Gardner syndrome

Gardner syndrome is an inherited condition that generates multiple polyps, or abnormal growths, on the inner walls of the colon and/or rectum. It is a type of familial adenomatous polyposis (FAP) that causes anywhere from a hundred to thousands of such polyps, also called adenomas.

Adenomas are made up of tissue that is similar to the colon’s lining, but they have distinct differences when viewed microscopically. With Gardner syndrome, adenomas may be benign (noncancerous) or malignant (cancerous). However, the disorder significantly increases the risk of colorectal cancer and other cancers.

While Gardner syndrome is a chronic disease, there are ways to manage the condition and to lower the risk of developing cancer.

Gardner syndrome symptoms

Though symptoms of Gardner syndrome are different for each individual, they may include:

• Dental abnormalities, such as extra or missing teeth
• Congenital hypertrophy of the retinal pigment epithelium, a typically asymptomatic and benign condition in which a pigmented lesion develops inside of the retina’s outer layer

Also, as with FAP, people with Gardner syndrome develop a great number of colorectal adenomas. Patients with this condition are also likely to have benign growths in the stomach, small intestine, adrenal glands, bone, skin and soft tissue. These may include:

• Epidermoid cysts: lump-like growths underneath or inside of the skin
• Fibromas: fibrous tumors of the connective tissue
• Desmoid tumors: fibrous tumors that can be located anywhere
• Osteomas: bone growths typically found on the jaw
• Polyps: found in the stomach or small intestine
• Masses: found in the adrenal glands
• Cancer: colorectal cancer as well as other cancers outside of the gastrointestinal organs

Gardner syndrome causes

Tumor suppressor genes help to prevent abnormal cell growth and division. In Gardner syndrome, there are mutations to the tumor suppressor gene APC. When these mutations happen, uncontrolled cellular growth occurs, resulting in the formation of polyps, tumors and cancer associated with Gardner syndrome. Exact symptoms depend on the specific area of the APC gene where the mutation is located.

Gardner syndrome is an autosomal dominant disease, meaning that a mutation only needs to be present in one copy of the APC gene in each cell. In other words, the condition may be inherited from just one parent. A person whose mother or father has the disorder has a 50 percent chance of developing it too, according to the Genetic and Rare Diseases Information Center (GARD).

It’s also possible, but less common, for the condition to result from spontaneous, uninherited changes to the APC gene.

Gardner syndrome and cancer: What's the connection?

In people with Gardner syndrome, colon polyps begin to form at about age 16, with 95 percent of those with the condition having polyps by age 35, according to the GARD. Because the polyps increase in number so rapidly, colon cancer almost always develops, usually between the ages of 34 and 43.

Other types of FAP-related cancer may occur, including:

• Stomach cancer
• Pancreatic cancer
• Thyroid cancer
• Small bowel cancer
• Liver cancer
• Bile duct cancer
• Adrenal gland cancer
• Central nervous system cancer

Gardner syndrome diagnosis

For those experiencing symptoms of Gardner syndrome, doctors may conduct genetic testing to identify any APC gene mutations. If the patient has a parent with the condition, it’s highly probable this testing will be done at an early age (colon screening is available at age 10 in patients whose family members have such mutations).

Diagnosis of Gardner syndrome is based on the presence of:

• More than 100 colon and/or rectal polyps, or fewer than 100 polyps in patients with a family history of FAP-related conditions, according to the GARD
• Osteomas
• Other tumors (including fibromas, desmoid tumors and epidermoid cysts)
• Related cancers

Diagnosis entails:

• Physical examination
• Colonoscopy
• X-ray of the jaw and/or long bones (tibia, fibula, femur, metatarsals and phalanges)

Gardner syndrome treatment

Treatment involves managing the condition, as well as measures to decrease the risk of cancer. This may involve:

• Physical examination: Starting in late adolescence, annual physicals and thyroid exams are performed.
• Screening tests: Patients who are positive for APC genetic mutations may undergo an annual (or biannual) colonoscopy or sigmoidoscopy (which is less invasive) beginning between the ages of 10 and 12. Additionally, screenings for hepatoblastoma, a type of liver cancer found in younger patients, and for desmoid tumors may be warranted.
• Esophagogastroduodenoscopy (EGD): Starting at age 25, this procedure is done every one to three years. It’s used to examine the esophagus, stomach and duodenum.
• Colectomy: This procedure to remove the colon is often recommended if the person has more than 20 to 30 colorectal polyps and/or fewer, more advanced polyps—with the aim of helping to prevent cancer from developing. Sometimes an NSAID (nonsteroidal anti-inflammatory drug) called sulindac is prescribed after the procedure to treat any remaining rectal polyps.

If a patient also has desmoid tumors, treatment may entail:

• Surgery to remove the tumor
• NSAIDS or anti-estrogen medications
• Chemotherapy and/or radiation therapy 
• Watchful waiting

If the patient has osteomas or epidermoid cysts, they may be removed surgically.