Impact of socioeconomic status on stage at diagnosis of breast cancer

BackgroundThis study aimed to evaluate the potential impact of social inequalities on stage at diagnosis and long-term outcome of breast cancer patients attending the Institut Curie in Paris (France).MethodsThe study population included 14,610 breast cancer patients diagnosed and treated in the Institut Curie between 1981 and 2001. The socioeconomic status was determined from district of residence, median income for town of residence corrected by the consumption unit and body mass index. Logistic regression models adjusted on socioeconomic factors were used to evaluate clinical and pathologic features at diagnosis. Overall survival and distant metastasis were analysed with log-rank tests and Cox proportional hazards regression models.ResultsPatients living in lower income districts were more likely to be diagnosed with breast tumors size greater than 20 mm (P = 0.01). Residents of high-income urban areas (> 15,770 €) exhibited a significant overall survival and distant metastasis advantage (respectively HR = 0.93 [0.86–0.99]; P = 0.02 and HR = 0.91 [0.85–0.98]; P = 0.01). Breast cancer screening with mammography was independent of district of residence (P = 0.61) or income (P = 0.14). After adjusting for age at diagnosis and period, the risk of having breast cancer with unfavorable prognostic factors such as tumor size greater than 20 mm decreased with 1000 € increase in district income (OR = 0.986 [0.98–0.99]; P < 0.001). Similarly, the risk of cancer death decreased for patients residing in districts with median income greater than 15,770 € (HR = 0.92 [0.86–0.98]; P = 0.01).ConclusionDespite the limitations of the study (aggregate data used to assess socioeconomic status, non representative cohort of French women), we observed that poorer breast cancer prognosis with advanced disease diagnosis and increased risk of breast cancer mortality was related to low socioeconomic status.