Stomach cancer: Description
Stomach cancer is a major health burden worldwide being one of the most common forms of cancer responsible for about 10% of all cancer deaths, therefore, early diagnosis and immediate treatment initiation is vital and under some circumstances may be life-saving. However, the disease is uncommon among the young generation, its prevalence increases with age with a peak between 60 and 65. Furthermore, in general, males are more likely to develop stomach cancer than women. Almost 95% of gastric neoplasms are adenocarcinomas, the rest 5% include lymphomas of the stomach and leiomyosarcomas.
Stomach cancer is one of the most common forms of cancer, however, the incidence varies greatly between the different countries – whereas, in East Asia, Central and South America and Eastern Europe the prevalence is high, in Southern Asia, Australia, New Zealand, North America and North and East Africa the incidence is lower.
It is considered that the neoplasms of the stomach develop as a result of chronic inflammation, usually, the inflammation is induced by the Helicobacter pylori infection, although some genetic and environmental factors may also contribute.
- Helicobacter pylori infection and chronic gastritis, especially autoimmune gastritis, pernicious anemia, stomach polyps;
- Smoking and alcohol abuse;
- A diet with a high intake of salt and/or smoked foods, animal fats and preserved meats and low in vegetables;
- Prior stomach resection;
- Epstein-Barr virus infection;
- There are several hereditary conditions associated with an increased risk of developing stomach cancer, including hereditary nonpolyposis colorectal cancer (HNPCC) /Lynch syndrome, E-cadherin mutation (diffuse type), familial adenomatous polyposis, and Peutz–Jeghers syndrome;
Stomach cancer can be asymptomatic or cause only mild symptoms at early stages of the disease.
Symptoms of gastric cancer are nonspecific and may include:
- Nausea and vomiting, frequent or even regular, sometimes bloodstained (hematemesis);
- Appetite loss, especially for certain foods such as meat;
- Weight loss;
- Impaired digestion;
- Early satiety and fullness of the stomach;
- Anemia (low red blood cell count)
- The pain usually develops in advanced stages of the disease, although it may precede the occurrence of cancer in case of peptic ulcer and gastritis;
Disease symptoms depend on the tumor location. For example, when the tumor is located near the esophageal sphincter are known to cause dysphagia. Tumors of the antral part of the stomach may obstruct the gastric outlet and, therefore, interfere with gastric emptying causing the appetite loss and early satiety. Tumors located in the fundus and body of the stomach are usually asymptomatic or lead to chronic blood loss and anemia.
Sometimes the tumor becomes so big that it may be palpated in the epigastrium. The cancerous cells can spread to the liver resulting in hepatomegaly (enlarged liver) and the lymph nodes, especially the supraclavicular nodes (called the Virchow node), left axillary nodes, and even umbilical nodes (called Sister Mary Joseph node). Gastric cancer may also metastasize to the spleen, transverse colon, lungs, bone marrow, bladder, kidneys, etc. Ovarian involvement is referred to as Krukenberg tumors.
Hereditary diffuse gastric cancer
Hereditary diffuse gastric cancer is a rare syndrome inherited as autosomal dominant pattern associated with an increased risk of developing a specific form of stomach cancer, characterized by the presence of the diffuse cancerous tissues with no formed tumor. The abnormal cells infiltrate the stomach lining and make it rigid and thick.
- Complete blood cell count may reveal hypochromic anemia, although the findings are nonspecific;
- The positive fecal occult blood test is suggestive of the gastrointestinal bleeding;
- Elevated С-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are quite common, however, they are also nonspecific;
- Helicobacter pylori tests are used to detect the bacteria which is known to cause gastritis and peptic ulcer and eventually may lead to stomach cancer;
- Several tumor markers are related to gastric cancer including carcinoembryonic antigen (CEA), cancer antigen (CA) 19-9, CA 50, and CA 72-4, although the clinical use of these tests is limited;
- If there are any suspicions upper gastrointestinal endoscopy should be performed, during this procedure, a tissue sample may be taken (biopsy) to examine the microstructure of the lesion and determine whether it is benign or malignant. Endoscopic ultrasonography is helpful to evaluate the stomach wall involvement and assess the size of the neoplasm;
- A chest X-ray is used to detect lung metastases;
- CT scanning is recommended to detect the involvement of the other body parts and the tumor spread;
- Whole-body PET scanning may also be performed;
Complete surgical resection of the whole tumor is the only curative treatment. When a tumor is small it may be resected endoscopically. Sometimes the total gastrectomy or the resection of the esophagus may be required. The adjacent lymph nodes should also be removed.
Chemotherapy may be necessary if the tumor cannot be resected or the operation is not enough. In some cases, chemotherapy is initiated in order to make the tumor smaller so that it can be operated. Radiotherapy may also be used as an adjuvant or palliative radiotherapy.
- Helicobacter pylori – a specific bacterium that thrives in the stomach is associated with an increased risk of developing stomach cancer, therefore, when this bacterium is detected, its eradication is recommended.
- In high-risk countries such as Japan, regular screening with endoscopy is performed. This helps to detect the tumor at asymptomatic stages and by thus improving the prognosis.
- Smoking cessation and a healthy diet are the cornerstones of cancer prevention.