Polyps---small fleshy growths---occur frequently in the colon and affect as many as 30 to 50 percent of adults. Ninety percent of polyps develop in patients older than 50, reports Anne Charette, RN, MSN of Tufts University on Up To Date. Polyps can become cancerous, although malignant processes normally take about 10 years, Charette states. Colon polypoid disease---disease associated with polyps in the large intestine---greatly increases the risk of developing colon cancer by causing polyps to grow at a younger age and, in some cases, in large numbers, a condition called polyposis.
Types
Of the several types of colon polypoid disease that exist, familial adenomatous polyposis, or FAP, and Lynch syndrome, also called hereditary nonpolyposis colorectal cancer, are the two most common. FAP has several variants: Gardner's syndrome causes the growth of fibrous tumors called desmoid tumors both inside and outside of the colon. Attenuated FAP, another form of the disease, affects people slightly later in life. A milder form, autosomal recessive FAP, causes less than 100 polyps to grow rather than the hundreds or thousands seen in other forms of FAP, the Genetics Home Reference states. Lynch syndrome causes polyp growth at a younger than normal age but does not cause polyposis. Turcot's syndrome, an extremely rare type of polypoid disease found in fewer than 100 people worldwide, causes polyposis and brain tumors, Net Doctor reports.
Causes
Most colon polypoid diseases are inherited diseases. Both Lynch syndrome---which causes 3 percent of all colon cancers, according to the Mayo Clinic---and FAP are autosomal dominant diseases, meaning that if one parent has the disease, the chance of each child inheriting it is 50 percent. In the milder form of FAP, autosomal recessive FAP, both parents must pass on the gene for a child to inherit the disease. Turcot's syndrome is caused by a gene mutation, Net Doctor reports.
Symptoms
Colon polyps normally cause few symptoms, although rectal bleeding and diarrhea may occur. Abdominal pain may occur in people with desmoid tumors, which affect 5 to 10 percent of people with FAP, Net Doctor reports. Desmoid tumors, although noncancerous, invade nearby tissue and are difficult to remove. People with desmoid tumors have a 20 percent chance of dying before age 35, Net Doctor adds.
Diagnosis
People with a known family history of colon polypoid disease need regular colonoscopies, examinations of the entire length of the colon with a lighted scope. Genetic testing for gene mutations that cause polypoid disease also helps make a diagnosis. People with classic FAP develop colon cancer, on average, by age 39, whereas people with attenuated FAP develop the disease later, around age 55, Genetics Home Reference reports.
Treatment
Removal of the entire colon, called a colectomy, eliminates the risk of developing colon polyps in people with colon polypoid disease, although cancers can still develop in other parts of the body.
Prognosis
Colon polypoid diseases require vigilant treatment starting at an early age. Average survival for FAP without treatment is 42, Net Doctor reports. Lynch disease causes polyp growth in the twenties and thirties, so early testing can help prevent the disease or allow for aggressive treatment early in its course.
