Changing trends. An overview of breast cancer incidence and mortality.

The incidence of breast cancer rose about 1% per year between 1940 and 1980 according to data in the Connecticut Tumor Registry. A sharp increase of 32% was reported between 1980 and 1987 in the Surveillance, Epidemiology and End Results Program of the National Cancer Institute. Data from this program shows that the increase in incidence was due to localized cases and cancers of less than 2 cm in greatest dimension. In addition, a sharp increase in carcinoma in situ was observed. The increase in breast cancer incidence coincides with an increased use of mammography in asymptomatic women in the 1980s. Mortality from breast cancer has changed little since the 1930s, but the increases in localized and small-size tumors and decreases in the rate of tumors of 3 cm or larger at diagnosis indicates that breast cancer mortality may start to decrease. Evidence from provisional breast cancer monthly mortality data suggests that there was a 3-6% drop in 1991 compared to 1990.