Here is the design of a clinical trial:

Official Title: Tailored Axillary Surgery With or Without Axillary Lymph Node Dissection Followed by Radiotherapy in Patients With Clinically Node-positive Breast Cancer (TAXIS). A Multicenter Randomized Phase III Trial (OPBC-03/ SAKK 23/16 /IBCSG 57-18 / ABCSG-53 / GBG-101)

Included conditions:
- Node-positive Breast Cancer

Study Armgroups:
- {'label': 'ALND', 'type': 'ACTIVE_COMPARATOR', 'description': 'Tailored axillary surgery followed by axillary lymph node dissection (ALND) and regional nodal irradiation excluding the dissected axilla.', 'interventionNames': ['Procedure: Tailored axillary surgery - both Arms', 'Radiation: Radiotherapy - Arm A']}
- {'label': 'No ALND', 'type': 'ACTIVE_COMPARATOR', 'description': 'Tailored axillary surgery followed by regional nodal irradiation including the full axilla.', 'interventionNames': ['Procedure: Tailored axillary surgery - both Arms', 'Radiation: Radiotherapy - Arm B']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Tailored axillary surgery - both Arms', 'description': 'Axillary lymph node dissection - Arm A', 'armGroupLabels': ['ALND', 'No ALND']}
- {'type': 'RADIATION', 'name': 'Radiotherapy - Arm A', 'description': 'Regional nodal irradiation excluding the dissected axilla - Arm A', 'armGroupLabels': ['ALND']}
- {'type': 'RADIATION', 'name': 'Radiotherapy - Arm B', 'description': 'Regional nodal irradiation including the full axilla - Arm B', 'armGroupLabels': ['No ALND']}

Primary Outcomes:
- {'measure': 'Disease-free survival (DFS)', 'description': 'The primary endpoint of this trial is DFS, defined as time from randomization until one of the following events, whichever comes first:\n\n* Local recurrence, regional recurrence, distant recurrence\n* Second breast cancer\n* Death from any cause Patients not experiencing an event will be censored at the date of the last available assessment.', 'timeFrame': 'at the occurrence of the event or latest 20 years after randomization of the last patient'}

Please estimate the sample size based on the assumption: 
Type I error of 5%, power of 80%, one interim analysis for efficacy/futility after 20% of the required events, and analysis based on the per-protocol set.
Sample size considerations and statistical analyses
        The sample size is based on the primary endpoint DFS. With a type I error of 5% and a power of 80%, 385 events will be needed to show non-inferiority of TAS and axillary RT in comparison to ALND with a non-inferiority hazard ratio of 1.289 (corresponding to a DFS at 5Â years of 80% in the ALND arm and 75% in the TAS and axillary RT arm). The sample size needed is 1500 patients (750 per arm). One interim analysis for efficacy/futility is foreseen after 20% of the required events have occurred. A report including the interim efficacy results as well as patient characteristics, treatment administration and safety results (AEs, SSI, and serious AEs) will be presented to an independent Data Monitoring Committee appointed by the SAKK Board. The SAKK Board will decide on the continuation/modification/early stopping of the trial based on the recommendations of the committee. All efficacy endpoints will be analyzed based on the per-protocol set. For the primary endpoint, DFS, the hazard ratio and one-sided 95% confidence interval will be calculated using a Cox regression model with the treatment arm as independent variable and the stratification factors as strata. The median DFS and the corresponding 95% confidence intervals using the Kaplan-Meier method will be presented for each treatment arm.
        Planned subgroup analyses for the primary endpoint:Type of positive node detection at first diagnosis: cN1 vs. iN1Neoadjuvant vs. adjuvant systemic treatment vs. bothycN1 vs. ycN0BMI <â25 kg/m2 vs â¥â25 kg/m2Normofractionation vs. hypofractionationBreast-conserving surgery vs. mastectomyTriple-negative vs. HER2+ vs. ER- and/or PR-positive, and HER2-