All About Small Bowel Cancer
What is the small bowel?
The small bowel, also known as the small intestine, is the portion of the digestive tract that connects the stomach and the large bowel (colon). There are three distinct parts of the small bowel: 1) the duodenum, 2) the jejunum and 3) the ileum. (Note: Although these three parts can all be grouped under the term "small bowel," there are several notable differences between them, such as blood supply, degree of attachment, surrounding structures, etc).
In order to fit inside a person's body, the small and large intestines are folded up into a very compact form. However, if you were to unfold the small bowel and measure its full length, it would be about 15 to 20 feet long. In total, the small bowel makes up about 75% of the entire digestive system.
The small bowel plays a critical role in the breakdown and absorption of food, so that important vitamins, minerals, and nutrients can be absorbed into the body.
What is small bowel cancer?
Small bowel cancer occurs when cells in the small bowel begin to grow out of control. These cells can then invade nearby tissues and spread throughout the body. Large collections of cancer cells are called tumors. There are four main types of small bowel cancer, depending on the appearance of the cells under a microscope and the "cell of origin"(cell type in which the cancer starts):
- Adenocarcinoma: It typically starts in the lining or inside layer of the bowel, and usually occurs in the duodenum. Like adenocarcinomas of the colon or rectum, these tumors are thought to arise from a benign growth, known as an adenoma, in the small bowel. Adenocarcinoma of the small bowel is more common in males and occurs around 50-70 years of age. This type of small bowel cancer is more likely to be diagnosed at a late stage. People with Crohn's disease may present at an earlier age.
- Sarcoma: The typical subtype is leiomyosarcoma, which starts in the muscle wall of the small bowel and usually occurs in the ileum. One uncommon subtype is gastrointestinal stromal tumor (GIST), which can occur in any of the three parts of the small bowel.
- Carcinoid: Carcinoid tumors are a type of neuroendocrine tumor and they tend to occur in the ileum.
- Lymphoma: Small intestine lymphoma starts in the lymph tissue of the small bowel and usually occurs in the jejunum. The typical subtype is non-Hodgkin's lymphoma; more specifically MALT lymphomas, large B cell lymphoma, immunoproliferative small intestinal disease, and Burkitt’s lymphoma.
In some cases, small bowel cancer may actually be metastatic cancer, meaning that it has spread to the small bowel from a primary cancer site elsewhere in the body. In that case, it is treated as the primary cancer would be – if it has spread from the lung, it is treated as a lung cancer.
There are also several benign tumors that can arise from the small bowel including adenomas, leiomyomas, fibromas, and lipomas.
What causes small bowel cancer and am I at risk?
Despite being 75% of the digestive tract and 90% of the surface of the digestive tract, small bowel cancers account for only 1-2% of all gastrointestinal cancers. It is estimated that each year there are about 10,590 new cases of small bowel cancer diagnosed. It is more prevalent in African Americans and men.
The cause of most small bowel cancers is unknown. However, there are some risk factors that might increase a person's chance of developing small bowel cancer. Older age may also be a risk factor. Some studies have found an increased risk in those who smoke or drink alcohol. Those with Celiac disease may be at a higher risk for a small bowel lymphoma, called enteropathy-associated T-cell lymphoma, as well as have a higher risk of small bowel adenocarcinoma. Survivors of colon cancer also have a higher risk of developing small bowel cancer, as do those with Crohn’s disease.
There are also several genetic syndromes associated with a higher risk of developing small intestine adenocarcinoma. These include familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), Peutz-Jeghers syndrome (PJS), MUTYH-associated polyposis and Cystic Fibrosis (CF). Those with these genetic syndromes should consult with their healthcare team and a geneticist to better determine their risk for developing small bowel cancer and any screening needs.
Finally, immunosuppression associated with HIV/AIDS or organ transplantation can result in a higher risk of small bowel lymphoma.
How can I prevent small bowel cancer?
There are no known ways to prevent small bowel cancer. Since tobacco use is a potential risk factor for developing small bowel cancer, it is important to quit smoking or never start smoking. It is also important to eat a healthy diet, avoid drinking alcohol, and exercise regularly to reduce your cancer risk.
Those with FAP who have many polyps and are considered at especially high risk for developing small bowel cancer should consult with their healthcare team about the benefits of surgical intervention to remove parts of the small bowel/gastrointestinal system before cancer can develop.
What screening tests are available?
There are no routine screening tests available for small bowel cancer. Be sure to tell your healthcare provider if you have a history of any genetic syndromes so you can be closely monitored.
What are the signs of small bowel cancer?
