aetiology

Last edited 11/2020 and last reviewed 11/2020

There are a number of factors which are known to increase the risk of developing stomach cancer.

The presence of the bacterium Heliobactor pylori (H.pylori) has been identified as the most important risk for developing stomach cancer (1)

• the chronic inflammation in the stomach due to the presence of H.pylori induces cell changes in the stomach mucosa; a precursor to the development of the condition. Diagnosis and treatment of people with H.pylori since the 1990’s is thought to beinstrumental in an overall decline in the incidence of stomach cancer seen in many countries including the UK (1)
• other important population characteristics that increase the risk of gastric adenocarcinoma are age, sex, social deprivation and ethnic origin. Incidence rates rise steadily from around age 45-49 years with the highest rates in the 85 to 89 age group (2)
  • males have a higher incidence of gastric adenocarcinoma than females accounting for 65% of all new cases in the UK(2). Incidence rates in males are 86% higher and in females 93% higher in the most deprived areas compared with the least deprived (2)

A report by the National Cancer Intelligence Network in 2009 reported that people of Caucasian ethnicity were more likely to develop stomach cancer compared to people of Asian origin but less likely to develop the condition than those of a Black African or Caribbean origin (3)

• the International Agency for Research on Cancer (IARC) have listed the particular environmental factors where there is convincing evidence that exposure increases the risk of developing gastric adenocarcinoma (4)
• these include tobacco smoking, obesity, occupations involving rubber production and exposure to X-radiation or gamma radiation
• environmental factors with limited or probable evidence of increasing the risk of gastric adenocarcinoma include; asbestos; Epstein-Barr virus (a common virus in humans also known as glandular fever); inorganic lead compounds; nitrate or nitrite; traditional Asian pickled vegetables; processed meat; alcohol; and foods preserved by salting

Other possible risk factors include:

• genetic - a relatively weak influence:
• more common in individuals of blood group A
• positive family history in 4% of cases
• increased incidence in certain ethnic and racial groups - blacks, American Indians, Maori's, Japanese
  
  
• host factors - diseases that produce hypochlorhydric or achlorhydric states associated with an increased risk; encourage bacterial colonisation and conversion of dietary nitrates and nitrites into nitrosamines:
• pernicious anaemia
• chronic gastritis - Menetrier's disease; Helicobacter pylori
• partial gastrectomy - risk of malignancy in residual stump is increased 2-6 fold
  
  
• gastric neoplastic polyps - especially those arising on a background of chronic gastritis
  
  
• gastric ulcers, especially greater curve ulcers more than 2 cm in size

Reference:

• Mukaisho K, Nakayama T, Hagiwara T, Hattori T and Sugihara H. Two distinct etiologies of gastric cardia adenocarcinoma: interactions among pH, Helicobacter pylori, and bile acids. Front. Microbiol. 2015: 6:412.
• Cancer Research UK,  https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/stomach-cancer/incidence Accessed November 2020.
• National Cancer Intelligence Network. Cancer incidence and survival by major ethnic group, England, 2002 – 2006. 2009; London UK.
• IARC.  Monographs on the Identification of Carcinogenic Hazards to Humans; Agents Classified by the IARC Monographs, Volumes 1–127 https://monographs.iarc.fr/agents-classified-by-the-iarc/ June 2020. Accessed August 2020.