How Gardner syndrome leads to colon cancer, skin bumps, extra teeth and more

Gardner syndrome is a rare, inherited condition where people develop hundreds and sometimes thousands of abnormal growths in their large and small intestines.

These growths, called polyps, are noncancerous at first, but some have an almost 100% chance of becoming cancerous. This means that people with Gardner syndrome will almost certainly develop colorectal cancer.

“The chance that a polyp will turn into cancer is normally very small,” explains Eduardo Vilar-Sanchez, M.D., Ph.D. “But because Gardner syndrome patients have so many polyps, the odds that some will become cancerous skyrockets.”

It’s like buying lottery tickets, he says.

“Purchasing hundreds or thousands of tickets, instead of just a few, increases your likelihood of winning.”

We asked Vilar-Sanchez, who treats patients with Gardner syndrome in MD Anderson’s Gastrointestinal Cancer Center, more about this unusual syndrome that affects only 1 out of every million people.

What causes Gardner syndrome?

Gardner syndrome is caused by mutations in a gene named APC. A normal APC gene keeps cell growth in check by making sure cells don’t multiply too quickly. But when an APC gene mutates, cells grow out of control. They clump together and form abnormal growths. Most of these growths occur in the bowel, but some affect other areas of the body as well.

What types of symptoms does Gardner syndrome create?

The most common feature of Gardner syndrome is the presence of multiple polyps in the lining of the intestines. Additional growths in other areas of the body include:

• osteomas – outgrowths of bone that form on existing bones
• desmoid tumors – tumors that form in connective tissue
• fibromas – tumors that form in smooth muscle
• lipomas – lumps of fatty tissue under the skin
• epidermoid cysts – small, hard bumps beneath the skin
• epithelial cysts – fluid-filled growths under the skin
• adenomas – tumors in the adrenal and thyroid glands
• polyps in the stomach or small intestine
• extra teeth or other dental abnormalities
• congenital hypertrophy of retinal pigment epithelium (CHRPE) – a dark, flat spot on the eye’s retina

These noncancerous growths typically begin forming in puberty and may remain undetected for years.

How harmful are these growths?

Some are harmless and can be corrected cosmetically if needed. Others can cause serious consequences. Desmoid tumors, for example, can grow very aggressively inside the abdomen and press against internal organs. Even though they're noncancerous, desmoid tumors may become life-threatening.

Colon and rectal polyps pose the biggest health threat. They have an almost 100% chance of causing colorectal cancer by the time patients are in their 30s.

Gardner syndrome is similar to a condition named FAP – are they related?

Yes, Gardner syndrome is a subtype of familial adenomatous polyposis (FAP).

People with FAP develop multiple colon and rectal polyps. People with Gardner syndrome have these polyps, too. But they also develop other types of abnormal growths elsewhere in their bodies.

Gardner syndrome is named for geneticist Eldon J. Gardner, who discovered it in 1951 while studying a large family in Utah whose members were thought to have FAP. They had numerous colon and rectal polyps, but they also had multiple fibromas, osteomas and cysts throughout their bodies.

Does Gardner syndrome run in families?

Yes, people with Gardner syndrome have a 50% chance of passing it to their children.

How and when is Gardner syndrome diagnosed?

Genetic testing is the only way to definitively confirm a diagnosis of Gardner syndrome. The test checks for mutations in the APC gene.

Patients are referred for testing if they have a family history of the disease, or if a colonoscopy reveals more than 100 polyps in the colon and rectum. The average age of diagnosis is 25 when polyps typically begin causing side effects such as rectal bleeding, anemia and weight loss. These symptoms lead to a colonoscopy, which then leads to genetic testing.

The disease is occasionally diagnosed after a dentist notices extra teeth, or an eye doctor discovers a dark spot on the retina. This triggers a referral to a cancer specialist, who orders genetic testing.

How is Gardner syndrome treated?

Surgical removal of the colon and rectum is the only way to prevent the inevitable onset of colorectal cancer. Without this intervention, almost 100% of patients will develop the disease.

Starting as young as ages 10 to 12, people with a family history of Gardner syndrome start having annual colonoscopies to check for polyps, which begin forming during puberty.

When 30 to 50 polyps are detected, surgeons typically recommend removing the colon and rectum. Non-steroidal anti-inflammatory medications such as sulindac or celecoxib are prescribed to slow the growth of any remaining polyps.

Other tumors, bony growths or cysts in different areas of the body are noncancerous and usually don’t require treatment, although patients may want to remove them for cosmetic reasons.

After the colon and rectum are removed, patients are screened annually to check for:

• Noncancerous adrenal and thyroid gland tumors called adenomas that may become cancerous
• Invasive desmoid tumors that threaten internal organs
• Polyps in the upper digestive tract, including the esophagus, stomach and small intestine

Can Gardner syndrome be cured?

There’s no cure for Gardner syndrome. However, screenings, preventive surgeries and medications can significantly lessen the likelihood of a future cancer diagnosis. The earlier a patient is diagnosed and starts treatment, the better the results.

Request an appointment at MD Anderson online or by calling 1-877-632-6789.