The increasing number of breast cancer cases may induce longer waiting times (WT), which can be a source of anxiety for patients and may play a role in survival. The aim of this study was to examine the factors, in particular socio-economic factors, related to treatment delays. Using French Cancer Registry databases and self-administered questionnaires, we included 1,152 women with invasive non-metastatic breast cancer diagnosed in 2007. Poisson regression analysis was used to identify WTs' influencing factors. For 973 women who had a malignant tissue sampling, the median of overall WT between the first imaging procedure and the first treatment was 44 days (9 days for pathological diagnostic WT and 31 days for treatment WT). The medical factors mostly explained inequalities in WTs. Socio-economic and behavioral factors had a limited impact on WTs except for social support which appeared to be a key point. Better identifying the factors associated with increase in WTs will make it possible to develop further interventional or prospective studies to confirm their causal role in delay and at last reduce disparities in breast cancer management.