(Disclaimer: This article is for scientific use only, and the information in the following content has been processed to protect patient privacy) Abstract: A 58-year-old patient had an untreated early duodenal bulb ulcer, which led to the progression of adenocarcinoma of the duodenal bulb with involvement of the distal stomach. After distal gastric resection, the patient’s symptoms disappeared, and the patient’s appetite was still acceptable at the 3-month postoperative follow-up, and there was no sign of tumor recurrence or metastasis by endoscopy for the time being. The patient and his family expressed their satisfaction with the treatment effect. Basic information】Male, 58 years old 【Disease type】Adenocarcinoma in the duodenal bulb 【Visiting hospital】The First Affiliated Hospital of Kunming Medical University 【Visiting time】 February 2021 【Treatment plan】Surgical treatment (distal gastrectomy) + medication (sodium omeprazole for injection + 5% glucose injection) + blood transfusion 【Treatment cycle】1 week of admission, regular follow-up 【Treatment effect】After surgery, the patient The patient recovered well and there was no sign of tumor recurrence or metastasis by endoscopic examination. The endoscopic examination showed that the mucosa of the duodenal bulb was obviously congested and edematous, and a small ulcer with white moss was seen on the mucosa of the posterior wall of the bulb, which was diagnosed as duodenal bulb ulcer and gastric retention. The night before last, the patient suddenly developed black stool without any obvious cause, and last night after dinner, he again developed persistent colic in the lower abdomen with nausea and vomit with fresh blood, and the abdominal pain was relieved after vomiting, but he developed palpitations, cold sweat, dizziness and weakness, so he came to the hospital. According to the patient’s condition, he was admitted to the hospital urgently for further examination. II. Treatment The patient was first treated with sodium omeprazole by injection and blood transfusion to stabilize the condition, and the fecal occult blood test turned negative after treatment. Endoscopic examination showed that the patient had abnormal retention of gastric juice in the fundus of the stomach, and the sinus of the stomach had florid changes with more mucus, peristalsis was still permissible, and the pylorus was congested. The patient was initially reluctant to undergo major surgery, but after thorough communication with the patient and his family, the patient finally agreed to undergo distal gastrectomy in order to ensure complete removal of the tumor and avoid its rapid spread, and the operation went smoothly and the patient returned to the ward safely. The patient returned to the ward safely. The tissue of the bulb of the tenth blood finger was preserved during the operation, and the diagnosis of adenocarcinoma in the bulb of the duodenum was confirmed by biopsy of the pathology department, which was moderately differentiated and considered to be primary duodenal adenocarcinoma invading the distal stomach. After surgery, the patient was given sodium omeprazole for injection to inhibit gastric acid secretion and protect the gastric mucosa. After regular and strict postoperative disinfection, drug exchange, and rehydration with 5% dextrose injection, the patient recovered well without complications such as secondary infection, gastrointestinal fistula, and gastric spasm, and was discharged 1 week after admission. At the follow-up visit 3 months after the operation, the patient was in a good mental state and had a fair appetite. There was no sign of tumor recurrence or metastasis by endoscopy for the time being, and the patient felt in a good state, but continued follow-up was needed. We are very glad to help the patient recover his health. Patients should fast for 48 hours after surgery. After fasting, patients should eat liquid food first, and then gradually transition to normal diet after the basic recovery of gastrointestinal function, and it is recommended that patients should mainly eat soft and easily digestible food, avoid cold, spicy and other stimulating food, and avoid high-fat and high-sugar diet to avoid adding burden to the gastrointestinal tract. 3. In the first six months after surgery, it is recommended that a review should be conducted once a month, and after six months, if the condition is stable, it can be changed to once every three months or six months according to the situation. The main symptoms are abdominal pain, bleeding, tarry stools and lumps, etc. Further diagnosis requires imaging and gastroscopy, and biopsy by gastroscopy is an important basis to confirm the diagnosis. Many patients think that ulcers do not become malignant, so they do not pay attention to them, but in fact, this is not the case, as the patient in this article was not treated in time for the first ulcer in the duodenal bulb, which led to cancerous ulcer and even spread to the stomach later. Surgery is the only means to cure the tumor. Early detection, early diagnosis and early treatment are the key to prognosis.