Female breast cancer in Gipuzkoa: prognostic factors and survival

In Gipuzkoa, screening for breast cancer was initiated in 1997 and in this paper we present breast cancer characteristics and survival for women diagnosed during the pre-screening period.

All cases diagnosed during 1995-1996 were included and the tumour characteristics were analysed. One-, five- and ten-year observed and relative survival (RS) were estimated overall, as well as by age and tumour characteristics. Multiple regression models were used to evaluate the effect of tumour characteristics on ten-year RS.

Six hundred and twenty-two cases with a mean age of 60.7+/-15 years were included. The mean follow-up was 7.5 years (max. 10) with a mortality of 40.5%. Ductal carcinoma accounted for 78% of all cases; almost 50% had good or moderate differentiation and 28% were positive for both hormone receptors studied. Nearly 80% of cases were diagnosed in stage I or II and breast-conserving surgery was employed more often than mastectomy. Age-standardised RS was 77% (95% CI 72.1-82.3) and 68% (95% CI 60.4-74.6), five and ten years after diagnosis respectively. The relative excess risk of death was significantly different only for age, stage and degree of differentiation.

This study shows an increase in survival compared to previous studies in the region. This could be explained by advances in diagnosis and treatment, as demonstrated by younger age and earlier stage at diagnosis and by the therapy profiles. Age and stage were shown to be major predictors of survival in our study and adjustment for the other factors had only limited effects on the risk of death for these two variables.