Opportunistic breast cancer screening in Hong Kong; a revisit of the Kwong Wah Hospital experience.

OBJECTIVE To analyse the performance of opportunistic breast screening in local Well Women Clinics during the 5-year period from 1998 to 2002, with reference to international as well as our own earlier experience (1991 to 1993 to 1995). DESIGN Prospective study. SETTING Well Women Clinics in regional Hong Kong hospitals. PARTICIPANTS Women attending the Well Women Clinics of the Tung Wah Group of Hospitals for breast cancer screening. MAIN OUTCOME MEASURES All screening-detected breast cancers. RESULTS After 46 637 screening mammograms and excluding palpable masses detected by the patients themselves, 232 women were detected with cancers, yielding a crude detection rate of 5.0 per 1000. Age range for cancer detection was 35 to 72 (median, 49) years. Clinic staff detected palpable lumps in 83 patients, constituting 36% of the detected cancers, of which 15 (6.5% of all detected cancers) were not identified by mammography. The cancer detection rate was 5.9 per 1000 in the age-group 40-49 years and 3.7 per 1000 in those 50 years or older. The cancer detection rate was 58.5 per 1000 in the high-risk group (aged <40 years with positive family history). The minimal cancer detection rate was 2.2 per 1000, representing 45% of all cancers whose pathology was available to us. Ductal carcinoma in situ comprised 28% of all such cancers. Our recall rates were 4.6% for additional views only, 3.3% for ultrasound only, and 2.3% for both. Positive predictive values for abnormal mammograms and biopsies were 4.9% and 26.0%, respectively. CONCLUSION Mammographic screening has been reported to reduce mortality up to 35% in western countries. However, data concerning Asian Chinese populations are meagre. Our Well Women Clinics pioneered large-scale self-referred breast screening in Hong Kong. Despite the lower incidence of breast cancers than in Occidental populations, our screening programme performed comparably to those in the West, and has improved over time. Our screening service for self-referred women detected breast cancers even at an early stage, which facilitated a better prognosis and more treatment options, whilst appearing to be highly acceptable to our community. Besides, it could provide training and expertise in breast radiology and mammography, which are essential prerequisites for establishing population screening.