Small bowel cancer

Disease Description (Causes and Symptoms)

• Definition and pathophysiology: Small bowel cancer is a rare malignant tumor arising in the small intestine (duodenum, jejunum, or ileum). Histological types include adenocarcinoma (most common), neuroendocrine tumors (carcinoid tumors), malignant lymphoma, sarcomas (e.g., GIST), and metastases from other organs. Invasiveness, patterns of metastasis, and symptoms vary depending on the tumor location and histological type.
• Main causes/risk factors:
  • Dietary factors: Increased consumption of red meat, smoked foods, salted foods, and saturated fat
  • Inflammatory bowel disease: Crohn’s disease
  • Malabsorption/autoimmune disease: Celiac disease
  • Genetic disorders: Familial adenomatous polyposis (FAP), Li-Fraumeni syndrome, neurofibromatosis, etc.
  • Radiation exposure, certain medications (estrogens and anabolic steroids), and environmental toxins
• Main symptoms:
  • Nonspecific: Weight loss, loss of appetite, fatigue (anemia)
  • Gastrointestinal symptoms: Abdominal pain, abdominal bloating/discomfort, vomiting (intestinal obstruction), symptoms of intestinal obstruction
  • Bleeding: Anemia due to gastrointestinal bleeding or melena/hematochezia
  • Symptoms due to complications: Intestinal perforation (acute abdominal pain, fever), jaundice (impaired bile drainage with lesions in the proximal duodenum)
  • Specific symptoms of carcinoid tumors (neuroendocrine tumors): Flushing of the face and chest, diarrhea, asthma-like symptoms (carcinoid syndrome)
• Diagnostic clues:
  • Blood tests: Anemia; in some cases, tumor markers (CEA may be elevated); in carcinoid tumors, elevated 5-HIAA (a urinary or blood metabolite)
  • Imaging/endoscopy: CT (CT enterography), capsule endoscopy, small bowel endoscopy/enteroscopy, computed tomography (to check for liver metastases)

Treatment Methods (Including Standard Treatment · Medications · Procedures/Surgery · Lifestyle Management) and Precautions

• Surgery
  • Curative resection (partial resection of the small intestine including the lesion) and regional lymph node dissection: Basic treatment for adenocarcinoma
  • Lesions in the proximal duodenum: Pancreaticoduodenectomy (Whipple procedure) may be considered
  • If emergency complications such as intestinal obstruction or perforation occur, partial resection may be performed to relieve symptoms
• Drug treatment and adjuvant therapy
  • Adenocarcinoma: Depending on the stage and procedure results, adjuvant chemotherapy may be considered; regimens similar to those used for colorectal cancer, such as FOLFOX/CAPOX, may be used
  • Neuroendocrine tumors (NETs): Somatostatin analogs (octreotide, lanreotide) to control symptoms; in advanced or refractory cases, molecularly targeted therapies such as everolimus and PRRT (177Lu-DOTATATE) may be considered
  • GIST (gastrointestinal stromal tumor): Imatinib is used as standard treatment for unresectable or metastatic disease and as adjuvant therapy. Later-line treatments include sunitinib and regorafenib
  • Malignant lymphoma: The main treatment is chemotherapy (e.g., CHOP); radiation therapy and surgery may be combined when necessary
• Radiation therapy: May be used as localized palliative treatment in some cases to control pain and bleeding
• Lifestyle management and supportive care
  • Blood transfusions/iron supplementation for anemia and bleeding, and nutritional management (supplementation for weight loss and malabsorption)
  • Symptom management: Pain control, treatment of vomiting and diarrhea, and somatostatin analogs for carcinoid syndrome
• Precautions and risk of complications
  • Because early symptoms are nonspecific, early diagnosis is necessary if weight loss, persistent abdominal pain, or changes in bowel habits occur
  • Malabsorption and malnutrition may occur after surgery → nutritional follow-up
  • Intestinal obstruction, perforation, severe bleeding, and distant metastases (such as to the liver) may occur
  • The indications for targeted therapy according to histological type must be confirmed (e.g., testing for KIT/PDGFRA mutations in GIST)

Checklist Before an Outpatient Visit (Items to Prepare, Points to Review, and Example Questions)

• Items to prepare (bring with you)
  • List of medications currently being taken (including prescription drugs, OTC medications, and nutritional supplements)
  • Copies of past medical records and surgical records, and recent test results (CT, endoscopy, pathology reports, etc.)
  • Records of weight changes and the timing and characteristics of symptoms (location and nature of pain, presence of bleeding, stool discoloration, etc.)
  • Family history (related to hereditary cancers)
• Information to check during the outpatient visit
  • Recent weight (kg), changes in food intake, changes in bowel habits, symptoms of anemia (dizziness and weakness)
  • Fever, jaundice, shortness of breath, or sudden severe abdominal pain (suspected perforation)
• Example questions for the outpatient visit (useful questions for patients to ask their doctor)
  • "How can you determine whether my current symptoms are caused by cancer or by another condition?"
  • "In what order will the tests (CT/endoscopy/capsule endoscopy) be performed?"
  • "Why do you recommend surgery, and what complications can be expected?"

Examples of General Questions to Ask the Doctor

• What is the histological type of this cancer (adenocarcinoma, NET, GIST, lymphoma, etc.)? Please explain the biopsy results (pathology report).
• What are the stage and prognosis? What are the expected benefits and side effects of each treatment option?
• What is the extent of surgery, and how likely is complete resection (the possibility of R0 resection)?
• Is adjuvant chemotherapy or targeted therapy recommended? What are the medication’s side effects and how can they be managed?

Examples of Disease-Specific Questions (1–2)

• Regarding adenocarcinoma: "How was the presence or absence of lymph node metastasis determined, and if lymph node metastasis is present, what is the additional treatment plan?"
• Regarding carcinoid tumors (NETs): "What are the results and significance of the urinary 5-HIAA test? How can symptoms of carcinoid syndrome (flushing and diarrhea) be controlled?"

(If necessary, bringing diagnostic materials (images and pathology reports) can allow for more specific consultation about the treatment plan.)