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The New Screening Intervals

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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