Breast cancer is the commonest malignancy among women in most European countries. Given current patterns of occurrence by age, about one in 12 women will develop the disease before the age of 75 years (lifetime risk around 8%), and it typically accounts for 20% or more of all cancers in women [1]. Breast cancer is thus a major public health problem, but with the exception of oral contraceptives and hormonal replacement therapy [2,3], both of which also have clear benefits, the known major risk factors are not amenable to primary prevention. Mass screening of women over age 50 years by mammography has been shown to reduce mortality [4]; national mammographic screening programmes were introduced for women aged 50-64 years in the UK from 1988 [5] and for women aged 50-70 years in The Netherlands from 1990 [6], and a regional scheme in Denmark was started in 1991 [7]. Opportunistic screening is also widespread in many European countries. The incidence of breast cancer has been increasing in many countries [1,[8][9][10][11]], but the available treatments have improved [12], survival has improved [13,14] and mortality has begun to decline [15].Until recently, international comparisons of regional or national survival estimates within Europe were bedevilled by the lack of comparability of data and methods. Within the past 5 years, however, evidence of international differences in survival from breast cancer [16][17][18] (and many other cancers) in Europe has begun to emerge from the EUROCARE (European Cancer Registry-based study of survival and care of cancer patients) study. (The author has been a member of the EUROCARE Project Management Group since 1989, and is a co-author of various publications emanating from the project.) In this article, the evidence for these differences in breast cancer survival among women in Europe is reviewed, and some of the possible explanations are considered, with particular reference to the patterns of survival in the UK and the extent to which they differ from those of other countries in Europe.The EUROCARE study now covers 17 European countries and is the largest international study of cancer survival. It includes 3.5 million cancer patients who were diagnosed between 1978 and 1989, and who have been followed up for at least 5 years, until the end of 1994 [19]. Data supplied in a standard format by 45 cancer registries covering a total population of about 100 million have been subjected to central quality control and analyzed using standard methods [20]. Relative survival up to 10 years after diagnosis by age, sex and country has been estimated for each of 45 cancers in adults aged 15-99 years at diagnosis.For women diagnosed with breast cancer during the period 1978-1985, 5-year survival in 12 countries up to the end of 1990 ranged from 76% in Switzerland to 44% in Poland (Fig. 1a). In Switzerland and Finland, survival was significantly higher than the weighted European average for participating countries, and significantly lower in England, Scotland, Estonia and Poland [16].Detaile...