Incidence of female breast cancer in relation to prevalence of risk factors in Denmark.

The extent to which changes in prevalence of risk determinants for female breast cancer could explain the temporal variation in incidence was examined using incidence figures from Denmark for the years 1943-1989. Significant increases in incidence were observed for more recent time periods and birth cohorts. Using deviance statistics from Poisson regression measures of variability explained, only a small proportion of the increase in incidence could be accounted for by fertility rates, average age at menarche and exposure to exogenous hormones. Dietary factors, on the other hand, accounted for the greater proportion of the variation observed by time period or birth cohort. In particular, there was a strong positive association of incidence with alcohol consumption and a negative association with carbohydrate intake.