A gastrointestinal (GI) polyp is an abnormal growth of tissue that projects from the inner lining of the colon, rectum, stomach, or other parts of the digestive (or GI) tract. Polyps may be noncancerous (benign), cancerous (malignant), or precancerous, meaning they may become cancerous. When numerous polyps are present, rather than just one or a few, doctors refer to it as polyposis.

A number of syndromes, collectively known as GI polyposis syndromes, are characterized by the presence of numerous polyps—sometimes hundreds or thousands—in the colon, rectum, and/or other parts of the GI tract. In many cases, the polyps develop at a young age, and people with a GI polyposis syndrome are at increased risk for colorectal cancer and, sometimes, stomach cancer or cancers in other parts of the body.

Because of the increased risk of cancer and young age of onset, those with a polyposis syndrome typically get colonoscopies at a younger age and more frequently than usual. Treatment may also involve surgical removal of the colon and rectum and regular screenings for cancer in other parts of the body. Also, because polyposis syndromes can also cause symptoms in other parts of the body, such as the skin, teeth, and bones, among others, treatment may involve multiple medical specialists.

“Polyposis syndromes often have very distinct and unique features,” says Xavier Llor, MD, PhD, co-director of the Gastrointestinal and Pancreatic Cancer Prevention Program. “A multidisciplinary approach that includes different clinical specialties is essential to provide the best care for patients with these conditions. With proper care, risks to these patients can be minimized and they can have an excellent prognosis.”

As noted above, many polyposis syndromes are caused by mutations in certain genes. These mutations can alter the function of the affected genes, resulting in an increased risk of developing colorectal polyps and, for many polyposis syndromes, conditions that affect other parts of the body.

In some cases, polyposis syndromes occur sporadically, meaning the affected individuals did not inherit the condition from their parents. Often, sporadic cases of polyposis occur when there is a new mutation in a gene related to one of the polyposis syndromes.

Symptoms may vary depending on the type of polyposis syndrome and patients may initially not have any symptoms. Symptoms related to colorectal and GI polyposis may include:

• Rectal bleeding
• Blood in stool
• Anemia
• Weight loss
• Nausea and/or vomiting
• Abdominal pain
• Diarrhea
• Constipation
• Tenesmus (the feeling of having to pass stools even though the bowels are empty)
• Protein-losing enteropathy (excess loss of proteins in the blood into the GI tract, leading to limb swelling, fluid buildup in the abdomen, and diarrhea)

The polyposis syndromes often cause symptoms in other parts of the body, as noted above.

Diagnosis of polyposis syndromes may involve a review of the patient’s medical history, a physical exam, and one or more procedures or tests. A doctor may suspect a patient has a polyposis syndrome based on their family history, the presence of symptoms and signs that could be caused by a polyposis syndrome, or if multiple colorectal polyps are found during colonoscopy.

If a doctor suspects a patient may have a polyposis syndrome, they may begin to make a diagnosis by asking whether the patient has a family history of colorectal cancer or a polyposis syndrome, what symptoms—if any—are present, and when they began.

During the physical exam, the doctor will look for signs that could indicate a polyposis syndrome. For instance, they may check the skin for freckling, cysts, dental abnormalities, fingernail and toenail thinning, or separation from the nailbed.

Certain tests and procedures are also used to identify and diagnose polyposis syndromes, including:

• Colonoscopy and/or sigmoidoscopy. These procedures are used to examine the inside of the rectum and colon. If polyps are detected during the exam, they can be removed and then analyzed in a lab to determine whether the tissue is abnormal or cancerous. In a colonoscopy, the provider examines the rectum and the entire colon, whereas in a sigmoidoscopy, the rectum and only the lower part of the colon (called the sigmoid colon) are examined.
  
  Often, doctors will suspect a polyposis syndrome if 10 or more colorectal polyps are detected over time, multiple polyps are found in other parts of the GI tract, or if polyps are found in a young person with a family history of polyposis.
  
• Upper endoscopy. In this procedure, a scope is inserted into the mouth, down the throat, then into the esophagus, stomach, and duodenum. Upper endoscopy is used to look for polyps or other abnormalities in the upper digestive tract. As with colonoscopy and sigmoidoscopy, if polyps are detected, they can be removed for laboratory analysis.
  
• Genetic testing. Genetic testing checks for gene variants associated with polyposis syndromes. A gene panel test that checks for variants in multiple genes known to be involved in polyposis syndromes may be used.
  
  If a polyposis syndrome-associated gene mutation is found, other family members should also undergo genetic testing to determine if they have the same gene mutation.

The outlook for people with a polyposis syndrome varies based on the type of syndrome, its severity, and the timing of diagnosis and treatment. The polyposis syndromes are associated with an increased risk for colorectal cancer and, depending on the specific syndrome, cancers and/or conditions that affect other parts of the body.

In general, the outlook is improved for those who receive an early diagnosis. With active surveillance and timely treatment, people may prevent the onset of colorectal cancer. Periodic cancer screenings can help health care providers detect cancers in other parts of the body at early stages of disease, when it may be easier to treat.

“Yale’s Gastrointestinal and Pancreatic Cancer Prevention Program through its Lynch Syndrome and Polyposis Clinic and Pancreas Cancer Early Detection Clinic take a comprehensive approach to polyposis syndromes, offering state-of-the-art diagnosis, risk assessment, surveillance, and prophylactic measures,” says Yale Medicine gastroenterologist Benjamin Lerner, MD, MHS. “We also collaborate and advise clinicians who care for these patients outside of our program.”