screening mammography: regret or no regret?

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

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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 Important health problem Accepted treatment available - PowerPoint PPT Presentation

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Page 1: Screening Mammography: Regret or no regret?

Screening Mammography:

Regret or no regret?

Joint Hospital Surgical Grand Round

19 May 2007Yvonne Tsang

Prince of Wales Hospital

Page 2: Screening Mammography: Regret or no regret?

Screening – WHO criteria• Routine examination of asymptomatic

population for a disease• Criteria

1. Important health problem2. Accepted treatment available3. Facilities for diagnosis and treatment are available4. Condition can be recognizable in latent/early stage5. Suitable tests for screening available6. The screening test is acceptable to population7. Natural history of disease is well understood8. Agreed policy on whom to treat is available9. The cost of diagnosis and treatment should be

economically balanced10.Case finding should be continued

Wilson JHG. The Principle and Practice of Screening for disease. Public Health Paper. Geneva 1968

Page 3: Screening Mammography: Regret or no regret?

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

Page 4: Screening Mammography: Regret or no regret?

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

Page 5: Screening Mammography: Regret or no regret?

Incidence and mortality Hong Kong Cancer Registry 2004

New Case DeathNumber of cases registered

2,273 454

Rank 1 3Relative Frequency (%) 22 9.9Median age (years) 52 60Crude Rate 63.7 12.7Cumulative life-time risk (0-74 yrs)

1 in 22 1 in 106

Mortality : Incidence Ratio 0.20

Page 6: Screening Mammography: Regret or no regret?

Hong Kong Cancer Registry

Page 7: Screening Mammography: Regret or no regret?

Mammogram• Two views of each breast

– CC and MLO views

Page 8: Screening Mammography: Regret or no regret?

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

Page 9: Screening Mammography: Regret or no regret?

Performance

Joshua J. Fenton et al. NEJM Apr 2007

Specificity

Sensitivity

PPV

All mammograms 89.2 83.1 4.1Age at

mammography40-44 87.2 72.2 1.345-49 87.6 80.3 2.250-54 88.6 82.3 3.155-59 89.4 83.9 4.560-64 90.0 84.6 5.365-69 90.6 86.6 6.570-74 91.6 84.6 7.9>= 75 92.0 84.5 8.9

Page 10: Screening Mammography: Regret or no regret?

Screening mammography - RCTsStudy

Start

day

Screening

interval (months

)

No. of

views

No. randomized

Screening control

New York 1963 12 2 30,131 30,565Malmo 1976 21 2 21,088 21,195Kopparberg

1977 24 1 38,589 18,582

Ostergotland 1977 24 1 38,491 37,403

Edinburgh 1979 24 2 then 1

22,926 21,342

Canadian 1980 12 2 44,925 44,910Stockholm 1981 24 – 28 1 40,318 19,943Gotenburg 1982 18 2 11,724 14,217All studies 248,19

2208,157

Page 11: Screening Mammography: Regret or no regret?

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

Page 12: Screening Mammography: Regret or no regret?

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

Page 13: Screening Mammography: Regret or no regret?

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

Page 14: Screening Mammography: Regret or no regret?

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

Page 15: Screening Mammography: Regret or no regret?

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

Page 16: Screening Mammography: Regret or no regret?

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

Page 17: Screening Mammography: Regret or no regret?

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

Page 18: Screening Mammography: Regret or no regret?

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

Page 19: Screening Mammography: Regret or no regret?

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

Page 20: Screening Mammography: Regret or no regret?

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

Page 21: Screening Mammography: Regret or no regret?

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 ContinentsInternational Agency for Research on Cancer and the International Association of Cancer R

egistries, World Health Organisation, Lyon.

Page 22: Screening Mammography: Regret or no regret?

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

Page 23: Screening Mammography: Regret or no regret?

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

Page 24: Screening Mammography: Regret or no regret?

Future• Increasing breast

cancer awareness• Opportunistic

screening services

Page 25: Screening Mammography: Regret or no regret?

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?

Page 26: Screening Mammography: Regret or no regret?

The End

Thank you!