Small-Intestine Cancer: Patient Guide

This page is for people with small intestine cancer and the people helping them. It covers the different types, symptoms, tests, staging, treatment, and warning signs that need emergency care.

The small intestine is the longest stretch of the digestive tract, yet cancer starts there far less often than in the colon. The American Cancer Society projects 14,450 new cases in the United States in 2026, and 2,170 deaths. That is 0.7 percent of all new cancer diagnoses.

Two facts shape everything else. The organ is long, so parts of it are hard to reach with a scope.

Incidence is climbing. Age-adjusted rates rose an average of 2.3 percent per year over 2014 to 2023. The rate of new cases was 2.7 per 100,000 people per year for 2019 to 2023, and the median age at diagnosis was 66.

The first thing to get from your pathology report is the cell type, because the diseases behave differently and are treated differently.

• Adenocarcinoma. The most common. NCI puts it at roughly 25 to 50 percent of primary malignant tumors of the small intestine. Most occur in the duodenum, the first segment just past the stomach.
• Neuroendocrine tumors. About 20 percent of malignant lesions here. They occur more often in the ileum, the last segment, than in the duodenum or jejunum.
• Lymphoma.
• Sarcoma. Leiomyosarcoma is the most common one, and it turns up most often in the ileum.
• Gastrointestinal stromal tumors, usually called GISTs.

If your report says neuroendocrine tumor or GIST, the adenocarcinoma staging below may not apply to you. Ask which disease you actually have before reading further about treatment.

NCI lists these risk factors for small intestine cancer:

• Eating a high-fat diet.
• Having Crohn disease.
• Having celiac disease.
• Having familial adenomatous polyposis, known as FAP, an inherited condition that causes many polyps in the colon.

If you have Crohn disease, celiac disease, or FAP, tell any new gastroenterologist.

NCI lists these symptoms, which are easy to put off:

• Pain or cramps in the middle of the abdomen.
• Weight loss with no known reason.
• A lump in the abdomen.
• Blood in the stool.

None of those point clearly at the small bowel. See your doctor if you have any of these without a clear cause. Do not wait for them to settle on their own.

Tests used to look at the small intestine include:

• Capsule endoscopy. You swallow a capsule with a tiny camera that sends pictures of the inside of the small intestine.
• Double balloon endoscopy. A tube with inflatable balloons is used to look inside the small intestine.
• CT and MRI, for cross-sectional pictures of the tumor and any spread.
• Upper GI series with small bowel follow-through, which uses barium as a contrast agent.
• Biopsy, and sometimes laparotomy, meaning an operation to look inside the abdomen directly.

A biopsy removes cells or tissue so they can be checked under a microscope for cancer.

For adenocarcinoma, staging uses the AJCC TNM system. T describes how deep the tumor has grown through the bowel wall:

• T1a: invades the lamina propria, the layer just under the surface lining.
• T1b: invades the submucosa, the layer beneath that.
• T2: invades the muscularis propria, the muscle layer.
• T3: grows through the muscle layer into the subserosa or nearby tissue.
• T4: perforates the visceral peritoneum, the membrane covering the bowel, or invades other organs or structures.

N counts involved lymph nodes, and the cut point is three:

• N1: cancer in one or two regional lymph nodes.
• N2: cancer in three or more regional lymph nodes.

M1 means distant spread. Your team combines T, N, and M into an overall stage from 0 to IV. Ask them which stage you have and how many lymph nodes were examined.

Surgery is the core. NCI describes resection, meaning removal of the affected segment of bowel along with nearby tissue. When the tumor cannot be removed, a bypass may be done to route food around a blockage and relieve symptoms.

NCI lists radiation therapy, chemotherapy, and immunotherapy as other treatment types, and radiosensitizers (drugs that make tumor cells more sensitive to radiation) as being studied in clinical trials. NCI also says no standard effective chemotherapy exists for recurrent or metastatic disease, and recommends considering clinical trials.

Ask what specific operation is planned and what it removes.

SEER reports a 5-year relative survival of about 71.8 percent overall for small intestine cancer, based on people diagnosed between 2016 and 2022, with a clear gradient by extent of disease:

• Localized: 86.3 percent.
• Regional: 79.6 percent.
• Distant: 47.9 percent.

These figures pool all cell types together. They are averages, so your own outlook may differ. Ask your team what applies to you.

• You are vomiting repeatedly and passing no gas or stool, which can mean bowel obstruction.
• Your abdomen becomes swollen, hard, and severely painful.
• You vomit blood, or pass black tarry stools.
• You have a fever with severe abdominal pain.

• Which cell type is this, and does that change the whole plan?
• Which segment is it in: duodenum, jejunum, or ileum?
• How many lymph nodes were removed, and how many contained cancer?
• Should I have genetic counseling or testing, and should my relatives?
• Is there a clinical trial for this specific cell type?

• National Cancer Institute — Small Intestine Cancer Treatment (PDQ), Health Professional Version
• National Cancer Institute — Small Intestine Cancer Treatment (PDQ), Patient Version
• National Cancer Institute SEER Cancer Stat Facts: Small Intestine Cancer