Objective: To analyze the population-based survival of breast cancer (CM) diagnosed in early stages estimating the time trends of excess mortality (EM) in the long term in annual and five-year time intervals, and to determine, if possible, a proportion of patients who can be considered cured.
Method: We included women diagnosed with BC under the age of 60 years in stages I and II in Girona and Tarragona (N = 2453). The observed (OS) and relative survival (RS) were calculated up to 20 years of follow-up. RS was also estimated at annual (RSI) and in five-year intervals (RS5) to graphically assess the EM. The results are presented by age groups (≤49 and 50-59), stage (I/II) and diagnostic period (1985-1994 and 1995-2004).
Results: In stage I, OS and RS were higher during 1995-2004 compared to 1985-1994: 3.5% at 15 years of follow-up and 4.5% at 20-years of follow-up. In 1995-2004, the OS surpassed 80% in stage I patients whereas in stage II it remained below 70%. During 1995-2004, the long-term EM did not level off towards 0 (RSI <1) independently of age group, stage and period of diagnosis. After 15 years of follow-up, the 5-year EM oscillated between 1 and 5% in stage I (RS5 ≥0.95) and between 5 and 10% in stage II.
Conclusions: In our cohort, after 15 years of follow-up, it was detected that the annual EM did not disappear and the five-year EM remained between 1 and 10%. Therefore, it was not possible to determine a cure rate of BC during the study period.
Keywords: Breast cancer; Conditional survival; Curación; Cáncer de mama; Exceso de mortalidad; Excess mortality; Supervivencia; Supervivencia condicional; Survival; “Cure” fraction.
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