Evaluation of endoscopic characteristics of upper gastrointestinal polyps in patients with familial adenomatous polyposis

Worldwide Impact of Upper Gastrointestinal Disease in Familial Adenomatous Polyposis

Familial adenomatous polyposis (FAP) is the most common hereditary colorectal adenomatous polyposis and cancer syndrome which has historically been associated with a near absolute risk of colorectal cancer. However, the morbidity and mortality from colorectal cancer has been greatly diminished by pre-symptomatic genetic testing which identifies affected individuals and by appropriately timed, risk-reducing surgery of the colorectum. Following colorectal surgery, cancer risk beyond the retained rectum or ileal pouch includes other gastrointestinal organs, especially those of the upper gastrointestinal tract. While genotype-phenotype correlations exist for the severity of colonic polyposis, they have not been demonstrated for upper gastrointestinal tract manifestations. We reviewed the impact of ethnicity on the upper gastrointestinal manifestations of FAP by a comparison of published data in patients with FAP from Asian and Western countries. Our main findings demonstrate that following risk-reducing surgery to mitigate colorectal cancer risk, patients with FAP remain at increased risk for upper gastrointestinal polyposis and cancer. The duodenal and gastric phenotype differs between patients with FAP from the West and the East, and all should be followed in a multidisciplinary surveillance program. Following risk-reducing surgery to mitigate colorectal cancer risk, patients with familial adenomatous polyposis remain at increased risk for upper gastrointestinal polyposis and cancer. The duodenal and gastric phenotype differs between patients with FAP from the West and the East, and all should be followed in a multidisciplinary surveillance program.

Genetic predisposition to gastric cancer

Gastric cancer ranks as the third leading cause of cancer mortality worldwide and confers a 5-year survival of 20%. While most gastric cancers are sporadic, ~1%-3% can be attributed to inherited cancer predisposition syndromes. Germline E-cadherin/CDH1 mutations have been identified in families with an autosomal dominant inherited predisposition to diffuse gastric cancer. The cumulative risk of gastric cancer for CDH1 mutation carriers by age 80 years is reportedly 70% for men and 56% for women. Female mutation carriers also have an estimated 42% risk for developing lobular breast cancer by age 80 years. However, most individuals meeting clinical criteria for hereditary diffuse gastric cancer syndrome (HDGC) do not have a germline CDH1 mutation, and germline CDH1 mutation carriers do not all exhibit similar clinical outcomes in terms of age of diagnosis or cancer types. E-cadherin (CDH1) as the one known causative gene for HDGC accounts for only 40% of cases, leaving 60% with an unknown genetic diagnosis. In addition to HDGC, we will review other genetic syndromes with elevated gastric cancer risk, as well as newly implicated alterations in other genes (CTNNA1, DOT1L, FBXO24, PRSS1, MAP3K6, MSR1, and INSR) that may affect gastric cancer susceptibility and age-specific penetrance.