KINESIOL 1Y03 Lecture Notes - Lecture 15: Enema, Sigmoidoscopy, National Cancer Institute
23 Jun 2018
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Screening + surveillance of CRC
Principles of screening
Screening = average risk population c.f. surveillance in high-risk groups e.g.: previous
neoplasia / IBD / FH
Aim of screening = to decrease incidence and early detection
Criteria for screening
Important health problem
Accepted treatment
Facilities for diagnosis and management
Latent/early symptomatic stage
Suitable / acceptable screening test
Natural history understood
Financially viable
Lead-time bias = artefactually increases the benefit of screening because, the early diseases
are detected (via screening), the longer ‘survival’ appears to be
Contenders for screening in CRC
Colonoscopy
= gold standard for examination of the colon
can be used for therapy
ideal on an individual basis
however: 1 day dietary restrictions (fluids only), severe bowel preparation, 1-2 days
off work, significant complication rate
hence for the population, there are problems with: manpower, time consumption,
quality, invasiveness, compliance and expense
BSG Audit 9223 – Gut 2004 showed completion rate of only 57% and many
deviations from best practise
colonoscopy is included in the AGA guidelines as an option for screening however is
realistically reserved for therapy and surveillance
Virtual colonoscopy
= spiral high resolution CT done in the prone or supine position
time and radiation dose required in decreasing
software 3D reconstruction occur
faecal tagging used to increase accuracy
sensitivity and specificity may be greater than colonoscopy
safe, no sedation, more tolerable for patients, extra-colonic information
however, most available data is obselete, high quality of equipment is required,
skilled interpretation is required, bowel prep still intensive, small polyps may be
covered (but faecal tagging will improve this)
Molecular testing (other stool tests)
= non-invasive
initial results are encouraging: 71% of cancer detected
however follow-up data is less impressive
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Screening = average risk population c. f. surveillance in high-risk groups e. g. : previous neoplasia / ibd / fh. Aim of screening = to decrease incidence and early detection. Lead-time bias = artefactually increases the benefit of screening because, the early diseases are detected (via screening), the longer survival" appears to be. Bsg audit 9223 gut 2004 showed completion rate of only 57% and many deviations from best practise colonoscopy is included in the aga guidelines as an option for screening however is realistically reserved for therapy and surveillance. = non-invasive initial results are encouraging: 71% of cancer detected however follow-up data is less impressive. May be able to identify high-risk individual for colonoscopy j of national cancer. Molecular markers: apc, k-ras, p% , bat-26, long dna, all of which are used in the. Pilot studies began from 2000; began in 2006 (instigated by health secretary john.
