Here is the design of a clinical trial:

Official Title: Evaluation of the Incidence and Prevalence of Sarcopenia in Patients 70 Year and Older With Localized and Locally Advanced Porstate Cancer, Treated by Radiotherapy and Androgen Deprivation Therapy. a Monocentric Cohort Trial

Included conditions:
- Prostate Cancer

Study Armgroups:

Interventions:
- {'type': 'OTHER', 'name': 'Prevalence of sarcopenia in older patient with prostate cancer', 'description': 'All patients are screened for sarcopenia with the SAR-F questionnaire test score ≥4/10 suspected of sarcopenia will undergo a dual-X-ray exam to dertemine their skeletal muscle mass and the prevalence of sarcopenia before oncological treatment.'}

Primary Outcomes:
- {'measure': 'Prevalence of sarcopenia in older patient with prostate cancer', 'description': 'All patients are screened for sarcopenia with the SAR-F questionnaire test', 'timeFrame': '36 months'}

Please estimate the sample size based on the assumption: 
Two-sided 95% confidence interval with a width between 0.115 to 0.131.
Sample size, power, and statistical methods
          Under the assumption that the prevalence of sarcopenia in older patients with prostate cancer before initiation of treatment with ADT is between 20 to 30%, according to one of the rare studies published on the subject [21], a sample size of 200 subjects allows an estimation with a width of two-sided 95% confidence interval between 0,115 to 0.131. Previous feasibility analysis showed current collaboration between urologist, radiotherapist and geriatrician should allow enrollment of the adequate number of patients during the trial period.