Variations in breast cancer incidence per decade of life (Goiânia, GO, Brazil): 16-year analysis.

OBJECTIVE

To analyze the variation in breast cancer incidence, with stratification into ten-year age groups, 17 years after the nuclear accident in Goiânia.

METHODS

Between 1988 and 2003, 3312 new cases were recorded. The crude and standardized incidence rates were calculated. ANOVA was used to obtain the coefficient of determination (R2) for the incidence over the course of the years, and p-values were obtained both by linear and by polynomial regression.

RESULTS

The increases in crude and standardized incidence were statistically significant in all age groups, except for women between 20 and 29 years old. For the age group from 30 to 49 years, the increase in incidence was around 100% (p = 0.001), and from 50 to 59 years, 277% (p < 0.001). More modest increases of around 50% were observed in the age groups from 60 to 79 years (p = 0.013). For the women aged 80 years and over, the increase was 272% (p = 0.015).

CONCLUSIONS

There were significant increases in the crude and standardized incidence rates for breast cancer in the city of Goiânia. The women in the age group from 50 to 59 years were the ones who presented the highest increase in incidence. More wide-ranging epidemiological studies therefore become necessary for defining the factors that are possibly related to this excessive increase in breast cancer incidence, in certain specific segments of the female population.