Screening Mammography:Regret or no regret?Joint Hospital Surgical Grand Round19 May 2007Yvonne TsangPrince of Wales Hospital

Screening WHO criteriaRoutine examination of asymptomatic population for a diseaseCriteriaImportant health problemAccepted treatment availableFacilities for diagnosis and treatment are availableCondition can be recognizable in latent/early stageSuitable tests for screening availableThe screening test is acceptable to populationNatural history of disease is well understoodAgreed policy on whom to treat is availableThe cost of diagnosis and treatment should be economically balancedCase finding should be continuedWilson JHG. The Principle and Practice of Screening for disease. Public Health Paper. Geneva 1968

Breast cancerSuitable for screeningPre-malignant stageEarly detection would affect managementAcceptance is high in Western countriesScreening mammography is widely recommended in Western countries for women age 50 years or older

Breast cancerHighest incidence among all female cancers in Hong Kong since 1994Incidence is rising22% of all cancers in women in 2004Cumulative life-time risk is 1 in 22

Hospital Authority Hong Kong Cancer Registry

Incidence and mortality Hong Kong Cancer Registry 2004

Hong Kong Cancer Registry

MammogramTwo views of each breastCC and MLO views

Suspicious lesionsMassclustered microcalcificationsarchitectural distortionasymmetry

PerformanceJoshua J. Fenton et al. NEJM Apr 2007

Screening mammography - RCTs

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

Results from RCTsReduction in mortality was consistently demonstrated for women age 50 years and olderMortality reduction ~ 17 to 31%Swedish Two-Country Trial in 1977Edinburgh Trial 1979-1981Canadian National Breast Screening Study 1980-1985

Screening mammography - Meta-analysisReduces breast cancer mortality in women aged 5074 after 79 years follow upRegardless of screening interval and no. of views per screen

Kerliokowske K. et al. JAMA 1995 Jan11;273(2):149-54

Criticisms on previous RCTsBaseline imbalance in 6 of 8 RCTs identified trialsInconsistencies in no. of women randomized in 4 RCTsNo effect of screening on improving breast cancer mortality in the 2 adequately randomized trialsPeter C Gotzsche, Ole Olsen. The Lancet. Jan 8,2000

Against screening mammographyFalse positive23% women screened had at least one false positive mammogram over 10 years49.1% cumulative risk of a false positive results after 10 mammogramsUnnecessary scanning, biopsiesAnxiety, fear, worry

False positiveFor 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

Digital vs Film mammographyAccuracy of digital mammography is higher especially inWomen under age of 50Dense breastsPremenopausal or perimenopausal women

Etta D. Pisano et al. NEJM Oct2005

NHS Breast cancer screening programmeSince 19981.3 million women being screened each yearAbout 1 in 8 women screened regularly by the NHSBCP will be recalled for assessment at least once over 10 yearsCancers in screened women are smaller and less likely need mastectomy

NHS Breast cancer screening programmeOne fewer women will die from breast cancer for every 400 women screened regularly by the NHSBCP over 10-year periodCurrently NHSBCP saves ~1400 lives each year in UKSpends about 3000 for every year of life saved

NHSBSP Publication no 61 Feb 2006

Situation in Hong KongNo population screening for breast cancerLower incidence compared with Western countriesThe value of mammography screening may be lower than Western countriesNo 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 ContinentsInternational Agency for Research on Cancer and the International Association of Cancer Registries, World Health Organisation, Lyon.

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

Local data from KWHOpportunistic screening5 year period31378 asymptomatic women46637 mammograms performed2 views, double readingCrude cancer detection rate 5 per 1000Lui CY et al. Hong Kong Med J Apr 2007

FutureIncreasing breast cancer awarenessOpportunistic screening services

ConclusionsIncreasing breast cancer incidence in HKHeightened public health awarenessEver-increasing demand for quality breast screeningNot only detect cancerDetecting early cancers leading to better prognosis Feasibility of treatment with less morbidityPopulation screening?

The EndThank you!