita incidence of this form of cancer, but it is undetermined whether the reason is genetic or lifestyle.
It stands to reason that the most likely causes of stomach cancer, also called gastric cancer, are toxins ingested orally. Two very common toxins, particularly when combined, are proven risk factors: excessive tobacco and alcohol consumption. It is estimated that heavy smokers are twice as likely as non-smokers to be stricken by stomach cancer, usually near its connection with the esophagus pipe. Alcohol strips the protective mucus coating the stomach, making its lining tissue vulnerable to carcinogenic agents.
Whether or not other oral consumptions or diets in general are risk factors for stomach cancer is still debated. Some health organizations have issued warnings against smoked, salt-cured, and pickled foods. Many of the same organizations correspondingly suggest that antioxidants such as vitamins A and C in fresh fruits and vegetables are stomach cancer preventatives.
A bacterial infection is one of the principal, pinpointed causes of stomach cancer. The culprit is Helicobater pylori. An estimated 50% of the world’s population harbors this bacteria in their upper digestive tract. Up to 80% of these people experience little to no adverse effect from the bug’s presence; others may experience mild to serious reactions, including gastritis. Around 2% of infected people will develop stomach cancer.
An estimated ten percent of stomach cancers have been diagnosed to have had a genetic cause. In contrast, in 65-80% of cases, the bacterium Helicobacter pylori has been implicated. One of the pressing difficulties with this deadly cancer is that it is often asymptomatic, and by the time any physical symptoms are noticed, it may already have advanced to a late stage. Furthermore, stomach cancer spreads easily to other organs, such as the lungs, liver, and lymph nodes.