Gastric Cancer Prevention Luis S. Mon, M.D., F.A.C.S. Carlos A. Perurena, M.D. Gastric Cancer Prevention • Drs. Mon and Perurena are proffesors or Surgery at the University of Panama´s Medical School. They can be contacted at email@example.com • Gastric Cancer is the fifth most frequent cancer and the second most lethal in the Republic of Panama. Gastric Cancer Prevention Learning Objectives: 1. State the basic biological characteristics of Adenocarcinoma of the Stomach. 2. Describe the principal epidemiological features of the disease. 3. Recognize the most probable risk factors for the disease. Performance Objectives: 1. Propose specific strategies for Gastric Cancer primary prevention. 2. Propose strategies for Gastric Cancer secondary prevention. Gastric Cancer Prevention •Biology •Epidemiology •Risk Factors •Primary Prevention •Secondary Prevention Gastric Cancer Prevention: Biology • There are several Hystological types of Gastric Cancer of which adenocarcinoma is by far the most frequent. • Sarcomas and Lymphomas can also occur. • This presentation refers basically to adenocarcinoma. Gastric Cancer Prevention Biology: Hystopathology Two types of adenocarcinoma are recognized: 1. Intestinal: resembles colon cancer, can be polypoid or ulcerated, occurs usually in the distal stomach and has a prolonged pre-cancerous phase. Gastric Cancer Prevention Biology: Hystopathology 2. Difusse: Extends widely with no distinct margins and the glandular structure is rarely present. Patients tend to be younger and have a worst prognosis. Gastric Cancer Prevention Biology: Hystopathology • Adenocarcinoma is considered early when it´s confined to the mucosa and sub-mucosa, irrespective of lymph node affection. • Otherwise it’s called advanced. Gastric Cancer Prevention: Epidemiology • Infrequent before 40 years of age. • Twice as frequent in men than in women. • Leading cause of death from cancer worldwide. Gastric Cancer Prevention: Epidemiology • Highest incidence in Japan, South America and Eastern Europe. • Adjusted rate worldwide is 15.62 per 100 000 • Adjusted rate for Latin America is variable. Gastric Cancer Prevention: Epidemiology • In Costa Rica the incidence rate for men is 51.5 and 28.7 for women. • In Panama ( a country that borders Costa Rica) the global rate is 11.5 Gastric Cancer Prevention: Epidemiology • In the United States the incidence has been decreasing and unexplainedly the cancer has migrated proximally. Gastro-esophageal lesions are more frequent than antral lesions. Gastric Cancer: Risk Factors and Primary Prevention • Gastric Cancer is a very common disease that carries a high mortality. • The diagnosis in early phases, when better results should be expected, is difficult due to the unspecifity of early symptoms. Gastric Cancer: Risk Factors and Primary Prevention • Recognition of risk factors and application of strategies directed towards their elimination are of paramount importance. • We will discuss the most probable and convincing risk factors related to this disease. Gastric Cancer Prevention: Chronic Atrophic Gastritis • Chronic Atrophic Gastritis is thought to be the initial step in the development of most Gastric Cancers. Gastric Cancer Prevention: Chronic Atrophic Gastritis Chronic Atrophic Gastritis has been shown to appear in patients with: 1. Tobacco use. 2. H. pylori infection. (cont.) Gastric Cancer Prevention: Chronic Atrophic Gastritis 3. Diets with high levels of nitrites, nitrates, salt and smoked foods. 4. Previous Gastric Surgery. 5. Pernicious Anemia. Gastric Cancer Prevention: Tobacco • Smoking increases the risk of Gastric Cancer by 50% to 60% • It is estimated that smoking tobacco is responsible for 11% of all Stomach Cancers worldwide. Gastric Cancer Prevention: Tobacco • Tobacco use decreases the levels of Carotenoids and Vitamin C which act as protective agents against this disease. Gastric Cancer Prevention: Tobacco • Tobacco use is associated with Helycobacter pylori infection which in turn leads to Atrophic Gastritis. Gastric Cancer Prevention: Tobacco • Smoking cessation returns the risk to that of the general population after 20 years. Gastric Cancer Prevention: Helycobacter pylori • H. pylori is associated with a two to sixfold increase in the risk of developing Gastric Cancer. • Many believe that genetic and environmental factors also need to be present for H. pylori to cause cancer. Gastric Cancer Prevention: Helycobacter pylori • In 1994 the World Health Organization designated H. pylori a Group 1 carcinogen Gastric Cancer Prevention: Dietary Factors • Consumption of fruit, vegetables and fiber has shown, in the majority of controled studies published, a protective effect against Gastric Cancer. • This effect is probably due to Vitamin C or carotenes. Gastric Cancer Prevention: Dietary Factors • Nitrates and nitrites found in salted, smoked and dried foods lead to atrophic Gastritis which in turn leads to Gastric Cancer. Gastric Cancer Prevention: Genetic Factors All of the following genetic factors have been shown to increase the risk of Gastric Cancer. Gastric Cancer Prevention: Genetic Factors • Blood type A. • Hereditary non-polyposis colorectal cancer. • e-cadherin gene mutations. • A first degree relative with Gastric Cancer. Gastric Cancer Prevention: Genetic Factors • Presently they are not subject to preventive measures except for prophylactic gastrectomy in e-cadherin mutations. Gastric Cancer Prevention: Secondry Prevention • Secondary prevention is the “early” detection of cancer through screening. • This is done in populations where the disease is a major health problem. • Examples of this approach can be found in Japan and Costa Rica. Gastric Cancer Prevention: Secondary Prevention • In Japan gas-contrast Stomach Fluorography is done in the mass population. (cont.) Gastric Cancer Prevention: Secondary Prevention • Those considered abnormal (about 13%) will undergo further studies, including endoscopy and biopsy. Gastric Cancer Prevention: Conclusions The best primary prevention strategies are: Gastric Cancer Prevention: Conclusions • Smoking avoidance or cessation. • Diets rich in fruit, vegetables and fiber. • Avoidance of salted, smoked and poorly preserved foods. • Erradication of H. pylori. Gastric Cancer Prevention: Conclusions • Mass screening is a viable strategy in high risk populations.
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