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Screening for colorectal cancer Nigel Williams University Hospitals Coventry and Warwickshire Philosophy of screening The early detection of cancer in a population setting makes the following assumptions: The Screening test is reliable and indicates the presence of cancer There are few false positive and false negatives The test is easy to apply and interpret Philosophy of screening The early detection of cancer in a population setting makes the following assumptions: The Screening test is inexpensive The test does not incur significant hazard to people screened That early diagnosis will significantly alter the natural history of the disease Philosophy of screening “Lead time bias” Although early treatment of a cancer may result in an apparently longer overall survival….there may be no overall change in the natural history of the disease CRC screening Colorectal cancer is ideally suited to screening: It is common (28-30 000 new cases/yr) There is a clearly identified premalignant lesion Treatment of the premalignant lesion reduces the risk of cancer Early detection of CRC improves overall survival The cost effectiveness of screening compares favourably with other screening strategies (eg breast, cervical) CRC screening- the data Mandel JS Minnesota Hardcastle Nottingham Kronberg Odense (Denmark) All were large scale RCTs in a population setting CRC screening- the data All three RCTs have demonstrated a reduction in the risk of dying from colorectal cancer. A meta-analysis of trials using Haemoccult reported a 16% reduction in colorectal cancer mortality CRC screening- present guidelines CRC screening- present guidelines CRC screening- guidelines CRC screening- what they say There is no longer any doubt that screening is an effective method of reducing colorectal cancer incidence and mortality rates Atkin WS, Northover JMA Gut 2002 CRC screening- what they say The persistent reduction in mortality from CRC in a biennial screening program with Haemoccult-II and a reduction in relative risk to less than 0.70….support attempts to introduce larger scale population screening programmes. Jorgensen OD et al Gut 2002 50 29-32 CRC screening- what they say There is no longer any doubt that screening is an effective method of reducing colorectal cancer incidence and mortality rates. The US Preventative Services Task Force recently reviewed the evidence and gave a grade A recommendation that all men and women should be screened for CRC Smith RA et al CA Cancer J Clin 2004 54 41-52 CRC screening- how? FOBT - to rehydrate or not - how often FOBT + FS Colonoscopy Virtual colonoscopy Immunological Genetic testing of stool DNA CRC screening- the reality The UK Colorectal Cancer Screening Pilot was established to determine the feasibility of screening for CRC in the UK population using FOBT and colonoscopy. The English site was based in Warwickshire and in Scotland, the population of Dundee were selected. CRC screening- the reality Funding was for all administration and setting up In Warwickshire 4 extra colonoscopy lists were required and were undertaken at consultant level. All participants had attended a ‘masterclass’ with C B Williams 4-5 colonoscopies per list CRC screening- the reality FOBT kits were posted to 187 777 people The response rate was approximately 60%. The FOB positivity rate was approximately 1.5% yielding 1700 colonoscopies over the 2 year period CRC screening- the reality A small number of people declined, were excluded for medical reasons or had their colonoscopy performed privately If the caecum was not intubated a DCBE was performed the same day CRC screening- the reality Of those patients undergoing colonoscopy, approximately 60% were normal, 30% had polyps and 10% had a cancer. Generally, Dukes A and B were overrepresented compared to a symptomatic population. It is too early for mortality and long-term survival data to be available CRC screening- the debate FOS or colonoscopy Manpower issues When to start screening What intervals How can we reduce the risk of polypectomy Genetic stratification of risk