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Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells...

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Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee
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Page 1: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Bowel Screening in Scotland – Current

Challenges and Possible Solutions

Prof. Bob Steele

Ninewells Hospital, University of Dundee

Page 2: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Proving Screening Works

Population-based randomised trials in which the whole group offered screening (including refusers and interval cancers) is compared with the control group

Page 3: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.
Page 4: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Disease-Specific Mortality in gFOBT Randomised Trials

(Relative Risks)

• Minnesota– Annual 0.67 (CI 0.51-0.83)– Biennial 0.79 (CI 0.62 - 0.97)

• Nottingham– Biennial 0.85 (CI 0.74 - 0.98)

• Funen– Biennial 0.82 (CI 0.68 - 0.99)

• Göteborg– Biennial 0.84 (CI 0.71-0.99)

Page 5: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

National UK Colorectal Cancer Screening Pilot

Aim: to test the feasibility of introducing gFOBT screeing into the NHS

Page 6: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.
Page 7: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Single Centre

Investigation and treatment devolvedto health boards (n=14)

Age range 50 - 74

Organisation of the bowel cancer screening programme - Scotland

Page 8: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

0

1

2

3

4

5

CR

C m

orta

lity/

10

00 p

ers

ons

0 1 2 3 4 5 6 7 8 9 10Years since screening/matched date

Invited for screening Controls

Rate and 95% CI (Nelson-Aalen estimates)Cumulative Mortality from Colorectal Cancer

Page 9: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Rate ratio of Colorectal Cancer invited vs controls

Overall0.90 (0.830 – 0.989)

Relative reduction in CRC mortality 10%

Participants only 0.73 (0.653 – 0.824)

Relative reduction in CRC mortality 27%

Page 10: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Positive Predictive Value of Screening Colonoscopy

CarcinomaCarcinoma

14.6%14.6%

AdenomaAdenoma

35.9%35.9%No NeoplasiaNo Neoplasia

49.5%49.5%

Page 11: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Uptake- Gender and Deprivation

%

SIMD

Page 12: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Round 1 Round 2 Round 3

Screen -detected 351 (56.6%)

208 (46.5%)

139 (35.7%)

True interval 193 (31.2%)

213 (47.7%)

229 (58.9%)

Missed 2 (0.3%)

4 (0.9%)

2 (0.5%)

Miscellaneous 66 (10.7%)

22 (4.9%)

19(4.9%)

Not on Socrates 6(1%)

0 0

Cancers Diagnosed in the Screened Population

Page 13: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Gender distribution - all rounds

%

Page 14: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Site distribution - all rounds

%

Page 15: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Issues to address

• Interval Cancers

• Gender inequality

• Rectal and right-sided cancers

• Uptake

Page 16: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

“Blood in stool” tests

Flexible Sigmoidoscopy

Colonoscopy

Page 17: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Colonoscopy

• No RCT results

• Case control studies only

• But – highly sensitive and 100% specific

Page 18: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

If an insensitive test with imperfect specificity reduces

mortality…..

Page 19: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Test Accuracy Acceptability Risk

FOBT + +++ -

Flex-sig ++ ++ +

Colonosc +++ + +++£££££

£

Page 20: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

ICRF/MRC Study(Oct 1996 – March 1999)

• Single flexible sigmoidoscopy with removal of adenomas– 55-64 years

• High risk colonoscopy– adenoma > 1cm– 3+ adenomas– tubulovillous or villous histology– 20+ hyperplastic polyps above distal rectum– cancer

Page 21: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

ICRF/MRC Study

Total no: 354262

Interested : 194726 (55%)

Randomised: 170432

Control: 113178Invited for screening: 57254

Attended: 40674 (71%)

Page 22: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Mortality from CRC

Page 23: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Incidence of CRC

Page 24: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Incidence of L-sided CRC

Page 25: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Incidence of R-sided CRC

Page 26: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Potential Advantages of FS

• Disease prevention– Enhanced detection of left-sided

adenomas

• Detection of rectal cancer

• Unlikely to be a gender difference

Page 27: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Potential Problems with FS

• Uptake– Unlikely to be >30%– Possibility of exaggerated deprivation

gradient

• Effect on right-sided cancers

Page 28: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Alternative Strategy

Increasing sensitivity of FOBT?

Page 29: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

gFOBT vs FIT

• gFOBT– Based on Guaiac reaction– Not specific for haemoglobin– Messy to do

• FIT– Immunological– Specific for human haemoglobin– Easy to do– QUANTITATIVE

Page 30: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Normal DD HP LRA HRA Cancer0

100

200

300

400

500

600

700

800

Fae

cal

hae

mo

glo

bin

(n

g/m

l)Quanitative FIT and Disease

Page 31: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

n=20358 n=17783

“FIT 400”

Page 32: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

n=20358 n=17783

“FIT 50”

Page 33: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Sensitivity Specificity

Page 34: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

FIT 50

• 10% positivity rate

• 90% sensitive for cancer• 40% sensitive for adenoma• Lower detection limit may be more sensitive

But…

Page 35: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Question

• Sigmoidoscopy for all

• FIT 50 and colonoscopy for ~ 10%

or ?

Page 36: Bowel Screening in Scotland – Current Challenges and Possible Solutions Prof. Bob Steele Ninewells Hospital, University of Dundee.

Potential Pros

• Sigmoidoscopy– Detection of left-sided adenomas and protection from left sided cancer

– Detection of rectal cancer

• FIT 50– Uptake

– Detection of right-sided cancer


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