Here is the design of a clinical trial:

Official Title: Repetitive Electrostatic Pressurised Intraperitoneal Aerosol Chemotherapy With Oxaliplatin (ePIPAC-OX) as a Palliative Monotherapy for Isolated Unresectable Colorectal Peritoneal Metastases: Protocol of a Multicentre, Open-label, Single-arm, Phase II Study (CRC-PIPAC)

Included conditions:
- Colorectal Neoplasms
- Peritoneal Neoplasms
- Appendiceal Neoplasms
- Peritoneal Carcinomatosis

Study Armgroups:
- {'label': 'repetitive ePIPAC-OX', 'type': 'EXPERIMENTAL', 'interventionNames': ['Combination Product: repetitive ePIPAC-OX']}

Interventions:
- {'type': 'COMBINATION_PRODUCT', 'name': 'repetitive ePIPAC-OX', 'description': 'Instead of standard palliative treatment, enrolled patients receive laparoscopy-controlled electrostatic pressurised intraperitoneal aerosol chemotherapy with oxaliplatin (ePIPAC-OX) (92 mg/m2 body-surface area \\[BSA\\]) with intravenous leucovorin (20 mg/m2 BSA) and bolus 5-fluorouracil (400 mg/m2 BSA) every six weeks. Four weeks after each procedure, patients undergo clinical, radiological, and biochemical evaluation. ePIPAC-OX is repeated until clinical, radiological, or macroscopic disease progression, after which standard palliative treatment is (re)considered.', 'armGroupLabels': ['repetitive ePIPAC-OX']}

Primary Outcomes:
- {'measure': 'Major toxicity', 'description': 'Number of patients with Common Terminology Criteria for Adverse Events (CTCAE) v4.0 grade III-V, up to 4 weeks after the last ePIPAC-OX', 'timeFrame': 'Expected (in case of three ePIPAC-OX): 16 weeks'}

Please estimate the sample size based on the assumption: 
The expected mean number of procedures is three per patient. Enrolled patients who do not undergo a first ePIPAC-OX are replaced to ensure 20 patients receive at least one procedure.
Sample size
        Given the absence of evident clinical endpoints in this patient category, the investigators pragmatically determined the sample size of this exploratory study. The investigators agreed that 60 procedures are required to explore the feasibility, safety, tolerability and preliminary efficacy of repetitive ePIPAC-OX in this setting. Since the expected mean number of procedures is three per patient,36 the initial sample size is determined at 20 patients. This pragmatically determined sample size is approved by the central ethics committee. Enrolled patients who do not undergo a first ePIPAC-OX (eg, systemic metastases on baseline radiology, non-access, resectable disease) are replaced to enrol 20 patients who receive at least one ePIPAC-OX.