Research suggests that cancer accounts for almost 12% of total deaths worldwide. Gastric cancer is one of the most common types of cancer, ranking fourth in overall frequency and accounting to a large number of deaths each year.
Cancer is a life threatening condition which occurs when the cells in the human body start to grow uncontrollably. Cancer cells don’t behave like normal cells in three ways:
- Mutation in the gene causes the cells to grow quickly and live longer. Normally cells grow, divide to grow new cells, and die when becomes old or damaged. But cancer cells unnecessarily make new cells and doesn't die when they become old and damaged.
- Cancer cells grow to its nearby tissues.
- Unlike normal cells, cancer cells move to other parts of the body and form secondary tumors while replacing normal cells.
Gastric cancer is a type of cancer that begins from the inner lining of the stomach and later spreads from the stomach to other parts of the body such as the liver, lungs, bones, and lymph nodes. Gastric cancer is categorized into two variants - intestinal and diffuse. The intestinal type occurs due to inflammation that progresses from chronic gastritis to atrophic gastritis and finally to intestinal metaplasia and dysplasia. On the other hand, a diffuse type is characterized by the development of linitis plastic which occurs when gastric cancer is left untreated or undiagnosed and reaches the advanced stage.
Symptoms of Gastric cancer
Most often the symptoms of gastric cancer are either asymptomatic, that is producing no noticeable symptoms or nonspecific symptoms, that is symptoms associated with stomach or symptoms of related or unrelated disorders. Some of the early symptoms of gastric cancer may include:
Stages of gastric cancer
Gastric cancer is divided into four stages:
Stage 0 - It is the beginning of the development of gastric cancer and at this stage, cancer is limited to the inner lining of the stomach. If diagnosed, it can be treated without chemotherapy or radiation.
Stage 1 - In this stage, gastric cancer is penetrated to a second or third layer of the stomach and to nearby lymph nodes.
Stage 2 - Penetration to the second layer and more distant lymph nodes. For treatment, it sometimes needs neoadjuvant chemotherapy.
Stage 3 - Penetration to the third and fourth layer of the stomach with more distant lymph nodes. A cure at this stage is only possible in some cases.
Stage 4 - This is the last stage of gastric cancer and in this stage, cancer has spread to nearby tissues and more distant lymph nodes or has metastasized to other organs. A cure at this stage is rarely possible.
Risk factors for gastric cancer
1. Helicobacter pylori infection
Helicobacter pylori infection is the most common disease that contributes to the development of gastric cancer. Helicobacter pylori is a bacteria that is found in the gastric mucous layer or to the epithelial lining of the stomach. Helicobacter pylori are more likely to be acquired in childhood.
It causes some degree of persistent inflammation in the mammalian stomach. Helicobacter pylori are believed to be an essential risk factor in 60% to 80% of all gastric cancers and the primary mechanism by which this infection causes gastric cancer is chronic inflammation.
Evidence suggests that Helicobacter pylori infection plays an important role in the remodeling of tissues, angiogenesis, tumor invasion, and metastasis. It also induces various genes in the host cells that acts as a potential determinant of inflammation, angiogenesis, and metastasis.
2. Tobacco consumption and smoking
Tobacco consumption or cigarette smoking is considered to be a major risk factor for the development of many types of cancer, including gastric cancer. Although the exact mechanism that explains the relationship between tobacco consumption and the development of gastric cancer is unknown, it is strongly correlated to it. Cigarette smoking may cause reduction of the circulating epidermal growth factor which increases free radical production in gastric mucosa.
Another possible mechanism is that tobacco consumption causes high damage in the body that affects the cells and its functioning. According to research, many patients who are being diagnosed with gastric cancer are found to be heavy smokers. It widely depends on the number of cigarettes smoked per day and also the duration an individual is involved in tobacco consumption and cigarette smoking. Chemicals present in them are responsible for the damage they cause in the body.
3. Consumption of alcohol
Excessive consumption of alcohol also acts as a risk factor for gastric cancer. There are various mechanisms that can explain how alcohol develops gastric cancer. One of the mechanism includes chronic alcohol consumption disturbs gastric mucosal barrier by inhibiting COX 1 receptor enzymes which reduce the production of cytoprotective prostaglandin.
Also, research suggests that chronic alcohol consumption is associated with the occurrence of Helicobacter pylori infection, which is a most common infection that contributes to gastric cancer.
Evidence suggests that high body mass index or accumulation of fat in the body could lead to the occurrence of gastric cancer. Obesity increases the risk of gastric cancer by contributing to the development of gastroesophageal reflux disease, which increases the risk of gastric cancer. Gastroesophageal reflux disease is a disease which occurs when acid in the stomach flows back to the tube that connects the mouth and stomach.
Extra fat in the body can cause extra pressure on the stomach and on the lower esophageal sphincter. A person suffering from gastroesophageal reflux disease is two times more likely to suffer from gastric cancer.
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