Transcript Screening for Colorectal Cancer - Grand River Hospital

Screening for Colorectal
Cancer
Cancer Symposium: Measuring
the Benefits of Screening and
Treatment
October 2007
Why should we screen of
colon and rectal cancer?
Because it is common
• Third most common cancer in Canada
– 20,400 new cases
• Second most lethal
– 8,700 deaths
• The most lethal among non smokers
Natural History
• The polyp cancer sequence
• Surgical and endoscopic techniques
Because we can
Screening for CRC
• No symptoms
• Average risk
• High risk
Screening for CRC
• Average risk individual
– When to start?
• Age 50
– Incidence 1:500 age 40 -49 y
–
1:125
50-59 y
–
1:50
60-69 y
Fecal Occult Blood Testing
• The only screening test with Level I
evidence that it can decrease the
mortality from CRC
– NEJM 1993 Minnesota Trial
– Lancet 1996 European Study
• 18 yr follow-up from the Minnesota Trial
shows an 21% mortality reduction in the
screening cohort
FOBT
• “2 samples from each of 3 consecutive
stool samples, with dietary restrictions if
using a guaiac based test”
• Any positive result followed up with
colonoscopy
FOBT
• How often?
• High false positive rate
• Significant false negative rate
Canadian Task Force on
Preventative Health
• “the number needed to screen for 10
years to avert one death from colorectal
cancer is 1173”
Flexible Sigmoidoscopy: The
Good
• The scope is 50 cm long
– Easier
– Perforation rate is low
• Most cancers (in average risk
individuals) are within 50 cm
• Biopsy and polypectomy is possible
Flexible Sigmoidoscopy: The
Bad
• The scope is 50 cm long
• Perforation rate is 1.4 per 1000
• Prep is necessary
Flexible Sigmoidoscopy
• Good for 5 years
• ? Should one do a full colonoscopy if a
low risk polyp is found in the distal colon
– Lancet 2002 UK RCT found an 80%
mortality reduction form CRC
Double Contrast Barium
Enema
• No randomized trails that evaluate this
as a screening tool for average risk
individuals
• It does not see the rectum well
• It misses 50% of polyps < 1.0 cm
• Q 5 years
Combinations
• DCBE and Flex sig
– No data
• FOBT and Flex sig
– Limited data
Colonoscopy: The Good
• Although there is no evidence……
• Allows diagnostic biopsy and
endoscopic removal of polyps
• Shelf life of 10 years in average risk
individuals
Colonoscopy: The Bad
• Highly trained personnel
• Resource intense
• Expensive
• Do we have the capacity?
Colonoscopy: The Ugly
• Prep
• Perforation risk
– 1:1000 all comers
– 1:2000 screening
– 1:15000 mortality
Emerging Technologies
• Fecal DNA analysis
• Virtual colonoscopy
Virtual Colonoscopy
Emerging Technologies
• Fecal DNA analysis
• Virtual colonoscopy
• Micro array gene expression analysis
High Risk Individuals
• Good news and bad news
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Family History
FAP
HNPCC
IBD
Family history
• 1 first degree relative < 60 with CRC or
polyp disease or
• 2 first degree relatives with CRC at any
age
• Begin at age 40, or 10 years younger
than the youngest relative and continue
q 5 years
Family history
• 1 First degree relative > 60 with CRC or
polyp disease or
• 2 second degree relatives with CRC at
any age
• Should be screened as an average risk
but beginning at age 40
Family History
• 1 second degree relative or any number
of third degree relatives should be
screened as average risk
Familial Adenomatous
Polyposis (FAP)
• Flexible sigmoidoscopy at age 14
• +/- genetic testing
Hereditary Non-polyposis
Colon Cancer (HNPCC)
• Amsterdam II Criteria
– 3 relatives (at least I first degree)
– Successive generations
– One with Ca <50
– FAP r/o
HNPCC
• Colonoscopy q 2 years
• +/- genetic testing for MMR gene
mutation
• +/- genomic analysis of tissue for micro
satellite instability
Patients with Inflammatory
Bowel Disease
• Same for UC or Crohns
• 8 years after the onset of disease in pancolitis
• 15 years after onset in Left sided disease
• Colonoscopy q 1 - 2 years
Patients with a history of
Polyps
• Advanced adenoma
– >10 mm
– Villous architecture
– HGD
• >2 polyps less than 10 mm
• AGA……3 years
• CAG…….clinical judgment
Patients with a history of
polyps
• One or two polyps , each less than or =
10 mm
• 5 years
Summary
• Screening is good
• Begin at age 50 in average risk individuals
• Options
– FOBT +/- colonoscopy
– colonoscopy
• High risk individuals should have
colonoscopy
Questions