The South Australian Breast X-Ray Service: results from a statewide mammographic screening programme.

The South Australian Breast X-Ray Service is a centralised breast cancer screening programme in the State of South Australia. In its first 5 years of operation nearly 100 000 screens were performed. This study reports the clinical performance of the programme and compares it with other published series. Women aged 40 years and over were screened with two-view mammography every 2 years. Radiologists double-read the screening films and multidisciplinary teams assessed the recalled women at a single centre. In the prevalent round 76 106 women were screened, and subsequently 21 506 of them were rescreened. The recall rate for further investigation was 4.9% in the prevalent round and 2.4% in the incident rounds. The cancer detection rate per 1000 women was 7.0 in the prevalent screening round and 3.4 in the incident rounds. Forty-two per cent of invasive carcinomas measured < or = 10 mm in the prevalent screening round and the median tumour size was 12 mm. The benign to malignant biopsy ratio was 1:1.4 in the prevalent round and 1:2.8 in the incident rounds. In the prevalent round 77% of invasive tumours were lymph node negative and this proportion increased to 86% in the incident rounds.