Small Intestine Carcinoma

Small intestine carcinoma is one of the rarest types of cancer affecting the digestive system, representing only 3% of gastrointestinal cancers in the United States. Despite its rarity, understanding its symptoms, risk factors, and treatment options is crucial for early detection and improved outcomes.

Table of contents

• What is small intestine carcinoma
• The small intestine and its parts
• Types of small intestine cancer
• Signs and symptoms
• Causes and risk factors
• Diagnosis and testing
• Treatment approaches
• Outlook and prognosis
• Living with small intestine cancer

What is small intestine carcinoma

Small intestine carcinoma, also called small bowel cancer, is a rare disease where cancer cells form in the tissues of the small intestine^[1]. The small intestine is part of your body’s digestive system, which also includes the stomach and large intestine. It is a long tube that connects your stomach to your large intestine^[3].

Small intestine cancer is extremely rare compared to other digestive system cancers. It makes up only 3% of gastrointestinal cancers in the United States^[1]. Cancers affecting the colon, rectum, esophagus, and stomach are much more common than those affecting the small intestine^[1].

The small intestine plays a vital role in your body. It removes and processes nutrients from the foods you eat, including vitamins, minerals, carbohydrates, fats, and proteins. It also produces hormones that help with digestion and plays a role in the body’s immune system, helping fight bacteria and viruses that enter through the mouth^[2].

The small intestine and its parts

• Duodenum
• Jejunum
• Ileum
• Stomach
• Large intestine

The small intestine is a long tube that folds many times to fit inside your abdomen. It consists of three distinct sections^[1]:

• Duodenum: The first section of your intestine near your stomach. It receives partially digested food from the stomach and adds digestive juices and bile to continue breaking down the food^[5].
• Jejunum: The middle section of your small intestine. This part breaks down food further and absorbs nutrients before passing digested food to the ileum^[5].
• Ileum: The last and longest section of your small intestine. It continues absorbing nutrients and passes what remains to the large intestine^[5].

Most small intestine cancer forms in either your duodenum or ileum^[1]. The location of the cancer within the small intestine can affect treatment decisions and outcomes.

Types of small intestine cancer

The different types of small intestine cancer are classified based on the type of cells where the cancer starts^[1]. Understanding which type of cancer you have is important because each type may require different treatment approaches.

Adenocarcinoma starts in glandular cells in the lining of the small intestine and is the most common type of small intestine cancer^[3]. About one-third of small intestine cancer cases are adenocarcinomas^[1]. Most of these tumors occur in the part of the small intestine near the stomach, and they may grow and block the intestine^[3].

Carcinoid tumors start in your neuroendocrine cells. These cells help your body produce hormones and control the release of digestive juices in your small intestine^[1]. A little less than half of small intestine cancer cases involve carcinoid tumors^[1].

Sarcomas start in connective tissues like your cartilage or muscle. The most common type of sarcoma that affects your small intestine is called a gastrointestinal stromal tumor (GIST)^[1]. A specific type called leiomyosarcoma starts in the smooth muscle cells of the small intestine, and most of these tumors occur in the part of the small intestine near the large intestine^[3].

Lymphoma starts in cells called lymphocytes. Lymphocytes are a type of white blood cell found in your lymphatic system, which is an essential part of your immune system that helps your body fight off abnormal cells or germs that may make you sick^[1].

Signs and symptoms

The symptoms of small intestine cancer vary depending on the type of tumor and where it’s located^[1]. Sometimes, tumors don’t cause any symptoms at all. For example, carcinoid tumors often don’t cause symptoms and may only be found during an imaging procedure for an unrelated issue^[1].

Common symptoms may include^[1][2]:

• Abdominal pain or cramps
• A lump in your abdomen
• Nausea, vomiting and diarrhea
• Unexplained weight loss
• Anemia (low red blood cell count)
• Jaundice (yellowing of your eyes or skin)
• Bloody stool (may appear red or black in the toilet)
• Flushed skin, especially purplish coloring on your arms and upper body
• Watery diarrhea
• Feeling very weak or tired

Early signs of small intestine cancer can include mild abdominal discomfort, slight changes in bowel habits, or occasional nausea^[1]. Unfortunately, because these symptoms are not specific and can be caused by many other conditions, they are often overlooked until the disease has progressed.

Causes and risk factors

Cancer cells form because of genetic mutations, or changes in a cell’s DNA, that cause it to multiply out of control. Researchers don’t know exactly what causes these changes to occur^[1]. Over time, cancer cells may break away from the original tumor and travel through your lymph nodes or blood to other places in your body where another tumor may form. This process is called metastasis^[1].

A risk factor includes anything that increases your chances of getting a disease. Not every person with one or more risk factors will develop small intestine cancer, and some people develop it without having any known risk factors^[3].

Risk factors for small intestine cancer include^[3][4]:

• Eating a high-fat diet
• Having Crohn disease, an inflammatory bowel disease that significantly increases risk^[6]
• Having celiac disease
• Having familial adenomatous polyposis (FAP), a genetic condition
• Having Lynch syndrome, a genetic condition that greatly increases cancer risk^[6]
• Smoking
• Alcohol consumption
• Obesity

Diagnosis and testing

Small intestine cancers are difficult to diagnose. For this reason, people suspected of having small intestine cancer often need multiple tests and procedures to locate the cancer or rule it out^[12]. Tests that examine the small intestine are used to diagnose and determine the extent, or stage, of the cancer^[3].

