Small intestine cancer

Small intestine cancer starts when cells in the small intestine start to grow out of control. The small intestine is the largest part of the gastrointestinal tract (GI tract), which processes food for energy and rids the body of solid waste. The small intestine is not as common as other cancers of the GI tract such as colon, rectal, stomach, and esophageal cancers in the United States. They account for fewer than 1 in 10 cancers in the GI tract, and fewer than 1 in 100 cancers overall. (American Cancer Society, 2023)

Small intestine cancer can be subdivided into duodenal cancer (the first part of the small intestine) and cancer of the jejunum and ileum (the latter two parts of the small intestine). Duodenal cancer has more in common with stomach cancer, while cancer of the jejunum and ileum have more in common with colorectal cancer. Five-year survival rates are 65%.

Experts believe that small intestine cancer develops much like colorectal cancer. It first begins as a small growth on the inner lining of the intestine (polyp), which over time becomes cancer. (American Cancer Society, 2023)

Approximately 50% of adenomas of the small intestine arise in the duodenum even though this location comprises only 4% of the length of the small intestine.  These adenomas occur mainly close to the ampulla of Vater, the outlet of the common bile duct from which bile acids are released. This area is also closely associated with the pancreas, so they are treated as pancreatic cancer.

The small intestine works by mixing food and gastric juices into a thick fluid in the stomach and then emptied into the small intestine. It then continues to break down and absorb the nutrients. Although it is referred to as the small intestine, it is the longest section of the GI tract being approximately 20 feet long. The length of the small intestine comprises 75% of the length of the entire gastrointestinal tract

There are three parts of the small intestine. The duodenum is the 1st section of small intestine and only about a foot long. The jejunum and ileum make up most of the small intestine. Most of the nutrients in food are absorbed into the bloodstream in these two parts. (American Cancer Society, 2023)

Histopathologic types

Subtypes of small intestine cancer include:
 Adenocarcinoma-This cancer begins in the gland cells that line the inside of the intestine. Adenocarcinomas account for about 1 in 3 small intestine cancers.
 Gastrointestinal stromal tumor-This type of cancer starts in connective tissues. The most common sarcoma in the intestine are gastrointestinal stromal tumors (GISTs)
 Lymphoma-These cancers start in lymphocytes.
 Carcinoid tumors of the midgut-This is a type of neuroendocrine tumor (NET). They tend to be slow growing and are the most common type of small intestine tumor. (American Cancer Society, 2023)
Most small intestine cancers (especially adenocarcinomas) develop in the duodenum. Cancers developed in the duodenum are often found at the ampulla of Vater. (American Cancer Society, 2023)

Risk factors

Risk factors for small intestine cancer include:

 Age: Cancer risk increases with age. The average age diagnosis is 65.(Cleveland Clinic, 2022)
 Race: In the U.S., small intestine cancer is slightly more common among people who identify as African Americans. Although lymphoma is more common among people who identify as white.(Cleveland Clinic, 2022)
 HIV/AIDS- treatments like radiation therapy may weaken your immune system and make you more susceptible to small intestine cancer. Drugs that suppress your immune system may also increase your risk.(Cleveland Clinic, 2022)
 Sex: Males are 25% more likely to develop the disease.(Cleveland Clinic, 2022)
 Diet: Various research has suggested that diets high in red meat and salted or smoked foods may raise the risk of small intestine cancer.(Cleveland Clinic, 2022). A human prospective study observed a markedly elevated risk for carcinoid tumors of the small intestine associated with dietary intake of saturated fat
 Crohn's disease
 Celiac disease
 Radiation exposure
 Hereditary gastrointestinal cancer syndromes: familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, Peutz–Jeghers syndrome
 Cholecystectomy, which alters the flow of bile to the small intestine, increases the risk of small intestinal adenocarcinomas, and this risk declines with increasing distance from the common bile duct .

Symptoms (Cleveland Clinic, 2022) 

 Abdominal pain
 lump on abdomen
 Nausea, vomiting and diarrhea
 Unexplained weight loss
 Anemia
 Jaundice
 Bloody stool

 Flushed skin, especially purplish coloring on arms and upper body

Treatments (Cleveland Clinic, 2022) 
The treatment received by a small intestine cancer patient depends on which type of cancer you have, the stage of the cancer, location of the tumor and personal preference could also be a factor in treatment decisions.

Surgery is the most common treatment. Resection is a type of surgery performed in order to remove all or part of an organ that contains cancer. Segments of the small intestine and nearby organ may also be removed if the cancer has spread. An anastomosis, which the cuts ends of the intestine together may also be performed. Lymph nodes near the small intestine may also be removed to be tested for signs of cancer spread.

Bypass may also be performed to allow food the ability to go around a tumor blocking the intestine but can not be removed.

Chemotherapy involves the use of drugs to stop the growth of cancer cells which in turn kills the cells or deprives them the to divide. Regional and systematic chemotherapy are the 2 treatments used.

Radiation therapy may be recommended by a doctor if the cancer can not be removed surgically. Radiation therapy uses high-energy X-rays to kill cancer cells or keep them from growing. It may also be administered alongside chemotherapy.

Immunotherapy boost the immune system so it is more capable of fighting cancer cells. This is recommended based on the type of gene mutations in a patients tumor.

Clinical trials are studies used to determine if new cancer treatments are safe, effective or better than standard treatments.

Survival rate (Cleveland Clinic, 2022) 
Survival rate varies between the types of small intestine cancers. 65% of individuals diagnosed with early-stage adenocarcinomas are alive five years later. The survival rate for later stages is much lower at 4%. Early-stage carcinoid tumors have a five-year survival rate of 95%, while later-stage cancers have a survival rate of 42%.

Additional images

References 
American Cancer Society. (2023). Key statistics for small intestine cancer. American Cancer Society. Retrieved April 3, 2023, from https://www.cancer.org/cancer/small-intestine-cancer/about/what-is-key-statistics.html 

Cleveland Clinic. (2022). Small intestine cancer: Symptoms, causes, Prognosis & Treatment. Cleveland Clinic. Retrieved April 4, 2023, from https://my.clevelandclinic.org/health/articles/6225-small-intestine-cancer 

Markman, M. (2022, July 20). Intestinal cancer: Causes, symptoms & treatments. Cancer Treatment Centers of America. Retrieved April 4, 2023, from https://www.cancercenter.com/cancer-types/intestinal-cancer 

Radhakrishnan, R. (2021, May 6). Is small intestine cancer curable? MedicineNet. Retrieved April 4, 2023, from https://www.medicinenet.com/is_small_intestine_cancer_curable/article.htm

External links 

Gastrointestinal cancer