Gastric cancer is canceration of mucosal epithelial cells, and the most common site is the lesser curvature of the gastric antrum (gastric ulcers and gastric cancer are both on the lesser curvature of the gastric antrum)

Risk factors: Helicobacter pylori (Hp) infection (the main causes/risk factors of chronic gastritis, gastric ulcer, and gastric cancer are Hp) Precancerous lesions: gastric mucosal epithelial dysplasia (mild to moderate → treatment of the primary disease and follow-up gastroscopy; if severe → endoscopic mucosal resection/submucosal dissection) Precancerous diseases/conditions: atrophic gastritis, intestinal metaplasia, gastric ulcer, gastric adenoma, residual stomach (with certain risk of cancer) Among gastric polyps, adenomatous polyps have the highest canceration rate, and those with a diameter of ≥2cm are more likely to become larger (inflammatory polyps and hyperplastic polyps are less likely to become cancerous) Cancer pathogenesis: Hp infection → chronic non-atrophic gastritis → chronic atrophic gastritis → atrophic gastritis with intestinal metaplasia → dysplasia → carcinoma in situ → invasive cancer

early gastric cancer

Advanced gastric cancer

① The most common pathological type of gastric cancer → adenocarcinoma (most digestive system diseases are adenocarcinoma, because most of the digestive tract is glandular epithelium), except for the following three diseases: Esophageal cancer → squamous cell carcinoma, liver cancer → hepatocellular carcinoma, appendix → carcinoid ②Other types: squamous cell carcinoma, adenosquamous carcinoma, carcinoid, signet ring cell carcinoma (Signet ring cell carcinoma → The cancer cells are filled with mucus, and the cell nucleus is pushed to one end to resemble a ring. It is highly malignant)

① The most common way of metastasis of gastric cancer → lymphatic metastasis (cancer travels through lymph, sarcoma travels through blood) Transfer from near to far, but jump transfer can also occur Advanced gastric cancer often travels retrograde through the thoracic duct to the left supraclavicular lymph node (advanced lung cancer often metastasizes to the right supraclavicular lymph node) ② Hematogenous metastasis: the most common site → liver (gastrointestinal tumor metastasis is generally the most common in the liver, because the gastrointestinal vein flows into the liver through the portal vein) ③Direct infiltration: spread to surrounding tissues and organs (omentum, esophagus, liver, pancreas, transverse colon) ④Planting transfer: Implanted into the ovary → Krukenberg tumor (Krukenberg tumor), N years after gastric cancer surgery, palpable mass in the uterine appendage = Krukenberg tumor Implantation in the anterior rectal recess (rectometre recess in women/rectuvesical recess in men) → a palpable mass on digital rectal examination

T: depth of primary tumor invasion T1 → invades the lamina propria, muscularis mucosa, or submucosa T2→Infiltrate into the myometrium T3 → Infiltration into subserosal connective tissue T4a → invades the serosa; T4b → infiltrates adjacent organs

①The first choice and confirmatory examination for gastric cancer→gastroscopy and biopsy ②Commonly used examination methods for gastric cancer→Barium meal (mucosal disorder/interruption, irregular filling defect, in-contour shadow, gastric wall stiffness) ③Mainly used to determine preoperative clinical staging→CT/PET (to see metastasis) ④Discover clues of gastrointestinal malignant tumors and follow-up after surgery→CEA (carcinoembryonic antigen, a tumor marker with relatively high specificity for gastrointestinal tumors) ⑤ Determine the depth of invasion of gastrointestinal tumors → endoscopic ultrasound

Middle-aged and elderly people, long-term upper abdominal discomfort (or palpable mass in the upper abdomen), weight loss/anemia = gastric cancer Most early gastric cancers have no obvious symptoms; the common symptoms of advanced gastric cancer are weight loss and anemia.

The key to gastric cancer treatment → early diagnosis and early treatment, surgery is the first choice ① Endoscopic treatment (mainly used for intramucosal cancer without lymph node metastasis) → endoscopic mucosal resection/submucosal dissection ② Radical gastrectomy (for advanced gastric cancer without distant metastasis or metastasis to adjacent tissues) → The resection range should be more than 5cm from the edge of the tumor and lymph node dissection If the cancer is at both ends of the stomach (remove 3-4cm of the esophagus or duodenum to ensure there is no residue); lymph node dissection → lymph node dissection based on the extent of the affected lymph nodes ③ Extended radical gastrectomy for gastric cancer (used for liver, spleen, pancreas, and transverse colon involvement, but no distant metastasis) → remove most or all of the stomach and partially remove adjacent organs. ④Palliative surgery (used for distant metastasis and complications) → does not require clear tumor removal, only surgery to resolve complications (obstruction, perforation, bleeding)

After radical resection of early gastric cancer (tumor limited to mucosa and submucosa) → chemotherapy is generally not necessary After radical gastrectomy for advanced gastric cancer → Chemotherapy (fluorouracil, cisplatin) is required regardless of whether there is lymph node metastasis. Gastric cancer is not sensitive to radiotherapy.

①The key to preventing gastric cancer → eradicate Hp ②Precancerous lesions/diseases → mild or moderate dysplasia (follow-up gastroscopy to treat the primary disease) Severe dysplasia (endoscopic mucosal resection/submucosal dissection) Gastric polyps (especially adenomas, gastroscopy)