What Is Gastric Cancer?

Gastric cancer is a malignant tumor originating from the gastric mucosa epithelium. It has the highest incidence among various malignant tumors in China. There is a significant regional difference in the incidence of gastric cancer. The area is significantly higher. Incidence age is over 50 years old, and the ratio of male to female incidence is 2: 1. Due to changes in dietary structure, increased work pressure, and H. pylori infection, gastric cancer is becoming younger. Gastric cancer can occur in any part of the stomach, more than half of which occur in the antrum of the stomach, and the large curvature, small curvature of the stomach, and the anterior and posterior walls can be affected. Most gastric cancers are adenocarcinomas, with no obvious symptoms at the early stage, or non-specific symptoms such as epigastric discomfort and belching. They are often similar to the symptoms of chronic gastric diseases such as gastritis and gastric ulcers and are easy to be ignored. The rate is still low. The prognosis of gastric cancer is related to the pathological stage, location, tissue type, biological behavior, and treatment of gastric cancer.

Basic Information

English name: gastric carcinoma
Visiting department: Oncology
Multiple groups: Men over 50

Common locations: stomach
Common causes: Related to living environment, Helicobacter pylori infection, precancerous lesions, genetics and genes
Common symptoms: > 40 years old with upper abdominal pain, accompanied by anorexia and weight loss

Causes of gastric cancer

1. Regional environment and dietary factors

There are obvious regional differences in the incidence of gastric cancer. The incidence of gastric cancer is significantly higher in the northwest and eastern coastal areas of China than in the south. Long-term consumption of smoked and salted foods has a high incidence of distal gastric cancer, which is related to the high content of carcinogens or pre-carcinogens such as nitrites, mycotoxins, and polycyclic aromatic hydrocarbons in foods; the risk of gastric cancer in smokers 50% higher than non-smokers.

2. Helicobacter pylori ( Hp ) infection

The Hp infection rate in adults with high incidence of gastric cancer in China is above 60%. Helicobacter pylori can promote the conversion of nitrate to nitrite and nitrosamines and cause cancer; Hp infection causes chronic inflammation of the gastric mucosa and environmental pathogenic factors accelerate the excessive proliferation of mucosal epithelial cells, leading to aberrant carcinogenesis; toxic products of H. pylori CagA and VacA may have a cancer-promoting effect. The detection rate of anti-CagA antibodies in gastric cancer patients is significantly higher than that in the general population.

3. Precancerous lesions

Gastric diseases include gastric polyps, chronic atrophic gastritis, and remnant stomach after partial gastric resection. These lesions may be accompanied by varying degrees of chronic inflammatory processes, metaplasia or atypical hyperplasia of the gastrointestinal intestine, and may be transformed into cancer. Precancerous lesions refer to the histopathological changes of gastric mucosa that are prone to become cancerous. They are borderline pathological changes in the transition from benign epithelial tissue to cancer. Gastric mucosal dysplasia belongs to precancerous lesions. According to the degree of dysmorphism of the cells, it can be divided into three types: light, moderate, and severe. Severe dysplasia and well-differentiated early gastric cancer are sometimes difficult to distinguish.

4. Genetics and genes

Genetic and molecular biology studies have shown that relatives of gastric cancer patients with blood relatives have a 4 times higher incidence of gastric cancer than controls. Gastric cancer is a multi-factor, multi-step, multi-stage development process involving changes in oncogenes, tumor suppressor genes, apoptosis-related genes, and metastasis-related genes, and the forms of genetic changes are also diverse.

Classification of gastric cancer

1. Classification by general form

(1) Early gastric cancer refers to gastric cancer in which the cancer tissue is confined to the gastric mucosa and submucosa, and can be divided into raised, flat, and recessed types according to the naked eye shape.

(2) Progressive gastric cancer refers to gastric cancer that has infiltrated into the submucosa deeper than the submucosa. It can be divided into four types: polyp, local ulcer, invasive ulcer and diffuse invasive.

2. Histopathological classification

Can be divided into adenocarcinoma, adenosquamous carcinoma, squamous carcinoma, carcinoid, etc., the vast majority are gastric adenocarcinoma. According to different tissue structures, adenocarcinoma can also be divided into papillary carcinoma, tubular adenocarcinoma, poorly differentiated adenocarcinoma, mucinous adenocarcinoma and signet ring cell carcinoma. According to the degree of cell differentiation, it can be divided into three types: high differentiation, medium differentiation, and low differentiation. According to tissue origin, it can be divided into intestinal type and gastric type (diffuse type).

3. Classification by disease site

Can be divided into gastric fundus cardia cancer, gastric body cancer, gastric antrum cancer, etc., different parts of gastric cancer determine the different surgical procedures.

Clinical manifestations of gastric cancer

Most patients with early gastric cancer have no obvious symptoms, and a few have nausea, vomiting, or upper gastrointestinal symptoms similar to ulcers, which is difficult to attract enough attention. With the growth of tumors, more obvious symptoms appear when they affect gastric function, but they lack specificity.

