Bowel Screening in Scotland – Current Challenges and Possible Solutions

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

2. 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

4. 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)

5. National UK Colorectal Cancer Screening Pilot Aim: to test the feasibility of introducing gFOBT screeing into the NHS

7. Organisation of the bowel cancer screening programme - Scotland Single Centre Investigation and treatment devolved to health boards (n=14) Age range 50 - 74

9. Rate ratio of Colorectal Cancer invited vs controls Overall 0.90 (0.830 – 0.989) Relative reduction in CRC mortality 10% Participants only 0.73 (0.653 – 0.824) Relative reduction in CRC mortality 27%

10. Positive Predictive Value of Screening Colonoscopy Carcinoma 14.6% Adenoma 35.9% No Neoplasia 49.5%

11. Uptake- Gender and Deprivation % SIMD

12. Cancers Diagnosed in the Screened Population

13. Gender distribution - all rounds %

14. Site distribution - all rounds %

15. Issues to address • Interval Cancers • Gender inequality • Rectal and right-sided cancers • Uptake

16. “Blood in stool” tests Flexible Sigmoidoscopy Colonoscopy

17. Colonoscopy • No RCT results • Case control studies only • But – highly sensitive and 100% specific

18. If an insensitive test with imperfect specificity reduces mortality…..

19. £ £££££

20. 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

21. ICRF/MRC Study Total no: 354262 Interested : 194726 (55%) Randomised: 170432 Invited for screening: 57254 Control: 113178 Attended: 40674 (71%)

22. Mortalityfrom CRC

23. Incidence of CRC

24. Incidence of L-sided CRC

25. Incidence of R-sided CRC

26. Potential Advantages of FS • Disease prevention • Enhanced detection of left-sided adenomas • Detection of rectal cancer • Unlikely to be a gender difference

27. Potential Problems with FS • Uptake • Unlikely to be >30% • Possibility of exaggerated deprivation gradient • Effect on right-sided cancers

28. Alternative Strategy Increasing sensitivity of FOBT?

29. 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

30. Quanitative FIT and Disease

31. “FIT 400” n=17783 n=20358

32. “FIT 50” n=17783 n=20358

33. Specificity Sensitivity

34. FIT 50 • 10% positivity rate • 90% sensitive for cancer • 40% sensitive for adenoma • Lower detection limit may be more sensitive But…

35. Question ? • Sigmoidoscopy for all • FIT 50 and colonoscopy for ~ 10% or

36. 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