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Summary Background The Edinburgh randomised trial of breastcancer screening recruited women aged 45–64 years from 1978 to 1981 (cohort 1), and those aged 45–49 years during 1982–85 (cohorts 2 and 3). Results based on 14 years of follow-up and 270 000 woman-years of observation are reported. Methods Breast-cancer mortality rates in the intervention group (28 628 women offered screening) were compared with those in the control group (26 026) with adjustment for socioeconomic status (SES) of general medical practices. Rate ratios were derived by means of logistic regression for the total trial population and for women first offered screening while younger than 50 years. Analyses were by intention to treat. Findings Initial unadjusted results showed a difference of just 13% in breast-cancer mortality rates between the intervention and control groups (156 deaths [5·18 per 10 000] vs 167 [6·04 per 10 000]; rate ratio 0·87 [95% CI 0·70–1·06]), but the results were influenced by differences in SES by trial group. After adjustment for SES, the rate ratio was 0·79 (95% CI 0·60–1·02). When deaths after diagnosis more than 3 years after the end of the study were censored the rat ratio became 0·71 (0·53–0·95). There was no evidence of heterogeneity by age at entry and no evidence that younger entrants had smaller or delayed benefit (rate ratio 0·70 [0·41–1·20]). No breast-cancer mortality benefit was observed for women whose breast cancers were diagnosed when they were younger than 50 years. Othercause mortality rates did not differ by trial group when adjusted for SES. Interpretation Our findings confirm results from randomised trials in Sweden and the USA that screening for breast cancer lowers breast-cancer mortality. Similar results are reported by the UK geographical comparison, UK Trial of Early Detection of Breast Cancer. The results for younger women suggest benefit from introduction of screening before 50 years of age.

In the Edinburgh Breast Screening Project 210 cancers were detected from commencement in 1979 up to December, 1984. By this time the full initial cohort had completed at least 3 visits and a proportion had attended for up to 5 visits, so pathological characteristics for prevalent and incident cancers could be compared. The main differences are in distribution of histological type of cancer, detection of occult invasive disease, and lymph-node positivity among incident tumours. Only the first of these was statistically significant. This evaluation shows that cancer detection by screening in Edinburgh conforms with screening theory, in which detection of good prognosis tumours is favoured at the prevalence screens, and faster growing, aggressive tumours are found at the incidence screens. Qualitative histopathology may provide a better measure than standard quantitative judgments of size and lymph node status to compare the varieties of cancer detected by screening programmes and to understand the biology of the disease.

An approach to the management of patients with large (greater than 4 cm) operable breast cancers is described. The conventional sequence of mastectomy followed by systemic therapy is reversed, allowing accurate measurements of response to individual forms of endocrine therapy or chemotherapy. Such a method not only permits individual selection of appropriate systemic therapy, but also allows clinical response to be related to histological and biochemical tumour parameters. A response was observed in eleven of twenty-three patients to endocrine treatment and in twelve of thirteen to combination chemotherapy. In five of the latter the response was histologically complete.