What is Stomach Cancer? Gastric Cancer Risks and Causes

Stomach cancer or gastric cancer is a malignant tumor that develops in the stomach. Although there may be benign growths like certain types of stomach polyps, most of the tumors that develop in the stomach are malignant tumors. Generally the term gastric cancer refers to an adenocarcinoma of stomach as it is the most common form of malignant tumor of the stomach.

Risk Factors for Stomach Cancer

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Stomach cancer affects men more than women and is more often seen in the over 50 age group. Overall, stomach cancer is considered to be an outcome of multiple factors. Several risk factors have been identified from epidemiological studies and can be grouped as acquired factors, genetic factors and precancerous conditions.

Acquired

  • Diet/nutritional factors
    • high salt consumption (salted or pickled foods)
    • excessive smoked foods (like smoked fish)
    • high nitrates/nitrites consumption
    • high carbohydrates intake
    • lack of fresh fruit and vegetables in diet
    • low dietary vitamin A and C
  • Infections
    • Helicobacter pylori (H.pylori)
    • Epstein-Barr virus (EBV)
  • Cigarette smoking
  • Poor quality drinking water
  • Occupational risk factors
    • Coal
    • Rubber
  • Exposure to radiation
  • Prior gastric surgery for benign gastric ulcer disease

Genetic

  • Family history of stomach cancer
  • Pernicious anemia
  • Hereditary nonpolyposis colorectal cancer

Precancerous

  • Chronic atrophic gastritis
  • Adenomatous gastric polyps of 2 cm or more
  • Pernicious anemia
  • Intestinal metaplasia
  • Gastric dysplasia
  • Hypertrophic gastropathy (Menetrier’s disease)
  • Chronic gastric ulcer (stomach ulcers)
  • Stump of previous gastric removal surgery

Other risk factors are more significant for cancer at the gastroesophageal junction or cardiac end of stomach and includes :

  • high calorie intake
  • increased body mass index (obesity)
  • chronic gastroesophageal reflux disease (GERD)

Causes of Stomach Cancer

The exact cause of stomach cancer is unknown but this type of malignancy is more likely to arise in a person with one or more of the risk factors.

One of the more widely accepted explanations of stomach cancer revolves around chronic H.pylori infection. Persistent inflammation, which is often seen with chronic H.pylori infection leads to atrophic gastritis. This reduces the acidity of the stomach juices (achlorhydria) and allows for other bacterial strains to thrive in this environment. Some of these bacteria are capable of converting dietary nitrates to nitrites and can lead to the formation of toxic N-nitroso compounds.

These compounds in combination with other risk factors, like genetic factors, cigarette smoking and so on, produce genetic mutations and abnormal proliferation of the stomach cells. This can lead to metaplasia and dysplasia of the gastric epithelial cells lining the stomach which eventually results in cancer. Other risk factors, even in the absence of H.pylori infection, may also lead to genetic mutations of the stomach cells which can ultimately contribute to cancer development.

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