Treatment is key to preventing ca in FAP patients.
The disorder requires careful management, because untreated familial adenomatous polyposis (FAP) leads to colon cancer 100% of the time. Untreated patients develop colon cancer at an average age of 39 years, said Dr. Burt of the University of Utah in Salt Lake City.
He offered these tips for managing patients with FAP:
* Genetic testing is indicated in individuals and family members suspected of FAP. The disease should be suspected in any individual with more than 10-20 polyps. Available genetic tests have nearly 100% accuracy in detecting the autosomal dominant mutation that causes FAP.
* Genetic counseling is critical to help patients understand the illness and its consequences, and to deal with the psychological issues that may follow positive or negative tests. Patients need to understand the meaning of an indeterminate test, and they may need help dealing with economic and social issues. Some parents will want to have their young children tested, but Dr. Burt said that this testing should be discouraged until it becomes medically important, between the ages of 10 and 12 years.
* People with FAP develop hundreds or thousands of chronic adenomatous polyps, beginning at about age 16. Annual sigmoidoscopy should be performed starting between age 10 and 12 years for children who test positive for an FAP mutation. They should receive an upper endoscopy every 1-3 years, because patients with FAP often have gastric and duodenal adenomas that should be removed.
* Patients typically undergo a colectomy at the end of their high-school years. This greatly increases life expectancy.
* An attenuated form of FAP exists, in which patients typically develop only 10-30 polyps. The development of colon cancer is delayed about 10 years in these patients vs. patients who have the more common form of FAP, but their lifetime incidence is still 50%-80%. Colectomy is not always required for attenuated FAP.
* Congenital hypertrophy of the retinal pigment epithelium is a common comorbidity in patients with FAP, but Dr. Burt said this is never a clinical problem. Other common comorbidities are osteomas, epidermoid cysts, and fibromas, all generally of cosmetic interest only.
* Desmoid tumors may be more of a problem, especially in the abdomen. They are benign but can obstruct important structures such as the superior mesenteric artery, resulting in significant morbidity and even mortality. Desmoid tumors outside the abdomen are usually treated surgically. Treatment for those in the abdomen is delayed until they become symptomatic; chemotherapeutic approaches are typically used, but surgery and radiation may be necessary.
BY ROBERT FINN
San Francisco Bureau
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|Title Annotation:||Genetic Testing Indicated; familial adenomatous polyposis|
|Publication:||Internal Medicine News|
|Date:||Mar 15, 2004|
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