[The evolution and prediction of the incidence of breast cancer in Zaragoza, 1961-2000].

BACKGROUND

Using the data available from the Cancer Registry of Zaragoza, the incidence of breast cancer in women from 1961 to 1985 was analyzed with future evolution being predicted up to the year 2000.

METHODS

The age, period and birth cohort effects, in addition to the place of residence (capital/rest of province) were analyzed using both, graphic analysis techniques and multivariate models of incidence rates by the Poisson regression. Assuming a constant period effect, the age and cohort effects were used to predict incidence rates in a period of 15 years between 1986 and 2000.

RESULTS

Age-standardized incidence rates increased from 17.1 cases per 100,000 women per year in 1961-1965 to 36.5 in 1981-1985. This increase was mainly observed in women above the age of 40 residing in an urban environment. In a graphic analysis of rates by birth cohorts, an age and cohort effects were observed, producing an anticipation of age to which the highest values in incidence rates were reached. In the prediction of incidence with multivariate models, and increase is foreseen up to the year 2000.

CONCLUSIONS

An increase of breast cancer incidence in Zaragoza has been observed with a further increase foreseen up to the year 2000. This increasing incidence has been related to the age, the year of birth and the place of residence of cases. A relation with some other determinants of disease, and whether the results observed may be extrapolated to the rest of Spain are discussed.