Identification of Patients at Risk for Hereditary Colorectal Cancer

Abstract

Diagnosis of hereditary colorectal cancer syndromes requires clinical suspicion and knowledge of such syndromes. Lynch syndrome is the most common cause of hereditary colorectal cancer. Other less common causes include familial adenomatous polyposis (FAP), Peutz-Jeghers syndrome (PJS), juvenile polyposis syndrome, and others. There have been a growing number of clinical and molecular tools used to screen and test at risk individuals. Screening tools include diagnostic clinical criteria, family history, genetic prediction models, and tumor testing. Patients who are high risk based on screening should be referred for genetic testing.

Genetic risks and familial associations of small bowel carcinoma

“…Polyps could be sessile or pedunculated and histology's may vary from tubular to villous adenoma. Most patients develop polyps by second decade and if untreated colon malignancy by the fourth decade (15% of gene carriers by age 10 years, 75% by 20 years, and 90% by 30 years) [3] . The incidence of small intestinal cancers in FAP is not clear however the adenoma-carcinoma sequence for development of cancer is well established [3][4][5][6] .…”

“…Most patients develop polyps by second decade and if untreated colon malignancy by the fourth decade (15% of gene carriers by age 10 years, 75% by 20 years, and 90% by 30 years) [3] . The incidence of small intestinal cancers in FAP is not clear however the adenoma-carcinoma sequence for development of cancer is well established [3][4][5][6] . In addition these patients are predisposed to multiple small bowel adenomatous polyps usually in the duodenum and periampullary region [7,8] .…”

“…LS accounts for 3% to 5% of all CRC [25] and it is the commonest inherited colon cancer syndrome. The average age of malignancy in LS is 44 years, vs 64 years in sporadic CRC [3,17] . The risk factors for SBA in LS patient's increase with age, beginning at 40 years and a tenfold rise by the age of 60 [26] .…”

High Rate of Advanced Colorectal Polyps in a 10-Year-Long Retrospective Study in Qazvin, Iran

“…Since most studies into colon polyps did not consider these diseases, we did not find similar studies for comparison. FAP and other genetically-induced polyposis syndromes only constitute about 1% of colon cancer, but their early diagnosis is very important, because they are preventable (Mishra and Hall, 2012). Furthermore, because young people make up a significant percentage of patients with colon cancer in Iran (Pourhoseingholi and Zali, 2012;Hajmanoochehri et al, 2014), and these young people probably have a worse survival rate (Elsamany et al, 2014), it is important to study diseases related to colon cancer.…”

“…Patients with a neoplastic polyp were checked for the presence of histological and historical evidence of the familial polyposis syndrome (FAP) and IBD. A positive family history and/or multiplicity and neoplasticity of polyps were used as criteria for confirming the FAP (Mishra and Hall, 2012).…”