Characteristics and prognosis of young breast cancer patients treated in a public comprehensive cancer centre in Brazil: A retrospective cohort study.

Background: The incidence of breast cancer among women under 41 years old varies worldwide, with higher rates observed in developing countries. These young women often face later-stage diagnoses. In this study, we examine a cohort of young women who were treated for breast cancer in São Paulo, Brazil.

Methods: We conducted a retrospective cohort study involving women under 41 years old. Our objective was to describe patient and treatment characteristics, with the main outcomes being overall and disease-free survival. Our analysis explored the associations between age of menarche, history of breastfeeding, use of hormonal contraceptives, and age at diagnosis.

Results: Our study included 493 patients with a mean follow-up of 62.8 months. The mean age of the patients was 34.6 (SD=4.19). Of the patients, 68% presented with locally advanced disease, and 19.27% were metastatic at the time of diagnosis. We observed significant associations between age of menarche and age at diagnosis (p = 0.0096), as well as age at diagnosis and breastfeeding (p = 0.0232). Chemotherapy was administered to 92.91% of the patients as part of their treatment, while 27.2% were eligible for breast-conserving surgery. During the follow-up period, 153 patients died, with disease progression being the cause of death in 73.2% of cases. The median survival time for the entire cohort is still under review, while the metastatic patients at diagnosis had a median survival time of 28.64 months (95%CI 20.21-40.89).

Conclusion: Our findings highlight significant associations between late-stage diagnosis and overall and disease-free survival in this patient age group. Given that the majority of patients present with locally advanced breast cancer, it is crucial to implement strategies that promote early-stage diagnosis and improve survival rates.