Screening for colorectal cancer

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Screening for colorectal cancer

• Nigel Williams
• University Hospitals Coventry and Warwickshire

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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

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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

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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

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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)

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CRC screening- the data

Mandel JS Minnesota Hardcastle Nottingham Kronberg
Odense (Denmark) All were large scale RCTs in a
population setting
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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
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CRC screening- present guidelines

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CRC screening- present guidelines

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CRC screening- guidelines

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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
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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
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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
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CRC screening- how?

FOBT - to rehydrate or not - how often FOBT
FS Colonoscopy Virtual colonoscopy Immunological G
enetic testing of stool DNA
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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.
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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
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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
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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
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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
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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