Introduction: Hereditary non-polyposis colorectal cancer (HNPCC) is a dominant inherited colorectal cancer syndrome, with lifetime risk up to 90% of developing colorectal cancer (CRC) for carriers of the genes. Screening with colonoscopy can reduce the CRC-rate by 62% and prevent CRC-deaths. The HNPCC-Register was established with the aim of identification and registration of Danish HNPCC-families and coordination of surveillance.
Materials and methods: The results of 703 colonic screenings in 396 asymptomatic individuals from 150 HNPCC-families were analysed and related to the family diagnosis.
Results: In 112 asymptomatic individuals, 31, colorectal cancers and 140 adenomas were diagnosed. Neoplasia was found in one fifth of the examinations and almost one third of the individuals developed an asymptomatic neoplasia which was detected by screening. At the time of the diagnosis, 77% of the colorectal cancers were localized (Dukes stage A or B).
Discussion: In Finland, screening for colorectal cancers in HNPCC-families prevents 25-45-fold more CRC-deaths compared to general population screening for colorectal cancer. The results of the Danish colonic HNPCC-screening reveal neoplasia in 21% of the examinations and the colorectal cancers found by screening were at a more favourable Dukes stage compared to sporadic CRC, and probably also CRC found by general population screening. The HNPCC-Register initiates surveillance together with the clinical genetic departments, but the results of the recommended colonic examinations are not automatically reported to the HNPCC-Register. To enable an in-depth investigation of the effect of CRC-screening in all Danish HNPCC-families, further financial resources should be allocated to the HNPCC-Register to collect the results.