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

Screening – WHO criteria Routine examination of asymptomatic population for a disease Criteria 1.Important health problem 2.Accepted treatment available 3.Facilities for diagnosis and treatment are available 4.Condition can be recognizable in latent/early stage 5.Suitable tests for screening available 6.The screening test is acceptable to population 7.Natural history of disease is well understood 8.Agreed policy on whom to treat is available 9.The cost of diagnosis and treatment should be economically balanced 10.Case finding should be continued Wilson JHG. The Principle and Practice of Screening for disease. Public Health Paper. Geneva 1968

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

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

Incidence and mortality Hong Kong Cancer Registry 2004 New CaseDeath Number of cases registered2, Rank13 Relative Frequency (%)229.9 Median age (years)5260 Crude Rate Cumulative life-time risk (0-74 yrs)1 in 221 in 106 Mortality : Incidence Ratio 0.20

Hong Kong Cancer Registry

Mammogram Two views of each breast –CC and MLO views

Suspicious lesions Mass clustered microcalcifications architectural distortion asymmetry

Performance Joshua J. Fenton et al. NEJM Apr 2007 SpecificitySensitivityPPV All mammograms Age at mammography >=

Screening mammography - RCTs Study Start day Screening interval (months) No. of views No. randomized Screening control New York ,13130,565 Malmo ,08821,195 Kopparberg ,58918,582 Ostergotland ,49137,403 Edinburgh then 122,92621,342 Canadian ,92544,910 Stockholm – 28140,31819,943 Gotenburg ,72414,217 All studies248,192208,157

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

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 –Canadian National Breast Screening Study

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

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

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

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 Apr :

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

NHS Breast cancer screening programme Since 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

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

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

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.

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 cm 3 vs cm 3 in British women) –Denser with less fat content

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

Future Increasing breast cancer awareness Opportunistic screening services

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?

The End Thank you!