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 y – 1: y – 1: 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 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 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