Evolution of breast cancer screening in countries with intermediate and increasing incidence of breast cancer

Abstract

Background: Few studies have been published regarding the practice of breast cancer screening in Asian countries.

Aims: The present study illustrates how the health policy for breast cancer screening has evolved in Taiwan from selective mammographic screening within a high-risk group, firstly to a programme of physical examination by public health nurses, and finally to a two-stage breast cancer screening programme, with a risk assessment followed by mammography for those at moderate to high risk.

Data sources: Breast cancer screening has evolved from 1995 to 2004 in Taiwan in three stages: (1) selective screening for breast cancer with mammography, ultrasound and physical examination only in first-degree relatives of breast cancer cases (1995-1998); (2) a programme of mass screening (1999-2001) with physical examination by public health nurses; and (3) two-stage breast cancer screening with a risk factor questionnaire and mammography for those deemed at moderate-to-high risk (2002-2004). The questionnaire was based on significant risk factors in a previous epidemiological study, in conjunction with the physical examination programme, a risk score was constructed from the logistic regression coefficients from the previous study, and women with a score above the median in the previous epidemiological study were assigned to mammography.

Results: Two-stage mammography screening had the most favourable results compared with the two previous screening regimes. It had a positive predictive value of recall after mammography of 14%, compared with 8% for selective screening and 2% for physical examination. Of screen-detected cancers in the two-stage programme, 71% were either ductal carcinoma in situ or stage T1, compared with 61% for selective screening and 60% for physical examination. The area under the receiver operating characteristic curve was 71% for the two-stage programme.

Conclusions: For a low- to medium-risk country such as Taiwan, two-stage screening has acceptable parameters of recall and cancer detection, and compares well with other screening strategies.