Intestinal Cancer Overview

Intestinal cancer originates in the small intestine, a tube-like organ that absorbs nutrients and carries digested food from the stomach to the large intestine. The small intestine has three sections: the duodenum near the stomach, the jejunum in the middle and the ileum near the large intestine. Most tumors develop in the duodenum or ileum.

Also known as small bowel cancer, intestinal cancer is less common than other gastrointestinal cancers, such as colorectal cancer. Overall, the condition is rare, accounting for less than 1% of new cancers diagnosed each year in the United States.

Intestinal Cancer Types

Small bowel cancer is classified based on the type of cells involved:

• Adenocarcinoma – Develops in the glandular cells in the intestinal lining (most common)
• Carcinoid tumor – Originates in the hormone-producing cells in the small intestine
• Gastrointestinal stromal tumor (GIST) – Forms in the interstitial cells of Cajal in the intestinal wall
• Lymphoma – Arises in the lymphatic tissues within the small intestine
• Sarcoma – Begins in the connective tissues of the intestinal wall, such as the muscles and blood vessels

Intestinal Cancer Causes and Factors

Small bowel cancer develops when the cells in the lining of the small intestine undergo harmful changes that cause them to grow and divide uncontrollably. The abnormal cells then build up, bind together and form tumors, which can potentially invade surrounding tissues or spread to other organs, such as the liver. The precise cause of the cellular mutations that lead to the development of small bowel cancer is unknown.

Known risk factors for intestinal cancer include:

• Chronic inflammatory conditions, such as Crohn’s disease, inflammatory bowel disease and celiac disease
• Inherited cancer predisposition syndromes, such as Lynch syndrome, familial adenomatous polyposis (FAP) and Peutz-Jeghers syndrome
• High-fat diet with excessive consumption of red or processed meats
• Weakened immune system
• Smoking and other forms of tobacco use
• Excessive consumption of alcoholic beverages

Intestinal Cancer Signs and Symptoms

Early symptoms of small bowel cancer are usually nonspecific, which can make the condition challenging to recognize. The first sign is often unexplained abdominal pain or discomfort, which may be intermittent or persistent.

What Does Intestinal Cancer Feel Like?

In addition to abdominal discomfort, small bowel cancer can cause:

• Abdominal fullness or bloating
• Nausea and vomiting
• Changes in bowel habits, such as persistent watery diarrhea
• Fatigue, weakness and general malaise

What Does Intestinal Cancer Look Like?

Usually, small bowel cancer does not cause noticeable external symptoms. The tumor may be visible in diagnostic images or during an endoscopic procedure, appearing as a mass or lesion on the lining of the small intestine. The tumor can also cause the intestinal walls to visibly thicken or create an obstruction. In advanced stages, small intestine cancer may also lead to noticeable physical changes, such as a palpable abdominal mass or signs of severe weight loss and malnutrition.

Intestinal Cancer Diagnosis

Small bowel cancer is usually diagnosed through a combination of medical history review, physical examination and diagnostic tests, such as:

• Imaging – Computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) scans can help a physician visualize the lining of the small intestine and detect abnormal growths.
• Endoscopy – A physician will insert a thin, flexible tube with a light source and miniature camera attached to the end (endoscope) into the mouth and guide it through the esophagus, stomach and duodenum. Using the light and camera, the physician will examine the interior of the small intestine for abnormalities.
• Biopsy – During an endoscopic procedure, a physician will take a small sample of abnormal tissue for microscopic examination by a pathologist, who can identify cancerous cells.
• Blood work – In a lab, a blood sample can be tested for certain markers that might indicate cancer.

The results of these diagnostic tests can help the physician identify the presence, location and extent of the tumor and guide treatment decisions.

Intestinal Cancer Stages

Like many types of cancer, small bowel cancer is staged using the American Joint Committee on Cancer (AJCC) TNM staging system, which considers the size of the primary tumor (T), the involvement of nearby lymph nodes (N) and the presence of distant metastasis (M). After assigning a value to each factor, a physician will evaluate the factors together to stage the tumor. Intestinal cancer stages range from 1 to 4, with higher numbers representing more advanced cancer.

Stage 1 Intestinal Cancer

At stage 1, the tumor is relatively small and remains confined to the innermost layers of the small intestine; it has not spread beyond the intestinal wall. Treatment for stage 1 intestinal cancer often involves surgical removal of the tumor. The prognosis is generally favorable, with a high likelihood of successful treatment.

Stage 2 Intestinal Cancer

At stage 2, the tumor has invaded the deeper layers of the intestinal wall but has not reached nearby lymph nodes; the cancer remains confined to the small intestine. Treatment usually involves surgical resection of the affected section of the small intestine, which may be followed by chemotherapy to help reduce the risk of recurrence. The prognosis for stage 2 intestinal cancer is generally favorable, especially with prompt and comprehensive treatment.

Stage 3 Intestinal Cancer

At stage 3, the tumor has spread beyond the small intestine to nearby lymph nodes but has not metastasized to distant organs. Typically, treatment involves surgical removal of the tumor and affected lymph nodes, followed by chemotherapy to target any remaining cancer cells and reduce the risk of recurrence. Although the prognosis for stage 3 intestinal cancer is more guarded than that for earlier stages, timely and comprehensive treatment can significantly improve the outcome.

Stage 4 Intestinal Cancer

At stage 4, the tumor has metastasized beyond the small intestine and nearby lymph nodes to distant organs, such as the liver or lungs. Treatment for metastatic intestinal cancer usually involves a combination of therapies, including surgery (if feasible), chemotherapy, targeted therapy and possibly radiation therapy. The goals are to manage symptoms, control cancer spread and improve quality of life.

Intestinal Cancer Treatment

The treatment options for small bowel cancer can vary based on the stage, size, location and extent of the tumor. A multidisciplinary approach tailored to the patient’s unique diagnosis is essential to achieve the best possible outcome and quality of life.

Surgery is often the primary treatment for localized, early-stage small bowel cancer. The goal is to eliminate the tumor and the affected portion of the small intestine. Chemotherapy may be administered after surgery to destroy any remaining cancer cells and help prevent a recurrence. Alternatively, chemo may be used as the main form of treatment for advanced-stage intestinal cancer.

Though not routinely used for small bowel cancer, radiation therapy may be considered to shrink a tumor and alleviate symptoms. Targeted therapies, which focus on the specific molecules involved in cancer growth, are sometimes used for treating advanced intestinal cancer.

Benefit from World-Class Care at TGH

Tampa General Hospital’s renowned Cancer Institute offers the latest options for diagnosing and treating all types of gastrointestinal cancer, including small bowel tumors. Our goal is to help each patient find the optimal treatment approach to ensure the best possible quality of life. In recognition of our consistently outstanding cancer outcomes, U.S. News & World Report has recognized TGH as One of the Nation's Best Hospitals for Cancer Care for 2024-25.

If you would like to learn more about intestinal cancer, contact TGH at (813) 844-7585 to request an appointment with an expert on our team.