Given how rare small bowel cancer is it can be difficult to diagnose. The symptoms of small bowel cancer are usually nonspecific and could be caused by a number of other health issues. It is important to talk to your provider about any symptoms you are experiencing.
Common symptoms include:
- Crampy abdominal (belly) pain.
- Blood mixed in the stools.
- Dark/tarry/black stools (from "digested" blood).
- Weight loss.
- Anemia, which is a lower than normal red blood cell count.
Again, these symptoms could be caused by a number of medical conditions. If symptoms such as the ones listed above are severe, worsening, or persistent, you should see your provider so that a timely and accurate diagnosis can be made. Anytime blood is in the stools or the stools are black, you should see your provider.
A far less common presenting symptom is bowel obstruction, in which the tumor blocks the passage of food products through the bowel. The blockage could be complete or partial. Bowel obstruction can cause sharp belly pain, sensation of abdominal bloating, vomiting, and constipation. In some cases, the bowel blockage can actually cause the bowel to suddenly rupture, leading to severe pain and shock (a dangerous drop in blood pressure). This is a medical emergency requiring surgery.
With carcinoid tumors, people can have watery diarrhea, flushing, wheezing and decreased blood pressure. Specific details on carcinoid tumors are provided in a separate article.
How is small bowel cancer diagnosed?
Your healthcare provider will take a complete medical history and do a full physical examination. They will likely order some blood tests, especially if you have had blood loss in the stool or diarrhea.
Additional tests to diagnose small bowel cancer can include:
- Stool sample to test for blood
- Endoscopy or colonoscopy looks inside the duodenum and the upper part of the jejunum (from above, through the throat and past the stomach) or the lower part of the ileum (from below). A biopsy can also be taken through the endoscope to confirm the diagnosis.
- Enteroscopy can be used to look at more of the small bowel but is more invasive and requires special equipment and training. There is also a pill with a small camera, which can be used to assess the bowel (capsule endoscopy). The pill is swallowed and then takes pictures periodically, which are sent wirelessly to a computer where they can be viewed.
- Barium x-rays, also known as small bowel follow-through, can be used. During this procedure, the patient first drinks barium liquid (which looks white on x-ray) and then gets abdomen x-rays to follow the passage of the barium through the entire small bowel. Enteroclysis, a special kind of barium study, which uses double contrast (both barium and methylcellulose) to get a better picture of the intestine can also be used. This technique can also be used with CT (CAT) scans.
- Radiology tests such as CT scans, ultrasound scans and other kinds of x-rays, which sometimes pick up a small bowel tumor, but more importantly look at other parts of the body to see if the cancer may have spread.
- MRI may be ordered if liver involvement is suspected, which can occur with carcinoid tumors.
These tests are used to guide the clinical diagnosis. They can identify a small bowel cancer about 50% of the time. The remainder are found through surgery. An actual pathologic diagnosis requires biopsy and microscopic evaluation of tissue from the suspected mass by a pathologist. However, it can be quite difficult to see - and then access - the tightly folded-up small bowel, and biopsies cannot always be done. In these cases, the pathologic diagnosis may have to be made as part of a surgical operation.
How is small bowel cancer staged?
In order to guide treatment and offer some insight into prognosis, small bowel cancer is staged. Healthcare providers use the TNM system (also called tumor - node - metastasis system). This system describes the size and local invasiveness of the tumor (T), which, if any, lymph nodes are involved (N), and if it has spread to other more distant areas of the body (M). This is then interpreted as a stage somewhere from I (one) denoting more limited disease to IV (four) denoting more advanced disease. Generally, the higher the stage, the more serious the cancer. The TNM breakdown is quite technical but is provided at the end of this article for your reference. Your healthcare provider will use the results of the diagnostic workup to assign the TNM result.
How is small bowel cancer treated?
This section focuses on the treatment of adenocarcinomas of the small bowel, as it is most common. Treatment varies somewhat based on the tumor type, size and location of the tumor, involvement of lymph nodes and metastasis.
The main treatment option for small bowel cancer is surgery to remove the tumor (excision) and to reconnect the remaining bowel (anastomosis). Surgery may also be needed for relief of a bowel obstruction. This can be done using an intestinal bypass when the obstructing tumor itself cannot be removed. The success of the surgery as a cure depends on the extent to which the surgeon can remove the entire mass during the operation. This depends on the location of the mass within the bowel as well as the amount of bowel that is involved.
In some cases, it could be necessary to remove part of the stomach, colon, the gall bladder or surrounding lymph nodes in order to do a more complete and effective surgery. The type of surgery used is largely dependent on the size of the tumor and its location.
