BREAST-CANCER IN DENMARK - INCIDENCE, RISK-FACTORS, AND CHARACTERISTICS OF SURVIVAL

In Denmark, incidence of female breast cancer remained constant from 1 943 to around 1960, whereafter a steady increase has occurred, the lev el today being about 50% higher than in 1960. No equivalent rise has b een observed for breast cancer mortality. Influence of hormonal and di etary factors on breast cancer risk and survival was evaluated in a co mbined population-based case-control and follow-up study, including 2 445 women, aged less than 70 years, diagnosed with breast cancer in De nmark between 1 March 1983 and 31 August 1984, identified from the fil es of the nation-wide clinical trial of the Danish Breast Cancer Co-op erative Group (DBCG) and the Danish Cancer Registry. The control group was an age-stratified random sample of the general female population, selected from the Central Population Register. Data on risk factors w ere collected by self-administered questionnaires. Clinical and pathol ogical tumour characteristics derived from DBCG. The case-control anal ysis confirmed an overall increased risk of breast cancer associated w ith urban residence, high social status, nulliparity, early age at men arche, late age at natural menopause, hormonal replacement therapy, hi gh dietary fat intake, and high alcohol consumption in a subgroup. It failed to detect an association with age at first childbirth, oral con traceptives, smoking, intake of vegetables, tea, coffee, and sweetener s. Survival was determined by tumour size, skin invasion, number of po sitive lymph nodes, and grade. There was no relation between survival and reproductive or hormonal factors, dietary variables, alcohol consu mption, or smoking. However, a complex relationship may exist between survival and body mass index.