Age at Diagnosis, Extent of Disease and Breast Cancer Survival: A Population-Based Study in Florence, Italy

Abstract

Background: The effect of age at diagnosis on the prognosis of breast cancer is still controversial. The study described the variation by age at diagnosis of some clinical-pathologic features and evaluated the relationship between age and survival, taking into account the effect of extent of disease. Materials: The study comprised a large population-based series of 1,182 invasive breast cancers, incident in the period 1985–1986 in the province of Florence. Results: The proportion of cases without nodal involvement progressively lowered from 59% in the age group ≤39 years to 22% in the age group ≥80 years. The extent of disease was unknown in 14% of cases aged 70–79 years and in 43% of those aged ≥80 years (other age groups: 3%–5%). A lower rate of surgical treatment and axillary surgery were the main reasons for inadequate staging in the elderly. Ten-year observed survival progressively decreased from 71% for age ≤39 years to 12% for age ≥80 years. Ten-year relative survival showed less evident differences, dropping from 72% for age ≤39 years to 57% for age ≥80 years. In the relative survival analysis, the differences in relative risks of death among age groups were not significant, either in the univariate or multivariate analysis. Nevertheless, the model with adjustment for extension of disease showed a flattening of the estimated relative risks in age groups over 59 years. Conclusions: Age at diagnosis was not significantly related to 10-year breast cancer relative survival, suggesting that the worse prognosis in the elderly was largely related to the risk of death from other causes, rather than to a different malignant potential of the tumor. The worse distribution by extent of disease in older women indirectly suggested that diagnostic delays also influenced the different prognosis observed among age groups.