Gastric cancer is one of the most common malignant tumors in China, and the 2010 Health Statistical Yearbook shows that in 2005, the mortality rate of gastric cancer accounted for the 3rd place in the mortality rate of malignant tumors in China. The occurrence of gastric cancer is the result of the long-term effect of multiple factors. There are obvious regional differences in the incidence of gastric cancer in China, and environmental factors are dominant in the occurrence of gastric cancer, while host factors are subordinate. Studies have shown that H. pylori infection, diet, smoking and genetic susceptibility of the host are important factors affecting the occurrence of gastric cancer.
(I) Clinical manifestations
Gastric cancer lacks specific clinical symptoms, and early gastric cancer is often asymptomatic. The common clinical symptoms include discomfort or pain in the upper abdomen, loss of appetite, emaciation, weakness, nausea, vomiting, vomiting blood or black stool, diarrhea, constipation, fever, etc.
(B) Physical signs
Early stage or some locally progressive gastric cancer often has no obvious physical signs. In advanced gastric cancer, upper abdominal masses can be found, and in case of distant metastasis, corresponding signs may appear according to the metastasis site. In case of upper gastrointestinal perforation, bleeding or gastrointestinal obstruction, corresponding signs may appear.
(iii) Auxiliary examinations
1.Endoscopic examination
(1) Gastroscopy: It is a necessary examination means to confirm the diagnosis of gastric cancer, which can determine the location of tumor and obtain tissue specimens for pathological examination. If necessary, pigmented endoscopy or magnification endoscopy can be used as appropriate.
(2) Ultrasonic gastroscopy: It is useful for evaluating the depth of gastric cancer infiltration and judging the status of perigastric lymph node metastasis, and is recommended for preoperative staging of gastric cancer. This examination is necessary for those who intend to perform minimally invasive procedures such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD).
(3) Laparoscopy: For those who suspect peritoneal metastasis or intra-abdominal dissemination, laparoscopy can be considered.
2.Histopathological diagnosis
Histopathological diagnosis is the basis for confirming the diagnosis and treatment of gastric cancer. Patients diagnosed as invasive cancer by biopsy are subject to standardized treatment. If the depth of infiltration cannot be determined by biopsy pathology due to the limitation of biopsy sampling, patients who are reported as precancerous lesions or suspicious infiltration are recommended to repeat biopsy or combine with imaging results to further confirm the diagnosis and choose treatment plan.
3.Laboratory examination
(1) Blood tests: routine blood tests, blood biochemistry, serum tumor markers, etc.
(2) Urine, stool routine, fecal occult blood test.
4.Imaging examination
(1) Computed tomography (CT) scan: CT scan and enhanced scan are of great value in evaluating the extent of gastric cancer lesions, local lymph node metastasis and distant metastasis, and should be used as a routine method for preoperative staging of gastric cancer. In the absence of contraindications to the use of contrast agents, it is recommended that enhanced CT scan be performed in a well-filled gastric cavity. The scanning site should include the primary site and possible metastatic sites.
(2) Magnetic resonance imaging (MRI): MRI examination is one of the important imaging examinations. MRI can help determine the status of peritoneal metastases and can be used as appropriate.
(3) Upper gastrointestinal imaging: It is helpful to determine the scope and functional status of the primary gastric lesion, especially gas-barium double contrast imaging is one of the common imaging methods to diagnose gastric cancer. Water-soluble contrast agent is recommended for patients suspected of pyloric obstruction.
(4) Chest X-ray examination: it should include frontal and lateral phases, which can be used to evaluate whether there are lung metastases and other obvious lung lesions, and lateral phases can help to detect post-cardiac shadowing lesions.
(5) Ultrasonography: it is valuable for evaluating the local lymph node metastasis and superficial metastasis of gastric cancer, and can be used as a preliminary examination method for preoperative staging. Transabdominal ultrasonography can understand whether there are metastases in the abdominal cavity and pelvis of patients, especially ultrasonography can help identify the nature of lesions.
(6) PET-CT: It is not recommended for routine use. It can be used as appropriate for metastatic lesions that cannot be clearly identified by conventional imaging.
(7) Bone scan: It is not recommended for routine use. Bone scan can be considered for patients with gastric cancer suspected to have bone metastasis.