Screening Mammography: Regret or no regret?

1. Screening Mammography:Regret or no regret? Joint Hospital Surgical Grand Round 19 May 2007 Yvonne Tsang Prince of Wales Hospital

2. Screening – WHO criteria • Routine examination of asymptomatic population for a disease • Criteria • Important health problem • Accepted treatment available • Facilities for diagnosis and treatment are available • Condition can be recognizable in latent/early stage • Suitable tests for screening available • The screening test is acceptable to population • Natural history of disease is well understood • Agreed policy on whom to treat is available • The cost of diagnosis and treatment should be economically balanced • Case finding should be continued Wilson JHG. The Principle and Practice of Screening for disease. Public Health Paper. Geneva 1968

3. Breast cancer • Suitable for screening • Pre-malignant stage • Early detection would affect management • Acceptance is high in Western countries • Screening mammography is widely recommended in Western countries for women age 50 years or older

4. Breast cancer • Highest incidence among all female cancers in Hong Kong since 1994 • Incidence is rising • 22% of all cancers in women in 2004 • Cumulative life-time risk is 1 in 22 • Hospital Authority Hong Kong Cancer Registry

5. Incidence and mortality Hong Kong Cancer Registry 2004

6. Hong Kong Cancer Registry

7. Mammogram • Two views of each breast • CC and MLO views

8. Suspicious lesions • Mass • clustered microcalcifications • architectural distortion • asymmetry

9. Performance Joshua J. Fenton et al.NEJM Apr 2007

10. Screening mammography - RCTs

11. The health Insurance Plan (HIP) of Greater New York trial • The first RCT for screening mammography • > 60,000 women recruited • Clinically significant reduction of mortality for 30% in study group by 10 years

12. Results from RCTs • Reduction in mortality was consistently demonstrated for women age 50 years and older • Mortality reduction ~ 17 to 31% • Swedish Two-Country Trial in 1977 • Edinburgh Trial 1979-1981 • Canadian National Breast Screening Study 1980-1985

13. Screening mammography - Meta-analysis • Reduces breast cancer mortality in women aged 50–74 after 7–9 years follow up • Regardless of screening interval and no. of views per screen Kerliokowske K. et al. JAMA 1995 Jan11;273(2):149-54

14. Criticisms on previous RCTs • Baseline imbalance in 6 of 8 RCTs identified trials • Inconsistencies in no. of women randomized in 4 RCTs • No effect of screening on improving breast cancer mortality in the 2 adequately randomized trials Peter C Gotzsche, Ole Olsen. The Lancet. Jan 8,2000

15. Against screening mammography • False positive • 23% women screened had at least one false positive mammogram over 10 years • 49.1% cumulative risk of a false positive results after 10 mammograms • Unnecessary scanning, biopsies • Anxiety, fear, worry

16. False positive • For every $100 spent for screening, an additional $33 was spent to evaluate false positive results • Ten-year risk of false positive screening mammograms and clinical breast examinations. NEJM Apr1998 338:1089-96

17. Digital vs Film mammography • Accuracy of digital mammography is higher especially in • Women under age of 50 • Dense breasts • Premenopausal or perimenopausal women • Etta D. Pisano et al. NEJM Oct2005

18. NHS Breast cancer screening programme • Since 1998 • 1.3 million women being screened each year • About 1 in 8 women screened regularly by the NHSBCP will be recalled for assessment at least once over 10 years • Cancers in screened women are smaller and less likely need mastectomy

19. NHS Breast cancer screening programme • One fewer women will die from breast cancer for every 400 women screened regularly by the NHSBCP over 10-year period • Currently NHSBCP saves ~1400 lives each year in UK • Spends about £3000 for every year of life saved • NHSBSP Publication no 61 Feb 2006

20. Situation in Hong Kong • No population screening for breast cancer • Lower incidence compared with Western countries • The value of mammography screening may be lower than Western countries • No RCT

21. Estimated age-specific rates of breast cancer incidence for women age 50 to 69 years Muir C et al eds (1987) Cancer Incidence in Five Continents International Agency for Research on Cancer and the International Association of Cancer Registries, World Health Organisation, Lyon.

22. Situation in Hong Kong • Number needed to screen in HK is 1302 women for 10 years compared with 666 in US in year 1996 • Accuracy of mammogram is lower in Chinese • Average Chinese breast has a smaller volume (224.5 cm3 vs 585.1 cm3 in British women) • Denser with less fat content

23. Local data from KWH • Opportunistic screening • 5 – year period • 31378 asymptomatic women • 46637 mammograms performed • 2 views, double reading • Crude cancer detection rate 5 per 1000 • Lui CY et al. Hong Kong Med J Apr 2007

24. Future • Increasing breast cancer awareness • Opportunistic screening services

25. Conclusions • Increasing breast cancer incidence in HK • Heightened public health awareness • Ever-increasing demand for quality breast screening • Not only detect cancer • Detecting early cancers leading to better prognosis • Feasibility of treatment with less morbidity • Population screening?

26. The End Thank you!