Gastric Cancer Screening/Prevention
Information about the prevention of cancer and the science of screening appropriate individuals at high risk of developing cancer is gaining interest. Physicians and individuals alike recognize that the best “treatment” of cancer is preventing its occurrence in the first place or detecting it early when it may be most treatable.
Gastric cancer is characterized by the presence of cancer cells in the tissues of the stomach, which is located in the upper abdomen. Worldwide, gastric cancer is the third leading cause of cancer death in men and the fifth leading cause of cancer death in women.1
The chance of an individual developing cancer depends on both genetic and non-genetic factors. A genetic factor is an inherited, unchangeable trait, while a non-genetic factor is a variable in a person’s environment, which can often be changed. Non-genetic factors may include diet, exercise, or exposure to other substances present in our surroundings. These non-genetic factors are often referred to as environmental factors. Some non-genetic factors play a role in facilitating the process of healthy cells turning cancerous (e.g. the correlation between smoking and lung cancer) while other cancers have no known environmental correlation but are known to have a genetic predisposition. A genetic predisposition means that a person may be at higher risk for a certain cancer if a family member has that type of cancer.
HEREDITY OR GENETIC FACTORS
Researchers are beginning to identify genetic factors that contribute to the development of gastric cancer in some individuals. Specifically, the E-cadherin gene (CDH1) has been associated with a high risk of gastric cancer. Hereditary diffuse gastric cancer is a rare and deadly form of gastric cancer that can result from CDH1 mutations. Parents who carry this genetic mutation have a 50% chance of passing it along to their offspring. Three out of four people who inherit this genetic mutation will eventually develop gastric cancer.
ENVIRONMENTAL OR NON-GENETIC FACTORS
Several risk factors have been associated with an increased risk of developing gastric cancer. These include infection with the Helicobacter pylori (H. pylori) bacterium, smoking, high consumption of smoked or salted foods, and low intake of fruits and vegetables. In addition, poor drinking water and a lack of refrigeration appear to contribute to the development of gastric cancer.
H. Pylori: The primary risk factor associated with gastric cancer is infection with the bacterium, Helicobacter pylori (H. pylori). H. pylori infection is common, but most people who are infected do not develop gastric cancer. The bacterium may be spread from person to person as well as through contact with contaminated food or water. Infection with H. pylori causes a reduction in the normal acid production and a shrinkage and loss of cells (called atrophy) in the stomach. Atrophy of the stomach is considered to be a precancerous condition. It can take decades for the precancerous conditions caused by H. pylori infection to develop into cancer. Individuals who live in regions that have high gastric cancer rates are often plagued with H. pylori stomach infections that develop early in life.
Two-thirds of cancer deaths in the U.S. can be linked to tobacco use, poor diet, obesity and lack of exercise. All of these factors can be modified. Nevertheless, an awareness of the opportunity to prevent cancer through changes in lifestyle is still under-appreciated.
Treatment of H. pylori infection: According to studies conducted in parts of the world where gastric cancer is common, treatment of H. pylori infections may reduce the risk of gastric cancer. In a large combined analysis of people infected with H. pylori, gastric cancer developed in 1.1% of those who received treatment to eradicate the infection and 1.7% of those who did not receive treatment.2
Aspirin: Aspirin is a type of non-steroid anti-inflammatory drug (NSAID). Studies have suggested that regular use of aspirin—but not other types of NSAIDs—may reduce the risk of gastric cancer.3 Because regular aspirin use also carries some risks, however, people who are considering taking aspirin on a regular basis are advised to talk with their physician.
Diet: Diet is a fertile area for immediate individual and societal intervention to decrease the risk of developing certain cancers. Numerous studies have provided a wealth of often-contradictory information about the detrimental and protective factors of different foods.
In the case of gastric cancer, risk appears to be increased by high consumption of smoked, salted, or pickled foods, and decreased by regular consumption of fresh fruits and vegetables.4
Avoid tobacco smoke: Smoking increases the risk of many types of cancer, including gastric cancer. Never smoking (or quitting if you’ve started) provides many health benefits.
SCREENING AND EARLY DETECTION
For many types of cancer, progress in the areas of cancer screening and treatment has offered promise for earlier detection and higher cure rates. The term screening refers to the regular use of certain examinations or tests in persons who do not have any symptoms of a cancer but are at high risk for that cancer. When individuals are at high risk for a type of cancer, this means that they have certain characteristics or exposures, called risk factors that make them more likely to develop that type of cancer than those who do not have these risk factors. The risk factors are different for different types of cancer. An awareness of these risk factors is important because 1) some risk factors can be changed (such as smoking or dietary intake), thus decreasing the risk for developing the associated cancer; and 2) persons who are at high risk for developing a cancer can often undergo regular screening measures that are recommended for that cancer type. Researchers continue to study which characteristics or exposures are associated with an increased risk for various cancers, allowing for the use of more effective prevention, early detection and treatment strategies.
Gastric cancer rates have been steadily declining in the United States and at this point, routine screening for this cancer is not performed. Mass screening programs for gastric cancer have been most effective in high-risk areas, such as Japan. Early gastric cancer has a high cure rate when it is surgically removed. In some Japanese studies, as many as 40% of newly diagnosed patients have early gastric cancer and as many as 60% of patients are actively participating in mass screening programs. Routine screening in Japan involves gastroscopy.
Gastroscopy: A gastroscopy is an examination performed through an endoscope, which is a flexible tube inserted through the esophagus that allows the physician to visualize, photograph and biopsy (sample) the cancer.