Projected impact of the trend toward delayed childbearing on breast cancer incidence in the Saarland/FRG.

The potential impact of the trend toward delayed childbearing or nulliparity on future breast cancer incidence is quantitatively assessed for the Saarland/FRG. Distribution of age at first birth is estimated from vital statistics for seven five-year birth cohorts from 1936-40 to 1966-70. Estimates of the relative risks associated with age at first birth or nulliparity are based on median results of 23 controlled epidemiologic studies conducted in Europe and North America. Compared to the birth cohorts around 1940, a steady increase in incidence up to about +15% is projected for the younger cohorts indicating a substantial public health impact. Using data of the population based cancer registry of the Saarland, the cumulative incidence of breast cancer up to age 50 is calculated as 1.52% for the 1936-40 birth cohort and is projected to rise to 1.75% in the 1966-70 cohort. Similar changes in fertility patterns have been observed in other parts of the FRG. Given the continuing rise in mortality from breast cancer in the FRG this stresses the need for more effective screening procedures.