Feasibility of a Chemotherapy With Docetaxel-Prednisone for Castration-resistant Metastatic Prostate Cancer Elderly Patients

Inclusion Criteria: * Age \>= 75 * Histologically proven prostate adenocarcinoma * Metastatic disease, not pre-treated with chemotherapy refractory to castration * Hormone refractory prostate cancer is defined as follows: * Patients with documented testosterone castration (\<0.50 ng / ml) * Patient who received prior hormonal therapy (either orchidectomy or Luteinizing hormone-releasing hormone (LHRH) agonist alone or combined with an anti-androgen) * Patients should continue primary androgen suppression by LHRH agonist (in case of non-surgical castration) * For patients treated with anti-androgens prior to inclusion, a wash-out period is required (4 weeks for flutamide and nilutamide, 6 weeks for other products) as well as measured progression after anti-androgen discontinuation. * Progressive disease under hormonotherapy, with progression defined by Increase of PSA level (two consecutive increases of PSA compared to baseline with a minimum of one week between both measurements) OR emergence of a new lesion OR measurable progressive disease (increase of a previous measurable lesion \>= 25% in cross section) OR progressive bone metastases (defined only by the appearance of a new lesion on bone scan) OR progressive symptoms (defined as cancer pain Grade 2 according to the NCI-CTC V4.0, despite level 2 analgesics intake). * Patients of Groups 2 and 3 \[ "vulnerable" and "frail"\] of SIOG classification * WHO Performance Status (PS) \>= 3 * PSA \>= 5 ng / ml * Neutrophils \>= 2.109 /L * Platelets \>= 100.109/L * Haemoglobin ≥ 9 g/dl * Bilirubin and SGOT / SGPT \<1.5 x ULN (\<= 2.5 x ULN if hepatic metastasis) * creatinine \<= 2.5 x ULN * In case of previous palliative or analgesic radiotherapy, a minimum of 14 days must have elapsed between end of radiotherapy and inclusion into the study * Previous treatment with bisphosphonates should be continued without change during the study treatment and can not be initiated either within 28 days prior to study entry or during the study * Signed informed consent by patients, according to local regulations Exclusion Criteria: * "healthy" or "terminal illness" Groups according to the recommendations of International Society of Geriatric Oncology (SIOG) * Concomitant or previous malignancy within 5 years prior the study (except basal or squamous in situ cell skin carcinoma) * Presence of brain metastasis symptoms * Prior treatment by intravenous radiopharmaceutical agent (e.g. Strontium 89, Samarium lexidronam) within 2 months before study entry * Initiation of a bisphosphonate therapy within 28 days prior to randomisation * Any concomitant anticancer treatment (radiotherapy, radiopharmaceutical agent, chemotherapy) * Patients with uncontrolled infection * Patients with peripheral neuropathy of grade\> 1 * Patients medically unstable (e.g. unstable diabetes, uncontrolled hypertension or decompensated heart failure or myocardial infarct within 3 months) * Gastro duodenal active ulcer * Hypersensitivity to study drugs * Treatment with any experimental drug within 30 days prior to or during the study * Psychological, familial, sociological or geographical location conditions which do not allow medical monitoring and compliance with study protocol. * Patients protected by the law or patients placed under protective supervision of adults