Here is the design of a clinical trial:

Official Title: HYPOfractionated Radiation Therapy Comparing a Standard Radiotherapy Schedule (Over Three Weeks) With a Novel One Week Schedule in Adjuvant Breast Cancer: An Open Label Randomised Controlled Study (HYPORT- Adjuvant)

Included conditions:
- Breast Cancer Female

Study Armgroups:
- {'label': '3 week RT', 'type': 'ACTIVE_COMPARATOR', 'description': 'Adjuvant Radiotherapy delivered over 3 weeks', 'interventionNames': ['Radiation: 3 week RT']}
- {'label': '1 Week RT', 'type': 'EXPERIMENTAL', 'description': 'Adjuvant Radiotherapy delivered over 1 week', 'interventionNames': ['Radiation: 1 week RT']}

Interventions:
- {'type': 'RADIATION', 'name': '3 week RT', 'description': '40 Gy in 15 fractions over 3 weeks to the whole breast or chest wall. Patients undergoing breast conservation therapy will receive additional boost radiotherapy to the tumor bed. The supraclavicular fossa will be treated in patient with node positive disease or those receiving neoadjuvant chemotherapy. IMC and Axillary radiotherapy will be given as per the institutional policy. Boost Dose schedule for BCS patients will be 8 Gy delivered in 15 fractions simultaneously with tangential EBRT. In institutions planning for sequential boost, a dose of 12 Gy in 4 fractions will be delivered after whole breast EBRT.', 'armGroupLabels': ['3 week RT']}
- {'type': 'RADIATION', 'name': '1 week RT', 'description': '26 Gy in 5 fractions over 1 week to the whole breast or chest wall. Treatment volumes will be same as the control arm. Additional boost will be delivered to patients who have undergone breast conservation. Boost Dose schedule for BCS patients will be 6 Gy delivered in 5 fractions simultaneously with tangential EBRT. In institutions planning for sequential boost, a dose of 12 Gy in 4 fractions will be delivered after whole breast EBRT.', 'armGroupLabels': ['1 Week RT']}

Primary Outcomes:
- {'measure': 'Locoregional Recurrence Rate (LRR)', 'description': 'Cumulative proportion of patients with locoregional recurrence', 'timeFrame': '5 years'}

Please estimate the sample size based on the assumption: 
The study assumes a one-sided type I error of 0.025, a power of 80%, and a 2% annual dropout rate. Patients will be accrued over 5 years with a total trial duration of 10 years to ensure a minimum follow-up of 5 years for the last patient.
Sample size {14}
        
          Non-inferiority margin and justification for the same
          Assuming that the locoregional recurrence rate in the control arm is 5%, a non-inferiority margin of 3% is clinically acceptable and corresponds to a hazard rate of 1.63. The choice of the non-inferiority marginis arbitrary to a significant extent and we base it on the guidance that it should not be larger than the expected benefit from adjuvant radiotherapy. A large volume of data is available regarding the benefit of adjuvant radiotherapy in breast cancer patients. In the setting of breast conservation surgery, the EBCTCG meta-analysis demonstrated that use of adjuvant radiotherapy reduced the 5-year local recurrences by 17% after breast conservation surgery [2], while in the postmastectomy setting the 5-year local recurrence was reduced by 14.7% for N+ patients [3]. The START trials were designed to show a difference of 5% as the non-inferiority margin [28]. This is approximately 33% of the benefit that can be expected from RT vs no RT. Since the START trials have demonstrated that the 40âGy is non-inferior to 50âGy we can thus consider a non-inferiority margin of 3% as appropriate for this study.
        
        
          Sample size
          The sample is calculated based on the assumption that the 5-year local recurrence rate in the control arm is 5% with an exponential distribution. We hypothesize that the use of 1-week course of adjuvant radiotherapy will not increase the locoregional recurrence beyond 8% (absolute difference of 3%), corresponding to a hazard ratio of 1.63. We further assume that patients will be accrued over 5âyears with an initial ramp-up in the first year and that 2% of the patients will be lost to follow-up each year of the trial. The total trial duration is expected to be 10âyears to ensure a minimum follow-up of 5âyears for the last patient. For a fixed sample size design to achieve the required number of events to achieve a one-sided type I error of 0.025 and a power of 80% the total number of events required is 140. The total planned sample size is 2100 patients.