Intestinal Cancer

What intestinal cancer is

The intestines run from the stomach to the anus. The small intestine (duodenum, jejunum and ileum) is about 6 meters (20 feet) long and absorbs nutrients. The large intestine (colon and rectum) is about 1.5 meters (5 feet) long and absorbs water and forms stool.

Despite being much shorter, the large intestine accounts for about 95% or more of intestinal cancers. Colorectal cancer is the third most commonly diagnosed cancer in the US. Small intestine cancer makes up less than 1 in 20 digestive tract cancers.

Types of intestinal cancer

Cancer in the last part of the large intestine is rectal adenocarcinoma, which is treated somewhat differently from colon cancer because of the rectum's position in the pelvis.

Symptoms of intestinal cancer

Early cancer often causes no symptoms, which is why screening is so effective. When symptoms appear, they depend on where the tumor is.

Colon and rectal cancer

• Blood in the stool: bright red on the paper or mixed into stool, or dark stool
• A change in bowel habits lasting more than 3 weeks: looser, more frequent stools, constipation, or alternating
• A feeling of not fully emptying after a bowel movement (more typical of rectal cancer)
• Narrow, pencil-thin stools
• Lower belly pain, cramping or bloating
• Unexplained weight loss
• Tiredness and breathlessness from iron deficiency anemia, often the only sign of right-sided colon cancer

Small intestine cancer

• Cramping pain in the middle of the belly, often after eating
• Nausea and vomiting from partial blockage
• Dark or black stools, or anemia from slow bleeding
• Weight loss
• Yellowing of the skin and eyes if a tumor in the duodenum blocks the bile duct
• Flushing, diarrhea and wheezing (carcinoid syndrome) from neuroendocrine tumors that have spread to the liver

Can lower abdominal pain be intestinal cancer?

It can be, but it rarely is. Lower belly pain is far more often caused by constipation, irritable bowel syndrome, diverticulitis, urinary infection or menstrual and ovarian conditions. Pain points more toward cancer when it is persistent and comes with blood in the stool, weight loss, anemia, a change in bowel habits lasting weeks, or age over 50. The only way to tell for sure is to see a doctor, who may arrange a stool test or colonoscopy.

Causes and risk factors

Most colorectal cancers develop over 10 to 15 years from polyps, small growths on the bowel lining that gradually pick up genetic changes. Removing polyps prevents cancer.

Risk factors include:

• Age: most cases are over 50, though rates in younger adults are rising
• Family history of colorectal cancer or polyps in a parent, sibling or child
• Inherited syndromes: Lynch syndrome and familial adenomatous polyposis (FAP), which also raise small intestine cancer risk
• Inflammatory bowel disease: long-standing ulcerative colitis or Crohn's disease
• Celiac disease: raises the risk of small intestine lymphoma and adenocarcinoma
• Diet and lifestyle: red and processed meat, low fiber, alcohol, smoking, obesity, lack of activity
• Type 2 diabetes

Diagnosis

1. History and examination, including a rectal exam.
2. Blood tests: a full blood count for anemia, iron studies, and liver function.
3. Stool tests: a fecal immunochemical test (FIT) detects hidden blood and helps decide who needs urgent colonoscopy.
4. Colonoscopy: a camera examines the whole colon and rectum. Biopsies confirm cancer, and polyps can be removed during the same test.
5. Small bowel tests: capsule endoscopy (a swallowed pill camera), balloon-assisted enteroscopy, or CT or MR enterography.
6. Staging scans: CT of the chest, abdomen and pelvis, plus MRI of the pelvis for rectal cancer.
7. Tumor testing: for mismatch repair deficiency or microsatellite instability, and other gene changes that guide treatment and identify Lynch syndrome.

Stages run from 0 (very early, in the lining only) to IV (spread to distant organs such as the liver or lungs).

Treatment

• Surgery: the main treatment. The part of the bowel with the tumor and nearby lymph nodes is removed, and the ends are joined. Early tumors in polyps can sometimes be removed during colonoscopy. A temporary or permanent stoma (bag) is sometimes needed.
• Chemotherapy: after surgery for stage III colon cancer to reduce the chance of return, and for advanced disease.
• Radiotherapy: mainly for rectal cancer, often combined with chemotherapy before surgery.
• Targeted therapy: drugs that block blood vessel growth or specific gene pathways, used in advanced cancer. GISTs respond to tyrosine kinase inhibitors.
• Immunotherapy: very effective for tumors with mismatch repair deficiency.
• Liver or lung surgery: limited spread can sometimes still be removed with curative intent.

Outlook

Survival depends strongly on stage. When colorectal cancer is found while still confined to the bowel, about 9 in 10 people are alive 5 years later. Once it has spread to distant organs, the figure is much lower, although treatment has improved survival significantly. Small intestine cancer outlook varies widely by type: neuroendocrine tumors often grow slowly, while adenocarcinoma is often found later.

Screening and prevention

The US Preventive Services Task Force recommends colorectal cancer screening for average-risk adults aged 45 to 75. Options include:

• a FIT stool test every year
• a stool DNA-FIT test every 1 to 3 years
• colonoscopy every 10 years
• CT colonography every 5 years

People with a strong family history, IBD or inherited syndromes start earlier and are screened more often. Staying active, not smoking, limiting alcohol and processed meat, and eating plenty of fiber lower risk.

Frequently asked questions

What are the first symptoms of intestinal cancer?

Early intestinal cancer often has no symptoms. When they appear, the first signs are usually blood in the stool, a change in bowel habits lasting more than 3 weeks, tiredness from anemia, or vague belly discomfort. Small intestine cancer more often causes cramping pain after meals, vomiting or dark stools.

How can you tell if you have intestinal cancer?

You cannot tell from symptoms alone, because they overlap with common conditions like hemorrhoids and irritable bowel syndrome. A doctor will use a stool test, blood tests and usually a colonoscopy with biopsy. Anyone with persistent symptoms, especially over 50, should get checked rather than wait.

Is intestinal cancer the same as colon cancer?

Colon cancer is one type of intestinal cancer. Intestinal cancer includes cancers anywhere in the small intestine, colon or rectum. Most cases are colorectal, so the terms are often used interchangeably, but small intestine cancers behave and are treated differently.

Can young people get intestinal cancer?

Yes. Colorectal cancer is increasing in adults under 50, which is why screening now starts at 45. Younger people with rectal bleeding, persistent bowel changes or anemia should be checked rather than assuming hemorrhoids, especially with a family history.

Is intestinal cancer curable?

Often, yes. Colorectal cancer found at an early stage is cured by surgery in most people. Even some cancers that have spread to the liver can be cured with surgery and chemotherapy. Advanced cancer can usually be controlled for long periods with modern treatment.