Is There a Correlation Between H. Pylori and Gastric Cancer?
Li Liu, MD
Last Modified: November 1, 2001
Dear OncoLink "Ask the Experts,"
My mother was diagnosed with positive H. pylori. I understand that there is a correlation with gastric cancer. Are there initial screening methods to detect the early stage of gastric cancer and how significant is this correlation?
Li Liu, MD, OncoLink Editorial Assistant, responds:
Thank you for your interest and question.
Since the discovery of Helicobacter pylori (H. pylori) in the 1980s, much has been learned about this gram-negative spiral bacterium and its associated disease states. H. pylori can cause chronic gastritis and atrophic gastritis, which are early steps in the cancer formation (carcinogenesis) sequence (Gastroenterology 1972 Oct;63(4):584-92). Several studies have reported a significant association between H. pylori infection and gastric cancer (Gastroenterology 1993 Oct;105(4):1098-103). A multinational EUROGAST study of 17 populations from 13 different countries found a sixfold increased risk of gastric cancer in H. pylori-infected populations compared with uninfected populations (Lancet 1993 May 29;341(8857):1359-62). A recent study showed that certain strains of H. pylori produce a protein, cytotoxin-associated gene A (CagA), are more virulent in nature and produce significant amounts of gastritis and epithelial injury. Patients with CagA-positive H pylori infection have a slightly higher risk of developing stomach cancer than those with CagA-negative strains (Cancer Res 1995 May 15;55(10):2111-5).
Despite the positive association between H. pylori infection and gastric cancer, the question remains whether treatment of H. pylori infection reduces the risk of gastric cancer. One prospective study found the usefulness of H. pylori eradication in reverting precancerous lesions to be questionable (Gastroenterology 1997 Jul;113(1):25-30). The follow-up of this study remains too short to make any definitive conclusions. At present, there is insufficient data to recommend screening asymptomatic patients for H. pylori to prevent gastric cancer. However, decisions to screen based on risk factors, such as race, diet, and family history, can be made on an individual basis.
In addition to gastric carcinoma, H. pylori infection is also strongly associated with gastric lymphoma. But, the vast majority of people who carry this bacterium in their stomachs never develop cancer.
In the United States, there are three procedures commonly used when people are at risk for gastric cancer or when signs and symptoms of this disease are present; upper endoscopy, barium upper gastrointestinal radiographs, and endoscopic ultrasound. You should discuss your concern with her doctors. It is important to evaluate other risk factors, such as dietary habit, tobacco and alcohol use, previous stomach surgery, pernicious anemia, and family history of cancer.