Procedures that create pictures of the small intestine and the area around it help diagnose small intestine cancer and show how far the cancer has spread. The process used to find out if cancer cells have spread within and around the small intestine is called staging^[4].

Diagnostic tests and procedures may include^[12]:

• Blood tests: These can’t detect small bowel cancer directly, but they can give clues about your health. A test called a complete blood count can detect a low red blood cell count if the cancer is causing bleeding. Blood tests also can show how well your organs are working, which might provide clues if cancer has spread^[12].
• Imaging tests: These create pictures of the body to show the location and size of the cancer. Tests might include MRI, CT, and positron emission tomography (PET scan)^[12].
• Biopsy: This is a procedure to remove a sample of tissue for testing in a lab. The tissue might be removed during a procedure to see inside the small intestine, or sometimes surgery is needed to get the sample. The sample is tested to see if it is cancer, and special tests give more details about the cancer cells^[12].

Several tests allow doctors to examine the inside of the small intestine. Which test you need depends on where in the small intestine your cancer is located. Options include upper endoscopy and other specialized procedures that use tools to collect tissue samples^[12].

Treatment approaches

Your healthcare team will create a treatment plan specific to your needs. The plan is based on your health and detailed information about the cancer^[11]. When deciding which treatments to offer, your healthcare team will consider the stage and location of the cancer, your age, your overall health, and what you prefer^[11].

Surgery is the main treatment for small intestine cancer that can be completely removed^[11][2]. The type of surgery depends on where the tumor is located in the small intestine. Your surgeon removes the cancer along with a clear border of tissue around it and the nearest lymph nodes^[11].

For cancer in the top of the duodenum, you might have a complex surgery called a pancreaticoduodenectomy, where the surgeon removes part of your pancreas and your gallbladder^[11]. Sometimes cancer can grow and completely block the bowel, requiring surgery to relieve symptoms or the placement of a tube called a stent to unblock the bowel^[17].

Chemotherapy uses anti-cancer drugs to destroy cancer cells. The drugs circulate throughout the body in the bloodstream^[11]. You might have chemotherapy after surgery to reduce the risk of cancer coming back, especially if your cancer began in the duodenum. Chemotherapy may also be used to reduce or control symptoms of cancer that has spread^[11].

Common chemotherapy regimens include fluorouracil (5FU), combinations like FOLFOX (folinic acid, fluorouracil and oxaliplatin), CAPOX (oxaliplatin and capecitabine), and FOLFIRI (folinic acid, fluorouracil and irinotecan)^[11].

Radiation therapy uses high-energy rays to destroy cancer cells^[11]. It isn’t used much for small bowel cancer but may be used before surgery to shrink the cancer or to treat cancer that has spread to control symptoms like pain^[2][17].

Targeted therapy and immunotherapy are newer treatment options that may be offered in certain cases for unresectable (cannot be completely removed) or recurrent small intestine cancer^[11].

Outlook and prognosis

Your outlook depends on numerous factors, including the cancer type, its stage, and where the tumor started in your small intestine^[1]. Early detection is vital, as it significantly expands treatment options and improves outcomes. The 5-year survival rate for early-stage small bowel cancer can reach up to 65%, while it drops to 42% at advanced stages^[1].

In order to plan treatment, it is important to know the type of small intestine cancer and whether the tumor can be removed by surgery^[3]. Certain factors affect your chance of recovery and treatment options, including how far the cancer has spread and your overall health^[3].

Small intestine adenocarcinoma is a rare malignancy of the gastrointestinal tract. However, these tumors are among those with the worst prognosis due to vague clinical signs and symptoms that lead to delays in diagnosis^[6][13].

Living with small intestine cancer

Living with small intestine cancer presents physical, practical, emotional and spiritual challenges^[20]. Recovery from treatment is different for each person and depends on the stage, the type of treatment, and many other factors^[20].

If the surgeon removes a large part of the small intestine to treat the cancer, there may not be enough tissue left for proper nutrient absorption. This condition is called short bowel syndrome^[20]. Symptoms include diarrhea, cramping, bloating, changes to stool appearance, heartburn, weakness and fatigue. Not getting enough nutrients can lead to weight loss, dehydration and malnutrition^[20].

Your healthcare team might suggest several ways to help manage short bowel syndrome^[20]:

• Vitamin and mineral supplements to reduce nutrient loss, including iron, magnesium, calcium and zinc
• Vitamin B12 injections if you develop anemia
• A high calorie diet with extra protein, carbohydrates and fats
• Eating small meals frequently
• Special sugar and salt liquids to treat dehydration
• Tube feeding or parenteral nutrition (liquid nutrients delivered through a vein) if you have trouble maintaining nutrition

Short bowel syndrome may improve over time as the remaining small intestine grows more inner lining to better absorb nutrients^[20].

Many people worry about cancer coming back after treatment. This fear is normal, but it’s important to focus on living, taking care of your health, and making the most of each day^[20]. Many people with small intestine adenocarcinoma are diagnosed when the cancer is very advanced, and there are programs and services available to help meet needs and improve quality of life^[20].