Here is the design of a clinical trial:

Official Title: Facilitate and Sustain Return to Work After Breast Cancer: Randomized Controlled Trial

Included conditions:
- Breast Cancer

Study Armgroups:
- {'label': 'Control group', 'description': 'After inclusion, patients will receive standard care. Women allocated in this group will have the standard care.'}
- {'label': 'FASTRACS intervention group', 'description': 'Women allocated in the FASTRACS intervention group will follow a structured care pathway comprising three successive steps (end of chemotherapy interview with a nurse, transitional visit with their GP, pre-RTW visit with their OP), plus one optional step (late visit with an OP- RTW to work coordinator). Four tools will be used during the intervention (RTW guide or checklist for the patient, the GP, the OP and the employer).', 'interventionNames': ['Behavioral: FASTRACS intervention']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'FASTRACS intervention', 'description': 'Intervention (4 steps) :\n\n* Penultimate to last chemotherapy : patient will receive tools of the intervention\n* 1 month after the end of oncological treatment (OT): patient will attend a general medicine consultation with the GP RTW checklist\n* 2 months after OT: patient will attend a pre RTW visit with the OP RTW checklist\n* 5 months after the end of OT: if the patient has not returned to work 10 months after inclusion, they will have a visit with an OP-RTW to work coordinator\n\nSelf-questionnaires will evaluate quality of life (EORTC QLQC30, BR23, Euroqol (EQ-5D-5L)), anxiety and depression (HAD), employment status, self-efficacy to return to work (RTW-SE11), pre-RTW and RTW visit with the OP, social support, care consumption, physical activity (short IPAQ), perceived performance (WRF), work conditions. The implementation and use of the intervention tools will also be assessed: the patient guide, the employer guide, RTW checklists for the GP and the OP.', 'armGroupLabels': ['FASTRACS intervention group']}

Primary Outcomes:
- {'measure': '(a) a sustained return to work between inclusion and 12 months after oncological treatments; and (b) the number of days on sick leave between inclusion and 12 months after oncological treatments .', 'description': 'The main analysis of the primary endpoint will be based on the net benefit of the intervention, estimated using the generalized pairwise comparison method', 'timeFrame': '12 months after oncological treatments (radiation therapy, or chemotherapy for patients without radiation therapy)'}

Please estimate the sample size based on the assumption: 
Two-sided alpha risk of 5%, power of over 80%, and a 5% attrition rate.
Sample size
        We assumed that 75% of patients in the control group would return to work permanently [10] and that among these patients, the average number of days off work in the first year would be 60 days. The number of days off work was simulated using a beta distribution. The study was calibrated to detect an improvement in the FASTRACS intervention group, with 85% of patients returning to work permanently, including a reduction in the average number of days off work for medical reasons to 55 days. 5000 trials were simulated with âRâ 3.3.1 software to evaluate the expected performance of our study according to these hypotheses. The results showed that an enrolment of 400 patients would make it possible to demonstrate a statistically significant net benefit at a two-sided alpha risk of 5%, with a power of over 80%. Assuming a 5% attrition rate, 420 patients would need to be randomised (210 patients per group).