Introduction: Gastric cancer is the second most leading cause of cancer associated deaths, worldwide. Japan, China, former USSR and certain countries in Latin America have reported highest incidence of stomach cancer. The high mortality rate of gastric cancer was reported in Eastern Asia and the lowest rate of gastric cancer was reported in North America. Nevertheless, it causes a worrisome level of mortality in the U.S. In 2010, gastric cancer or stomach cancer was responsible for 10,570 deaths in the United States, as estimated by National Cancer Institute. (National Cancer Institute, 2016)
A majority (85%) of the gastric cancers are adenocarcinomas affecting the gastric mucosa. The cancer can occur either in the upper (pylorus) part of the stomach or in the middle part of the stomach or in the lower (cardia) part of the stomach. (Gore, 2010)
Risk factors: Environmental and genetic factors can modify risk for gastric cancer or stomach cancer. Family history of gastric cancer can increase risk for genetic predisposition to cancer. Cancer of genetic origin usually have an early age of onset and affect more than one organ. It is normal for physicians to suspect stomach cancer in patients having a history of cancer in their family. People with blood group A, also have a higher risk for gastric cancer, when compared to other blood groups. (National Cancer Institute, 2016)
Helicobacter pylori is a common gastric pathogen and can cause stomach cancer. By promoting chronic inflammation, the bacteria injures the gastric mucosa, leading to a non-healing ulcer, which eventually progresses to cancer. Helicobacter pylori can evade the immune system of the host to persist in the gastric and duodenal mucosa as a permanent parasite. Among all risk factors studied so far, the gram negative bacteria, was identified as the most potent risk factor. The bacteria increases risk for cancer by three fold in the infected person, when compared to an uninfected person. A pervious injury to the gastric mucosa, can increase risk of gastric cancer. People with gastric ulcer have an increased risk of developing gastric ulcer. H.pylori infection causes chronic atopic gastritis. It is the most common precursor to gastric cancer. In the intestinal subtype of gastric cancer, type III intestinal metaplasia is a common cause of gastric cancer. Treatment for H. pylori infection, helps reduce atopic gastritis and intestinal metaplasia. (Gore, 2010)
Individuals with a history of adenomatous gastric polyp, also has a high risk for gastric cancer. A majority of the patients with gastric polyp are asymptomatic. It arises from idiopathic etiology and adenoma is the precursor stage of adenocarcinoma. (Jung, 2013)
The incidence of cancer is higher in men, than in women. In the year 2010, stomach cancer cases were 13,000 in men and 8000 in women (National Cancer Institute, 2016). Men have two times higher risk for this cancer than women. A positive association between smoking and gastric cancer in men was identified (Doll, Peto, Boreham & Sutherland, 2005). The other factors that predispose men to this disease is not known. (Gore, 2010)
Pernicious anemia is also a risk factor for stomach cancer. A blood test can help identify anemia. Anemia can also occur as a consequence of cancer. The pathogenesis as to how anemia develops into cancer is unknown. (Gore, 2010)
Dietary habits can modify a person’s risk for stomach cancer. While salty food like smoked and preserved meat increases risk for stomach cancer; fruits and vegetable lowers risk for stomach cancer. Eating red meat, twice daily also increases risk for stomach cancer. Barbequed meat or well done meat are particularly dangerous in this aspect. (Gore, 2010; Zhu et al., 2013)
The risk for stomach cancer increases with age. The majority of the incidence is seen in individuals who are above 50 years of age. In about 10% of the case, the cancer develops in more than one location. When compared to the cancer occurring in the elderly, the presentation of cancer in younger subjects are more aggressive and have poor prognosis. Gastric cancer can also develop gradually over the year in individuals who underwent distal gastrectomy or gasteroenterostomy. (Gore, 2010)
Prevention by modifying risk: Lifestyle is an important disease modifying factor. Reducing stress and adopting an organic lifestyle can significantly reduce risk for stomach cancer. Similarly, treating precancerous stages like H. pylori infections, ulcers and polyps with medicines, can lower risk for this cancer. Aspirin and vitamin C intake were associated with a decrease in the incidence of gastric cancer.
Screening test for stomach cancer: Presently there is no unique screening test for stomach cancer. Upper endoscopy, helps to identify gastric cancer in most cases. Ultrasound, MRI or CT scans are also used to diagnose and stage stomach cancer. Blood tests can be done to identify anemia. Esophagogastroduodenoscopy, along with biopsy, is used to confirm the diseases. Stool test will help identify blood in the stools. (Gore, 2010)
Conclusion: Most cases of gastric cancer are diagnosed only in later stages. The overall 5 year survival rate of stomach cancer is 28%. The survival rate is higher when the cancer affects the lower part of the stomach and lower when it affects the upper part. Weight loss, persistent abdominal pain, dysphagia are commonly observed symptoms of stomach cancer. The patient may feel full or blotted, after a small meal itself. Nausea, vomiting, melena and hematemesis are also reported. Stomach cancer affects the inner layer of the stomach and gradually invades deeper parts. The original cancer can also break and spread through blood and lymph to the nearby or distance organ. It is common to observe cancer metastasis in the lymph nodes that are near the cancer site. (Gore, 2010)
References
Cancer Genetics Risk Assessment and Counseling. (2016). National Cancer Institute. Retrieved 22 March 2016, from http://www.cancer.gov/about-cancer/causes-prevention/genetics/risk-assessment-pdq
Gore, R. (2010). Gastric cancer. Cambridge, UK: Cambridge University Press.
Doll, R., Peto, R., Boreham, J., & Sutherland, I. (2005). Mortality from cancer in relation to smoking: 50 years observations on British doctors. Br J Cancer. http://dx.doi.org/10.1038 /sj.bjc.6602359
Jung, J. (2013). Gastric Polyps and Protruding Type Gastric Cancer. Clinical Endoscopy, 46(3), 243. http://dx.doi.org/10.5946/ce.2013.46.3.243
Zhu, H., Yang, X., Zhang, C., Zhu, C., Tao, G., & Zhao, L. et al. (2013). Red and Processed Meat Intake Is Associated with Higher Gastric Cancer Risk: A Meta-Analysis of Epidemiological Observational Studies. Plos ONE, 8(8), e70955. http://dx.doi.org/10.1371 /journal.pone.0070955
