Differences in breast cancer survival and stage by age in off-target screening groups: a population-based retrospective study

Age is an important prognostic factor in breast cancer. The target age to screen is under debate. This study aimed to assess the influence of age on the diagnosis and survival among women with breast cancer. This was a retrospective cohort study of the Population-Based Cancer Registry of Campinas, Brazil, and included all women diagnosed from 2010 to 2014. The outcomes assessed were overall survival and stage. For statistical analyses, the Kaplan-Meier method, log-rank tests, and chi-square tests were used. The sample comprised 1741 women aged 40 to 79 years. Diagnoses at stages 0 to II were the more frequent. In the 40 to 49 years and 50 to 59 years age groups, the frequency of stage 0 (in situ) was 20.5% and 14.9% (P=.022), respectively, and the frequency of stage I was 20.2% and 25.8% (P=.042), respectively. The mean overall survival was 8.9 years (8.6–9.2) in the 40 to 49 years age group and 7.7 years (7.3–8.1) in the 70 to 79 years age group. The 5-year overall survival was higher in the 40 to 49 years age group than in the 50 to 59 years age group for stage 0 (in situ) (100.0% vs 95.0%; P=.036) and stage III (77.4% vs 66.2%; P=.046) diagnoses. The 5-year overall survival was higher in 60 to 69 years age group than in the 70 to 79 years age group for stages I (94.6% vs 86.5%; P=.002) and III (83.5% vs 64.9%; P=.010). In all age groups, significant differences in survival were not observed for stage 0 (in situ) vs stage I diagnoses, stage 0 vs stage II diagnoses, and stage I vs stage II diagnoses. Women aged 40 to 49 years had the highest proportion of in situ tumors, and stages III and IV accounted for about one-third of the cases in all age groups. There was no difference in the overall survival for stage 0 (in situ) vs stage I or II diagnoses in all age groups.