Characteristics of colorectal cancers detected in European patients positive for a blood test based on the Septin9 DNA methylation biomarker.

Abstract

e21163 Background: Colorectal cancers are the second leading cause of death by cancer. In Switzerland, about 1,600 people die of colorectal cancer and 4,000 new cases are diagnosed each year, the highest incidence in Europe. Disease risk increases rapidly after 50 years of age. The five year survival rate for colorectal cancer diagnosed an early stage of disease is greater than 90 percent, meaning that early detection is key in preventing colorectal cancer-related mortality. Every adult over 50 years is advised to participate in regular colorectal cancer screening. Standard colorectal cancer screening tools include fecal occult blood tests (FOBT) and colonoscopy, the gold standard. A new molecular diagnostic blood test for colorectal cancer based on Septin9 has been available as a CE-marked kit for over a year in Europe. Methods: It is based on the observation that even early stage colorectal cancer releases methylated SEPT9 DNA into the bloodstream that can be sampled for detection of methylated SEPT9 by a simple polymerase chain reaction based assay. The physician can prescribe the test for asymptomatic patients easily as no dietary restrictions are necessary and only a 10 ml blood sample is required. If the test is negative, the patient is recommended for repeat screening after one to two years. Results: We will describe the characteristics of colorectal cancers that have been identified in patients positive for the Septin9 test in routine clinical use. As of October 2010, compliance to follow-up colonoscopy in Septin9 positive subjects we followed was greater than 90%. Invasive adenocarcinoma was diagnosed in two Septin9 positive patients. Adenomatous polyps with mid to high grade dysplasia were identified in an additional seven patients. Conclusions: In summary, the Septin9 test offers patients with certain physical conditions, e.g. acute hemorrhoids, a reasonable alternative for colorectal cancer screening.