Introduction : The breast cancer diagnosis, the symptoms and the side effects of the treatments, lead to multiple physical and psychological deficits that can have effects on the professional life. Indeed, with a median age of 63 years at the time of diagnosis, half of the women are still of working age. However, after the diagnosis, all women do not return to work. In order to explain this phenomenon, numerous studies have addressed the sociodemographic, occupational and medical determinants that impact the patients’ return to work ; but these factors alone are not sufficient to explain women's non-return to work. It appears that a number of psychosocial factors may also account for the return to work.Aims : The main objective of this study is to identify the main psychosocial determinants of the return to work of women with breast cancer during the year following the start of their adjuvant treatments. A secondary objective is to understand the impact of changes in these psychosocial determinants on the return to work.Method : We performed a longitudinal and prospective study of 68 patients with a mean age of 46.97 (SD = 6.92), employed at the time of diagnosis of breast cancer, recruited at the Montpellier Institut du Sein (MIS). The women were encountered during an initial measurement, by interindividual maintenance, at the beginning of adjuvant treatments (T0). Subsequently, they were followed by telephone at 3, 6 and 12 months after T0 (T1, T2 and T3, respectively). Socio-demographic, occupational and medical data, precariousness (EPICES score), neuroticism (Neo-PI r), quality of life (QLQ-C30), fatigue (MFI 20), post traumatic development social distress (SDI) and perceived social support (SSHSC) were assessed at T0. At T1, T2 and T3 we observed : being in a couple, providing or not supporting children's studies, collecting toxicities related to medical treatment and returning to work. At T2 and T3 we also assessed : quality of life, post-traumatic development, fatigue, social distress and perceived social support.Results : At T1, 50.0% of patients returned to work ; at T2, 60.7% were back to work ; at T3, 74.5% of them were back to work. Results of logistic regression analyzes indicate that a strong perception of negative support at T0, OR = 0.74 [0.56 - 0.97] and at T3, OR = 0.59 [0.39-0.90], a high sensation of physical fatigue at T3, OR = 0.55 [0.36 - 0.80] and high precariousness, OR = 0.94 [0.89 - 0.99] brake the return to work at T3. On the other hand, a good physical state at T0, OR = 1.17 [1.02 - 1.33] and a good cognitive state at T2, OR = 1.06 [1.01 - 1.11] are levers for returning to work at T3. Otherwise, we observed that overall good health, OR = 1.10 [1.001 - 1.20] and good cognitive status, OR = 1.08 [1.02 - 1.15] at T2, are levers for returning to work at the same time, while an increase in mental fatigue between T0 and T2 decreases the chances of returning to work at T2, OR = 0.13 [0.02 - 0.80]. Finally, the results of our study show that good overall health at T0 is a return to employment lever at T1, OR = 1.05 [1.01 - 1.10].Conclusion : Psychosocial determinants, including social support, precariousness, quality of life and fatigue, can play an important role in predicting the return to work of women with breast cancer. This confirms the interest of a multidisciplinary care of cancer and encourages the emergence of a theoretical model of the job retention, taking into account the socio-demographic, professional, medical, social, physical and psychological characteristics of the patients.