An analysis of factors associated with interval as opposed to screen-detected breast cancers, including hormone therapy and mammographic density.

A comparison of 270 interval breast cancers in South Australian women aged 50 years and over with 628 age-matched screen-detected cases indicated that the former had more advanced stages (P<0.001), higher grades (P<0.001), and more frequently a history of past breast problems (P<0.027). After adjusting for these factors, and presence of a self-reported breast lump at the last screen, using conditional logistic regression, hormone replacement therapy (HRT) exposure in the 6 months prior to this screen had a raised relative odds (95% CL) of an interval cancer of 1.48 (1.02, 2.14). For 479 women where breast density was measured, high density showed an elevated relative odds of an interval cancer of 2.62 (1.71, 4.02). The relative odds of a high density was raised to 2.02 (1.33, 3.06) when the HRT history was positive. Screeners should be aware when there is a history of HRT or past breast problems, or a high breast density, that there is an increased probability of a subsequent interval cancer.

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.