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The New Screening Intervals

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The New Screening Intervals. Dr Tony Maddox Dept of Cytology West Herts NHS Trust. Principles of Screening (1). Disease Common health problem High morbidity and mortality Well-understood natural history Long pre-clinical phase. Principles of Screening (2). Population

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The New Screening Intervals

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  1. The New Screening Intervals Dr Tony Maddox Dept of Cytology West Herts NHS Trust

  2. Principles of Screening (1) • Disease • Common health problem • High morbidity and mortality • Well-understood natural history • Long pre-clinical phase

  3. Principles of Screening (2) • Population • Well-defined and identifiable as at risk • Test • Should detect pre-clinical disease • Accurate, acceptable, inexpensive • Treatment • Effective, acceptable, minimal side-effects

  4. Purpose of Cervical Screening • To reduce the incidence of carcinoma of the cervix • by detecting and treating CIN • ultimately leading to decreased mortality from cervical carcinoma

  5. Pre-2003 Intervals • Women 20 – 64 • Intervals 3 – 5 years • Introduced in 1988 with call/recall

  6. July 7th 2003 • Benefit of cervical screening at different ages:evidence from the UK audit of screening histories • Br J Cancer (2003) 89, 88 – 93 • P Sasieni, J Adams, J Cusick

  7. Recommendations • Under 25 Do not screen • 25 – 49 3 – yearly screening • 50 – 64 5 – yearly screening • 65+ only screen those not screened since age 50

  8. October 22nd 2003 • NHSCSP accept recommendations and announce new screening intervals on same day as introduction of LBC • What’s the evidence?

  9. Audit of Screening Histories • 1988 – database of women with cervical cancer reported by self-selected HAs • Now over 2500 cases • This paper – 1305 women with IB+ • 2532 matched controls

  10. 1305 women: age at diagnosis • 20-24 13 0.8% (1.3%) • 25-39 425 24.6% (28.7%) • 40-54 481 27.9% (26.9%) • 55-69 386 22.4% (19.8%)

  11. 55-69 age range

  12. 40-54 age range

  13. 20-39 age range

  14. Recommendations • Taking these age groups and subtracting five years, it would seem: • 50-65 five yearly • 35-49 three yearly • 34 or less three yearly or more often • However, a balance must be struck between benefit and harm, taking into account absolute risk and effectiveness

  15. Effect of screening by age

  16. Effect of Screening by Age • The younger the age group, the more similar is the proportion of women in the group with cancer and the group without cancer who have been screened • Screening appears not to be effective at younger ages

  17. 20-24:how common is cancer? Source:Cancer Research UK, CancerStats, Cervical Cancer-UK, Jan 2003

  18. 20-24:how common is cancer? • ie about 40 cases in the UK in 1998 • Rate of 2.5/100,000 women • about 25 cases in England/Wales • 4 deaths in England/Wales in1998

  19. The international view Source:IARC Data 2000

  20. The international view 1995 Source: http://www.who.int/whosis/

  21. The international view 1998 Source:http://www.who.int/whosis/

  22. International data Suggests that whether or not, when or how often screening takes place has no effect on incidence or mortality in 20-24 age group

  23. Is screening harmful? • Stats Bulletin - England 2002-3 • 350,000 smears in 20-24 • 21,000 mild, 23,000 borderline • ~10,000 sent to colp with low grade • ~10,000 mod + severe • ~10,000 sent to colp with high grade

  24. Is screening harmful? • Low grades • 10% have LLETZ on first attendance • 55% have diagnostic biopsy • assume half of these have LLETZ later • 3700 LLETZs in total • assume 75% regression • ~2800 unnecessary LLETZs

  25. Is screening harmful? • High grades • 45% have LLETZ on first attendance • 35% have diagnostic biopsy • assume half of these have LLETZ later • 6200 LLETZs in total • assume 10% regression • 620 unnecessary LLETZs

  26. Is screening harmful? • ie about 3500 LLETZs/year for disease which will regress if left alone • other problems • anxiety • colp clinics overloaded • about 1/6 of referrals to colp in 2002-3 were from this age group

  27. LLETZ problems • Premature delivery • Crane et al Nov 2003 • Risk doubled by previous LLETZ • Cervical stenosis • Occasional acute complications

  28. Coverage • Coverage declining in 20-24 • 52% in 2002-3

  29. Screening in 20-24 - Summary • Cervical cancer is a rare disease • Appears to be ineffective • UK data • International data • Results in substantial overtreatment • Coverage is falling anyway

  30. Screening intervals - Summary • Under 25 Do not screen • 25 – 49 3 – yearly screening • 50 – 64 5 – yearly screening • 65+ only screen those not screened since age 50

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