Clinical factors associated with survival of women with breast cancer in southeastern Brazil: a retrospective cohort study

Introduction: Considering that breast cancer is the most common cancer in women worldwide, it is estimated that there will be approximately 2.3 million new cases and 685,000 deaths in 2020. In Brazil, 73,610 new cases of breast cancer were estimated in 2023, with an estimated risk of 66.54 cases per 100,000 women. Survival analysis is essential to assess the effectiveness of available treatments and identify areas for improvement. Without survival data, it is difficult to measure the impact of current treatments and health policies on patients’ longevity and quality of life.

Objective: To study the association between clinical factors and survival among women diagnosed with breast cancer in all hospitals that comprise the Oncology Care Network of a state in Southeastern Brazil.

Method: An observational retrospective cohort study was conducted using secondary data from the Cancer Hospital Registries and the Mortality Information System of Brazil, with a sample consisting of 12,096 women diagnosed with breast cancer between 2000 and 2016. Kaplan-Meier methods were used to evaluate 5-year survival, and the LogRank test was used for univariate analysis of clinical variables. Multivariate analysis was performed using the Cox proportional hazards model for specific causes.

Results: Our hospital cohort identified 12,096 cases of breast cancer. The mean age was 54.67 years. Most women (43.11%) had no previous diagnosis and treatment, and invasive ductal carcinoma was the most common type of cancer (96.49%). Women with initial and in situ stage (OS = 0.996; 95% CI: 0.990-1.000) and stage I (OS = 0.972; 95% CI: 0.965-0.979) had higher overall survival compared to women with advanced stage IV (OS = 0.323; 95% CI: 0.314-0.374; p < 0.001). In the multivariate analyses, women from the private healthcare system showed a reduced risk of mortality (HR: 0.837; 95% CI: 0.750-0.934; p = 0.001) compared to those referred from the public network. Women with distant metastases had a 49% higher risk of mortality (HR:1.49; 95% CI: 1.143-1.948; p = 0.003) compared to women without stage IV disease.

Conclusion: Women with advanced stage cancer, tumor bilaterality, and isolated treatments had a higher risk of mortality. Mammography and other screening methods improved prognosis and survival. Urgent public investment is needed for screening, early detection, and timely cancer treatment.

Corresponding author: Luís Carlos Lopes-Júnior (e-mail: lopesjr.lc@gmail.com).