Sometimes when a significant part of the bowel has to be removed in order to get the tumor out, there is not always enough bowel left over to reconnect. In these cases, the top end (proximal part) of the bowel is brought up to the wall of the abdomen and connected to a hole in the skin called a stoma. Attached to the stoma is a bag that is worn under one's clothes and collects the stool. This procedure is called an ileostomy and may be temporary or permanent.
Depending upon the extent of the surgery, special diets, vitamins, supplements, etc. may be needed to help with food digestion and absorption. Any such dietary changes post-surgery would likely be permanent. The surgical team and a dietitian will provide information about these changes if they are relevant to you.
Radiation treatment plays a smaller role then surgery in the management of small bowel cancers. In some cases, it can be used post-operatively if there is tumor left behind or if there are close surgical margins (the cancer cells were close to the edge of the tissue removed), to "clean up" any microscopic tumor cells. It may also be used to help palliate (relieve) symptoms from advanced disease, such as blood loss or pain from the tumor. Radiation therapy for bowel cancer is often given by external beam radiation.
Chemotherapy may be given either in combination with radiation therapy/surgery or by itself as a single treatment in select cases. Several chemotherapy medications have been used to treat small bowel cancer. However, given how rare small bowel cancer is, very few clinical trials have been completed showing the benefits of chemotherapy in the treatment of small bowel cancer. Some of the chemotherapy medications used in the treatment of small bowel cancer include capecitabine, oxaliplatin, fluorouracil, and irintotecan. Leucovorin can be used with fluorouracil to help it work better. These medications are typically used in combination. Chemotherapy may take a primary role in the treatment of small bowel cancers classified as lymphomas.
One use of non-standard oncologic therapy for this tumor is interferon. Interferon is a medication used for some types of small bowel cancers, typically carcinoids. This medication work by activating the body's immune system to fight the cancer.
There are clinical research trials for most types of cancer, and every stage of the disease. Clinical trials are designed to determine the value of specific treatments. Trials are often designed to treat a certain stage of cancer, either as the first form of treatment offered or as an option for treatment after other treatments have failed to work. They can be used to evaluate medications or treatments to prevent cancer, detect it earlier, or help manage side effects. Clinical trials are extremely important in furthering our knowledge of disease. It is through clinical trials that we know what we do today, and many exciting new therapies are currently being tested. Talk to your provider about participating in clinical trials in your area. You can also explore currently open clinical trials using the OncoLink Clinical Trials Matching Service.
Follow-Up Care and Survivorship
Once a patient has been treated for small bowel cancer, you will need to be closely followed for a recurrence. At first, you will have follow-up visits fairly often. The longer you are free of disease, the less often you will have to go for checkups. Your healthcare provider will tell you when he or she wants follow-up visits, and/or CT scans, depending on your case. It is very important that you let your healthcare provider know about any symptoms you are experiencing and that you keep all of your follow-up appointments.
Fear of recurrence, relationship issues, financial impact of cancer treatment, employment issues, and coping strategies are common emotional and practical issues experienced by small bowel cancer survivors. Your healthcare team can identify resources for support and management of these challenges faced during and after cancer.
Cancer survivorship is a relatively new focus of oncology care. With nearly 17 million cancer survivors in the US alone, there is a need to help patients transition from active treatment to survivorship. What happens next, how do you get back to normal, what should you know and do to live healthy going forward? A survivorship care plan can be a first step in educating yourself about navigating life after cancer and helping you communicate knowledgeably with your healthcare providers. Create a survivorship care plan today on OncoLink.
Resources for More Information
Cancer Care provides counseling, support groups, education, and financial assistance.
Imerman Angels provides you with one-on-one support through their cancer support community.
Appendix: Complete Small Bowel Cancer Staging
AJCC, Cancer Staging Manual, 8th Edition
Primary tumor cannot be evaluated
There is no evidence of a primary tumor
Carcinoma in situ / High grade dysplasia
Tumor invades the lamina propria or submucosa.
Tumor invades the lamina propria (innermost layer of the small bowel)
Tumor invades the submucosa
Tumor involves the muscularis propria
Tumor invades through the muscularis propria into the subserosa, or extends into nonperitonealized perimuscular tissue (mesentery or retroperitoneum) without serosal penetration
Regional lymph nodes cannot be evaluated
No regional lymph node metastasis
Involvement of 1-2 regional lymph nodes
Involvement of 3 or more lymph nodes
Distant metastasis cannot be evaluated
No distant metastasis
Distant metastasis present
T1 or T2
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