Pain and weight loss are the most common clinical symptoms of advanced gastric cancer. Patients often have relatively clear upper gastrointestinal symptoms, such as epigastric discomfort, fullness after eating, as the disease progresses, abdominal pain worsens, appetite declines, and fatigue. Depending on the location of the tumor, there are special features. Cardiac gastric fundus cancer may have posterior sternum pain and progressive dysphagia; gastric cancer near the pylorus has pyloric obstruction.

When the tumor destroys the blood vessels, there may be symptoms of gastrointestinal bleeding such as vomiting blood and black stools; if the tumor invades the pancreatic capsule, continuous pain that radiates to the lower back; if the tumor ulcer perforates, it can cause severe pain or even peritoneal irritation; When hilar lymph node metastasis or compression of the common bile duct occurs, jaundice can occur; when distant lymph node metastasis, the enlarged lymph node can be touched on the left clavicle.

Patients with advanced gastric cancer often have symptoms of anemia, weight loss, malnutrition, and even cachexia.

Gastric cancer metastasis pathway

The spread and metastasis of gastric cancer are as follows:

Direct infiltration

Cardiac gastric cancer easily invades the lower end of the esophagus, and gastric cancer can invade the duodenum. Gastric cancer with poorly differentiated and invasive growth breaks through the serosa and easily spreads to adjacent organs such as the omentum, colon, liver, and pancreas.

2. Hematogenous metastasis

Occurs in advanced stages, when cancer cells enter the portal vein or systemic circulation and spread to other parts of the body, forming metastases. The most common metastatic organs are liver, lung, pancreas, bone, etc., with liver metastasis being the most common.

3. Peritoneal implant transfer

When gastric cancer tissue infiltrates the serosa, tumor cells fall off and are planted on the peritoneum and organ serosa, forming metastatic nodules. Peritoneal implantation is most likely to occur in the upper abdomen and on the mesentery. Implants in the rectum and bladder are signs of advanced gastric cancer. Metastatic rectal cancer can be found by digital rectal examination. Ovarian metastatic tumors can occur in women with gastric cancer.

4. Lymphatic metastasis

It is the main metastasis pathway of gastric cancer. The lymphatic metastasis rate of advanced gastric cancer is about 70%. Early gastric cancer may also have lymphatic metastasis. There is a positive correlation between the lymph node metastasis rate of gastric cancer and the depth of invasion of cancerous foci. Lymph node metastasis of gastric cancer is usually gradual and gradual, but jumping lymphatic metastasis can also occur, that is, there is no metastasis in the first station and metastasis in the second station. End-stage gastric cancer can be metastasized to the left supraclavicular lymph node via the thoracic duct, or to the umbilicus via the hepatic round ligament.

Gastric cancer examination

1. X- ray barium meal inspection

The application of digital X-ray gastrointestinal angiography is still a common method for the diagnosis of gastric cancer. A gas-barium double contrast is often used to make a diagnosis by observing the mucosal and filling phases. The main change of early gastric cancer is the abnormality of the mucosal phase. The morphology of advanced gastric cancer is basically consistent with the general classification of gastric cancer.

2. Fiber gastroscopy

Directly observing the location and extent of gastric mucosal lesions, and obtaining the tissues for pathological examination are the most effective methods for diagnosing gastric cancer. The use of a fiber gastroscope with an ultrasound probe for ultrasound imaging of the diseased area helps to understand the depth of tumor invasion and the surrounding organs and lymph nodes for invasion and metastasis.

3. Abdominal ultrasound

In the diagnosis of gastric cancer, abdominal ultrasound is mainly used to observe the infiltration and lymph node metastasis of the adjacent organs of the stomach (especially the liver and pancreas).

4. Spiral CT and Positron Emission Imaging

Multi-slice spiral CT scan combined with three-dimensional stereo reconstruction and simulated endoscopy is a new non-invasive examination method, which is helpful for the diagnosis and preoperative clinical staging of gastric cancer. Utilizing the affinity of gastric cancer tissue for fluorine and deoxy-D-glucose (FDG), using positron emission imaging (PET) technology can determine the status of lymph nodes and distant metastatic lesions with high accuracy.

5. Tumor markers

Serum CEA, CA50, CA72-4, CA19-9 and other tumor-associated antigens can be increased, but the sensitivity and specificity are not high, which is helpful to judge the tumor prognosis and the efficacy of chemotherapy.

