What Is Gardner Syndrome?

Gardner syndrome is an inherited condition that is a type of familial adenomatous polyposis (FAP). FAP involves growths called polyps in the digestive tract, primarily in the colon and rectum. These growths start out benign and eventually become cancerous. 

In people with Gardner syndrome, the growths happen inside and outside the colon. Without intervention, people with Gardner syndrome have a very high risk of developing colon cancer.

Gardner syndrome was first described in 1951. The rare condition occurs in approximately two to four out of every million people worldwide.

Gardner Syndrome Symptoms

You may not know you have Gardner syndrome because the condition doesn’t always cause symptoms early on. A dentist may be the first healthcare professional to notice the signs of Gardner syndrome because the condition may cause dental abnormalities such as bony growths.

People with Gardner syndrome may also have skin abnormalities such as cysts, fibromas (benign tumors made of fibrous or connective tissue), and lipomas (benign fatty tumors).

Polyps typically start to form inside the colon at around the age of 16. Unless removed, the polyps eventually become cancerous, leading to early-onset colon cancer. People with this disease may also develop other cancers such as stomach cancer, thyroid cancer, or cancer of the adrenal gland.

Colon Cancer Symptoms

People with Gardner syndrome develop hundreds of polyps in their colon—sometimes thousands. These start benign but eventually become cancerous, which leads to colon cancer at a young age. Usually, this is seen in a person’s late 30s.

Colon cancer doesn’t always cause symptoms in its early stages. However, possible symptoms may include:

• Changes in the frequency of bowel movements
• Blood in the stool
• Diarrhea
• Constipation
• Feeling that the bowel isn’t emptying
• Abdominal discomfort or pain
• Weight loss without cause
  

Causes

Gardner syndrome is associated with mutations in the tumor-suppressing APC gene. When mutations happen in this gene, rapid cell growth and division can occur unchecked, leading to the growth of polyps, tumors, and cancer.

The condition is autosomal dominant, meaning you only need one copy of the mutated gene to have the disorder. This means that most people with Gardner syndrome have one parent with the condition.

Sometimes, Gardner syndrome can occur because of a new gene mutation. In cases like these, there’s no family history of the disease.

Diagnosis

If you know Gardner syndrome runs in your family, you may want to consider genetic testing for the APC gene.

A doctor will make a diagnosis of Gardner syndrome if a person has:

• At least 100 polyps in their colon, or fewer polyps and a family history of FAP or Gardner syndrome
• Bony growths
• Soft tissue cysts, fibromas, and desmoid tumors (a type of connective tissue tumor)
  

Doctors can detect these signs of Gardner syndrome using X-rays or colonoscopy. A doctor or dentist may notice bony growths during an X-ray, for example. However, the only way to confirm a Gardner syndrome diagnosis is to undergo genetic testing.

Treatment

There’s no cure for Gardner syndrome. However, it’s possible to manage the condition and reduce your risk of developing colon cancer or other associated cancers. 

It’s essential to get regular screenings to check for cancerous polyps and tumors. Your doctor may recommend the following screening options:

• Annual physical, including a thyroid evaluation 
• Screening for certain types of tumors that are more common in people with Gardner syndrome, including desmoid tumors
• Annual colonoscopy or sigmoidoscopy to check for polyps using a flexible tube with a camera inserted into the lower digestive tract
• Esophagogastroduodenoscopy (EGD) to examine the lining of the digestive tract using a flexible tube with a camera inserted through the mouth into the upper digestive tract
  

If a person knows they have Gardner syndrome early on in their life, screening may start at the age of 10 years old. Early screening is used to check for polyps and determine when it’s time to remove the colon.

Prevention-focused treatment may involve:

• Using nonsteroidal anti-inflammatory drugs (NSAIDs), such as sulindac
• Eating a healthy diet
• Taking a COX-2 inhibitor to slow polyp growth
  

Once doctors detect more than 20 to 30 polyps, they will typically recommend removal of the colon (colectomy). 

Doctors may also need to treat tumors other than colon polyps with chemotherapy or radiation. Most skin growths associated with Gardner syndrome are benign and don’t require treatment, although you may want to remove them for cosmetic reasons.

Prognosis

People with Gardner syndrome have a high risk of developing colon cancer and other cancers. However, if someone is diagnosed early, they may be able to lower their risk of developing complications.

The only way to stop colon cancer from developing in people with Gardner syndrome is to remove the colon. Some may opt to remove the large intestine and most of the rectum with a proctocolectomy procedure. Removing the rectum in addition to the colon decreases the chances of recurrence.

Summary

Gardner syndrome is an inherited condition that results in growths inside and outside the colon. While these start as benign polyps, people with Gardner syndrome have a very high risk of developing colon cancer at a young age.

Annual colon cancer screenings are one treatment tactic. But once there are numerous polyps, removal of the colon is recommended.

A Word From Verywell

Early detection is important for most cancers, but especially vital if you have Gardner syndrome. Removal of the colon is the only way to prevent early-onset colon cancer in people with Gardner syndrome. If you know you have a family history of this condition, regular screening is essential, starting with yearly colonoscopies at around age 10.

Frequently Asked Questions 

When is Gardner syndrome diagnosed?

People may know they have Gardner syndrome at a young age because they have a known family history of the disease. On average, diagnosis happens around the age of 25, which is when polyps start to cause symptoms.

How do you know if you have polyps?

Symptoms of colon polyps may include:

• Rectal bleeding 
• Anemia without an obvious cause
• Unexplained weight loss
  

In rare cases, people may have abdominal pain. However, most people with polyps have no symptoms at all.

How many patients with Gardner syndrome develop colon cancer?

Colon cancer is an inevitable complication of Gardner syndrome. The only way to prevent cancer from developing is to remove the colon and rectum. However, that doesn’t mean a person can’t develop other types of cancers common in people with FAP and Gardner syndrome.