November is Stomach/Gastric Cancer Awareness month. The stomach is responsible for receiving and digesting bolus (chewed foods)–essentially preparing the foods for nutrient absorption in the small intestines. Cancer arises when cells in the stomach lining accumulate a buildup of mutations, leading to loss of cell cycle regulations. Risk factors of gastric cancer include age 55 years and older, male, smoking, genetics, and diet choices. It is also highly correlated with previous bacterial infection from Helicobacter pylori, which will be discussed in this article.


What is H. pylori?

H. pylori is a spiral rod shaped bacterium that thrive in microaerophillic conditions (requiring low oxygen concentration, much like your stomach environment). It is also equipped with tail-like “flagella” used for navigation in the stomach. It is thought that the bugs propel themselves quickly away from the acidic conditions of the stomach contents towards the stomach mucosal lining, which is less acidic. Once H. pylori establish themselves in the mucosal lining, they cause inflammation and damage, and eventually acid will breach to deeper stomach lining layers, causing ulcers and gastric pains.  


H. pylori-associated peptic ulcers

Traditionally, stomach ulcers and inflammation were associated with stress, spicy foods, and smoking. However, physician pathologist team Dr. Barry Marshall and Dr. Robin Warren frequently observed helical shaped bacteria in the stomach slides of patients suffering from gastric ulcers, and were convinced that the bacteria played a part in causing the stomach ulcers. In the summer of 1984, Dr. Marshall became a guinea pig doctor and infected himself by ingesting broth filled with the bacteria. Subsequently, he cured himself with antibiotics–thus establishing the link between stomach ulcers and H. pylori. Their discovery led them to the ultimate accolade: the 2005 Nobel Prize in Medicine.

H. pylori, or the Corkscrew Bugis found in the environment, but is closely associated with where hygiene is poor. Therefore, a person may be infected via contaminated water, food, and more. Direct transmission from an infected person to another is also very likely. In developing countries, infection mostly occurs during childhood and affects more than 80% of the population. In industrialized areas, the percentage is below 40%.

People colonized with H. pylori have a 10-20% chance of developing stomach ulcers, and a 1-2% risk of developing gastric cancer. The factors involved include bacterial-host interaction and environmental factors.



Sufferers from stomach ulcers likely have dull aching stomach pains, especially in between meals when the stomach is empty and acid can directly irritate the ulcers. Symptoms may be alleviated by eating, especially non-acidic foods. Other signs include bloating or nausea. If ulcer bleeding occurs, one may vomit blood or coffee-ground like substance or have bloody stools, sharp pains in the stomach, fatigue, and more.

Overtime if left untreated, H. pylori infection may lead to gastric cancer. Symptoms include general gastric distress (heartburn, stomach pains, bloating, small appetite, vomiting).    



Because of the widespread nature of H. pylori and that it does not always cause disease, doctors will only screen for and treat H. pylori colonization if symptoms are present. Treatment usually include multiple antibiotic classes combined with stomach acid reducers or bismuth subsalicylate. It is important to adhere to the full course of treatment as failure to do so will harbor antibiotic resistance in H. pylori, making future treatments more difficult. Avoid NSAIDs pain killers, spicy foods, smoking, and alcohol, as these will usually worsen your symptoms.  

Prevention is also effective in reducing H. pylori transmission, such as being mindful about handwashing and avoiding contaminated sources.



Kusters JG, van Vliet AH, Kuipers EJ. Pathogenesis of Helicobacter pylori infection. Clin Microbiol Rev. 2006 Jul;19(3):449-90.

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