Gastric cancer diagnosis

Medical history, physical examination, and laboratory tests are consistent with the characteristics of gastric cancer, and X-ray gas-barium double angiography or endoscopic findings of space-occupying lesions can clinically diagnose gastric cancer, but the final diagnosis of gastric cancer must be based on the results of biopsy or cytology. In the following cases, conduct a comprehensive inspection in a timely manner:

1. Patients with gastric ulcer who have not undergone strict improvement after strict medical treatment;

2. Those who have discomfort or pain in the middle and upper abdomen after the age of 40, without obvious rhythm, accompanied by obvious lack of appetite and weight loss;

3. Those over 40 years old with previous chronic atrophic gastritis or atypical hyperplasia, and recent symptoms have worsened;

4. Have a previous history of chronic stomach disease, fecal occult blood test, found positive fecal occult blood, lasting more than 2 weeks;

5. Stomach polyps greater than 2cm.

After obtaining a qualitative diagnosis of gastric cancer through gastroscopy and biopsy, a series of imaging examinations are needed to carry out the staged diagnosis of gastric cancer (TNM staging). Accurate staging is very important to formulate a reasonable treatment plan, judge the prognosis, and evaluate the curative effect. TNM staging mainly describes the invasion depth (T), lymph node metastasis (N), and distant metastasis (M) of primary gastric cancer lesions, and then determines the total stage according to the combination of different stages of T, N, and M (0, ). Stage ), the higher the stage, the later the disease, and the shorter the survival time.

Gastric Cancer Treatment

Surgical treatment

(1) Radical surgery The principle is to remove a part or all of the stomach including cancerous foci and the invaded stomach wall in one piece. According to the clinical staging standard, the lymph nodes around the stomach are removed in one piece, and the digestive tract is reconstructed.

(2) Palliative surgery The primary focus cannot be removed. Surgery performed to reduce symptoms caused by complications such as obstruction, perforation, and bleeding, such as gastric jejunostomy, jejunostomy, and perforation repair.

2. chemotherapy

It is used before, during and after radical surgery to prolong survival. Adequate chemotherapy for patients with advanced gastric cancer can slow the development of tumors, improve symptoms, and have some short-term effects. In principle, adjuvant chemotherapy is not necessary after radical gastric cancer radical surgery. Adjuvant chemotherapy should be performed in the following cases: the pathological type is highly malignant; the area of the cancerous lesion is larger than 5 cm; multiple cancerous lesions; and the age is less than 40 years. Recurrence of advanced gastric cancer requires radical chemotherapy, palliative surgery, and recurrence after radical surgery.

Commonly used gastric cancer chemotherapy routes include oral administration, intravenous, peritoneal, and arterial intubation. Commonly used oral chemotherapeutic drugs are tegafur, eufuridine, and flutlon. Commonly used intravenous chemotherapy drugs include fluorouracil, mitomycin, cisplatin, adriamycin, etoposide, calcium formyltetrahydrofolate and the like. In recent years, new chemotherapeutics such as paclitaxel, platinum oxalate, topase inhibitors, and Xeloda have been used in the treatment of gastric cancer.

3. Targeted therapy

Targeted therapy can specifically damage cancer cells and reduce normal cell damage. At present, the types and effects of targeted therapies for gastric cancer are limited. Targeted therapy drugs include epidermal growth factor receptor inhibitors, angiogenesis inhibitors, cell cycle inhibitors, apoptosis promoters, and matrix metalloproteinase inhibitors.

4. Other treatments

Immunotherapy for gastric cancer includes non-specific biological response modifiers such as BCG, lentinan, etc .; cytokines such as interleukin, interferon, tumor necrosis factor, etc .; and adoptive immunotherapy such as killer cells (LAK) after lymphocyte activation, tumor infiltrating lymph Cells (TIL) and other clinical applications. Anti-angiogenesis genes are a well-researched gene therapy method and may play a role in the treatment of gastric cancer.

5. Supportive treatment

It aims to alleviate patient suffering, improve quality of life, and prolong survival. Including analgesia, correcting anemia, improving appetite, improving nutritional status, alleviating obstruction, controlling ascites, psychological treatment, etc.

Gastric cancer prognosis

The prognosis of gastric cancer is related to the pathological stage, location, tissue type, biological behavior, and treatment of gastric cancer. Early gastric cancer has a better prognosis after treatment. Cardiac cancer and proximal gastric cancer of the upper 1/3 have a worse prognosis than gastric body and distal gastric cancer. Women have a better prognosis than men. Patients with gastric cancer over 60 years of age have good postoperative results, and their prognosis is poor under 30 years of age.

Gastric cancer prevention

1. Change the diet structure, eat more vegetables, fruits, legumes and milk, fresh fish, meat, eggs. Promote the consumption of garlic and green tea.

2. Change bad eating habits, avoid overeating, irregular meals; eat too fast, too hot or too hard; eat less smoked and pickled foods, avoid high salt diet

3. Drink less alcohol and do not smoke.

4. Do a good job of preventing mildew and mildew in food to protect the hygiene of drinking water.

5. Actively treat gastric ulcer, chronic gastritis, and treat Helicobacter pylori infection in the stomach.

6. General screening of gastric cancer in high-risk areas and high-risk populations.

Early gastric cancer recognition

In July 2018, Japanese researchers developed a method for identifying gastric cancer with the help of artificial intelligence technology, which can detect early gastric cancer with high accuracy ^[1] .