Here is the design of a clinical trial:

Official Title: The Effect of Perceived Injustice Targeted Pain Neuroscience Education and Motivational Interviewing Compared to Biomedical Focused Education in Breast Cancer Survivors

Included conditions:
- Breast Neoplasms
- Survivorship
- Pain, Chronic

Study Armgroups:
- {'label': 'Pain Neuroscience Education (PNE) + Motivational Interviewing (MI)', 'type': 'EXPERIMENTAL', 'description': "Breast cancer survivors assigned to the experimental intervention will participate in 1 online PNE session followed by 3 PNE + MI sessions spread over 4 weeks. Each session will last for approximately 45 minutes and all sessions will be held in one-on-one format, allowing to individually tailor content to the patient's maladaptive beliefs and perceived injustice. After the first live session, breast cancer survivors will receive a perceived injustice-targeted PNE information leaflet that they need to read carefully at home.", 'interventionNames': ['Behavioral: Pain Neuroscience Education (PNE)', 'Behavioral: Motivational Interviewing (MI)']}
- {'label': 'Biomedically-focused Education', 'type': 'ACTIVE_COMPARATOR', 'description': "Breast cancer survivors assigned to the experimental intervention will participate in 1 online biomedically-focused education session followed by 3 biomedically-focused education sessions spread over 4 weeks. Each session will last for approximately 45 minutes and all sessions will be held in one-on-one format in order to balance nonspecific treatment effects between treatment arms, the duration, format and number of sessions as well as the didactical approach will be identical in both treatment groups. After the first live session, breast cancer survivors will receive an information leaflet from 'Kom op tegen Kanker' regarding 'Pain in and after treatment' that they need to read carefully at home.", 'interventionNames': ['Behavioral: Biomedically-focused education']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Pain Neuroscience Education (PNE)', 'description': 'PNE is a cognitive behavioural intervention, including educating patients that pain is an output product of the brain resulting from input from multiple central and peripheral nervous system processes and leading to threat perception. Transferring that knowledge to patients, allows them to understand, accept and effectively cope with their pain. In order to obtain the targeted behavioural change, motivational interviewing is used as the communication process throughout PNE.', 'armGroupLabels': ['Pain Neuroscience Education (PNE) + Motivational Interviewing (MI)']}
- {'type': 'BEHAVIORAL', 'name': 'Motivational Interviewing (MI)', 'description': 'Motivational interviewing is a directive, collaborative, patient-centered communication approach for eliciting and enhancing motivation for behaviour change by helping clients to resolve ambivalence and uncertainty.', 'armGroupLabels': ['Pain Neuroscience Education (PNE) + Motivational Interviewing (MI)']}
- {'type': 'BEHAVIORAL', 'name': 'Biomedically-focused education', 'description': "The traditional biomedical-focused education programme explains patient's pain experience from a tissue (injured versus healthy tissue) and biomechanical perspective.", 'armGroupLabels': ['Biomedically-focused Education']}

Primary Outcomes:
- {'measure': 'Pain Outcome', 'description': "The Brief Pain Inventory is a 14-item questionnaire assessing worst pain, pain severity, and pain interference in cancer patients over the past week, reported on a scale of 0 to 10. Pain interference is measured as the average of the 7 interference items, such as walking, mood, and sleep. The Brief Pain Inventory is the most common, reliable and valid outcome measure to assess pain in cancer survivors (Cronbach's alfa and test-retest reliability score \\> 0.80).", 'timeFrame': 'T0: within the week before the randomisation and the start of the intervention'}
- {'measure': 'Pain Outcome', 'description': "The Brief Pain Inventory is a 14-item questionnaire assessing worst pain, pain severity, and pain interference in cancer patients over the past week, reported on a scale of 0 to 10. Pain interference is measured as the average of the 7 interference items, such as walking, mood, and sleep. The Brief Pain Inventory is the most common, reliable and valid outcome measure to assess pain in cancer survivors (Cronbach's alfa and test-retest reliability score \\> 0.80).", 'timeFrame': 'T1: immediately after completing intervention'}
- {'measure': 'Pain Outcome', 'description': "The Brief Pain Inventory is a 14-item questionnaire assessing worst pain, pain severity, and pain interference in cancer patients over the past week, reported on a scale of 0 to 10. Pain interference is measured as the average of the 7 interference items, such as walking, mood, and sleep. The Brief Pain Inventory is the most common, reliable and valid outcome measure to assess pain in cancer survivors (Cronbach's alfa and test-retest reliability score \\> 0.80).", 'timeFrame': 'T2: 6 months after therapy completion'}
- {'measure': 'Pain Outcome', 'description': "The Brief Pain Inventory is a 14-item questionnaire assessing worst pain, pain severity, and pain interference in cancer patients over the past week, reported on a scale of 0 to 10. Pain interference is measured as the average of the 7 interference items, such as walking, mood, and sleep. The Brief Pain Inventory is the most common, reliable and valid outcome measure to assess pain in cancer survivors (Cronbach's alfa and test-retest reliability score \\> 0.80).", 'timeFrame': 'T3: 12 months after therapy completion'}
- {'measure': 'Pain Outcome', 'description': "The Brief Pain Inventory is a 14-item questionnaire assessing worst pain, pain severity, and pain interference in cancer patients over the past week, reported on a scale of 0 to 10. Pain interference is measured as the average of the 7 interference items, such as walking, mood, and sleep. The Brief Pain Inventory is the most common, reliable and valid outcome measure to assess pain in cancer survivors (Cronbach's alfa and test-retest reliability score \\> 0.80).", 'timeFrame': 'T4: 24 months after therapy completion'}

Please estimate the sample size based on the assumption: 
The type I error was set to 0.05 and the type II error to 0.2. A risk of loss to follow-up of 20% was also considered.
Sample size calculation
          Sample size calculations were performed with G*Power 3.1.3 for between-group differences (t test) at 12 months of follow-up. The sample size calculation was based on an earlier trial regarding a conservative intervention for treating pain in BCS that had the same primary outcome (eg, BPI) and identical 12-month follow-up.46 Based on that earlier trial46 and calculation methods described by Lakens,82 the effect size was set to 0.44, based on an observed difference of 1.8 on BPI and a CI between 0.9 and 2.6 for 83 participants. The type I error was set to 0.05 and the type II error to 0.2. The resulting sample size for a one-sided test was 65 per treatment arm. Accounting for a risk of loss to follow-up of 20%, a total sample size of 156 participants is needed.