Gardner syndrome

Gardner syndrome is caused by changes (mutations) in the APC gene, which is called a "tumor suppressor." Tumor suppressor genes encode proteins that are part of the system that controls cell growth and division. These proteins ensure that cells do not grow and divide too quickly or in an abnormal manner. Mutations in the APC gene lead to uncontrolled cell growth which results in the development of the polyps, tumors and cancers that can be associated with Gardner syndrome. The symptoms found in each person and the severity of the condition depend on which part of the APC gene is mutated.

Genetic testing is available for APC, the gene known to cause Gardner syndrome. Carrier testing for at-risk relatives and prenatal testing are possible if the disease-causing mutation in the family is known. Because colon screening for those at risk for Gardner syndrome begins as early as age ten years, genetic testing is generally offered to children by this age.

The Genetic Testing Registry (GTR) is a centralized online resource for information about genetic tests. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Gardner syndrome is diagnosed based on the following features:

• At least 100 colorectal polyps OR fewer than 100 polyps and a family member with Familial Adenomatous Polyposis or Gardner syndrome
• Osteomas (bony growths)
• Soft tissue tumors such as epidermoid cysts, fibromas, and desmoid tumors

These symptoms are usually identified using a combination of physical examination, colonoscopy, and X-rays of the long bones and/or jaw bone. The presence of other signs and symptoms such as stomach or small intestinal polyps; congenital hypertrophy of the retinal pigment epithelium (a flat, pigmented spot within the outer layer of the retina); and/or associated cancers, supports the diagnosis.

A diagnosis of Gardner syndrome can be confirmed by the identification of a disease-causing change (mutation) in the APC gene.

Gardner syndrome is inherited in an autosomal dominant manner. This means that to be affected, a person only needs a change (mutation) in one copy of the responsible gene in each cell. In some cases, an affected person inherits the mutation from an affected parent. Other cases may result from new (de novo) mutations in the gene. These cases occur in people with no history of the disorder in their family. A person with Gardner syndrome has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

The long-term outlook (prognosis) for people with Gardner syndrome depends on the signs and symptoms present in each person and the age of diagnosis. By age 35 years, 95% of affected people have polyps. Once they appear, the polyps rapidly increase in number. Without colectomy, hundreds to thousands of colon polyps are typically observed and colon cancer is inevitable. The average age of colon cancer diagnosis in untreated individuals is 39 years (range 34-43 years). However, with early diagnosis and high-risk management, the prognosis is good. In fact, the 5-year survival rate for patients who undergo protocolectomy is nearly 100%. If alternative surgeries are performed that remove the colon but not the rectum, the recurrence rate is 30% in 20 years and 45% in 30 years; continued surveillance of the remaining rectum is, therefore, imperative.

The skin abnormalities (epidermoid cysts, fibromas, and lipomas) associated with Gardner syndrome are mainly of cosmetic concern, as they do not appear to become malignant (cancerous). Osteomas (bony growths) do not usually cause medical problems and do not become malignant. Although desmoid tumors are typically benign (noncancerous), they have a tendency to invade surrounding tissues and/or compress nearby organs and can be very difficult to remove.

Although there is no cure for Gardner syndrome, treatment and management options are available to reduce the risk of cancer. For example, affected people typically undergo regular screening for the various polyps and tumors associated with Gardner syndrome to permit early diagnosis and treatment. This screening regimen may include:

• Sigmoidoscopy or colonoscopy every one to two years, beginning at age ten to 12 years. Once polyps are detected, colonoscopy is recommended annually until colectomy (removal of colon).
• EGD (esophagogastroduodenoscopy) beginning by age 25 and repeated every one to three years.
• Annual physical examination, including a thorough thyroid evaluation beginning in the late teenage years.
• Screening for desmoid tumors and hepatoblastoma (a specific type of liver cancer that is diagnosed in young children) may also be recommended in some people.

A colectomy is usually recommended when more than 20 or 30 polyps and/or multiple advanced polyps are identified. Sulindac, a nonsteroidal anti-inflammatory drug (NSAIDs), is sometimes prescribed in people with Gardner syndrome who have had a colectomy to treat polyps in the remaining rectum.

Treatment for desmoid tumors varies depending on the size and location of the tumor, but may include watchful waiting, surgery, NSAIDS, anti- estrogen medications, chemotherapy and/or radiation therapy. Osteomas (bony growths) may be removed for cosmetic reasons. Treatment of epidermoid cysts in Gardner syndrome is similar to that used for ordinary cysts and involves excision.

Cancer.Net, oncologist- approved cancer information from the American Society of Clinical Oncology, has information about Gardner syndrome. Click on the link to view the information.