Survival and prognostic factors of breast cancer in women in the state of São Paulo

Abstract

Introduction: Breast cancer is the first most common malignancy in the female population worldwide. Monitoring the survival of women with breast cancer has been a strategy often adopted at the international level as a measure to assess public policy progress for disease control. Objectives: To estimate the probability of five-year survival and to investigate the prognostic factors of women with breast cancer included in the São Paulo State Cancer Hospital Records Base (RHC-SP), established in 2000 and maintained by the Oncocentro Foundation of São Paulo (Fundação Oncocentro de São Paulo – FOSP). Material and methods: This is a historical cohort. The sample consisted of women with breast cancer diagnosed between 2002 and 2012 and included in the RHC-FOSP. The event studied was specific mortality from breast cancer. Live cases at the end of follow-up (December 31st, 2017), loss of follow-up and those who died from causes other than breast cancer were considered censures on the date of the last contact or date of death. Survival analysis was performed using the Kaplan-Meyer method and the survival curves were compared using the log-rank test. Hazard ratios (HR) and respective 95% confidence intervals (95%CI) were also estimated using the Cox's proportional hazards model. This study was approved by the Human Research Ethics Committee of the School of Medicine of Botucatu, UNESP. Results: In the period between 2002‒2012, 53,146 cases of invasive breast cancer were registered at RHC-FOSP. The median age of women at diagnosis was 55.9 years. By the end of the follow-up (December 31st, 2017), 20,683 patients died and 71.4% were due to breast cancer. The probability of specific survival for the entire cohort at 5 and 10 years was 76.1% (95%CI 75.7‒76.5%) and 64.8% (95%CI 64.2‒65.3%), respectively. In the multivariate analysis, the factors associated with the prognosis were: age at diagnosis, year of diagnosis, educational level, grouped clinical stage and histological type. Conclusion: Specific survival for breast cancer in the state of São Paulo is significantly associated with several characteristics. The knowledge of these characteristics can contribute to the development of public policies in the area.