Doxorubicin vs. Trabectedin Plus Doxorubicin in Non Operable and/or Metastatic STS

Inclusion Criteria: * The patient must sign voluntarily the informed consent from before any study test is conducted that is not part of routine patient care, with the knowledge that he/she can abandon the study at any time without this affecting his/her previous care. * Aged between 18 and 70. * Pathological diagnosis of non operable and/or metastatic soft tissue sarcoma. * The following histological subtypes can be included: * Undifferentiated pleomorphic sarcoma (previously,malignant fibrous istiocytoma) * Leiomyosarcoma * Angiosarcoma * Liposarcoma * Synovial sarcoma * Fibrosarcoma * Hemangiopericytoma * Neurofibrosarcoma * Mixofibrosarcoma * Unclassified sarcoma * Measurable disease, according to RECIST criteria * Performance status 0-2 Eastern Cooperative Oncology Group(ECOG). * Adequate bone marrow function (hemoglobin \> 10 g/dL, leukocytes ≥ 3.000/mm3, neutrophils ≥1.500/mm3, platelets ≥ 100.000/mm3). Patients with plasma creatinine ≤ 1,6 mg/dL, transaminases ≤2.5 times the upper limit of normal (ULN), total bilirubin ≤ upper limit of normal (ULN), CPK ≤ 2.5 times upper limit of normal (ULN), alkaline phosphatase ≤ 2.5 times the upper limit of normal (ULN) are acceptable. If the increase of alkaline phosphatase is \> 2.5 times the upper limit of normal (ULN), then the alkaline phosphatase liver fraction and/or 5' nucleotidase and/or GGT must be ≤ upper limit of normal (ULN). * Men or women of child bearing potential should be using an effective method of contraception before entry into the study and throughout the same and for 6 months after ending the study. Women of childbearing potential must have a negative urine pregnancy test before study entry. * Normal cardiac function with a Left ventricular ejection fraction (LVEF) ≥ 50% by echocardiogram or Multiple Uptake Gated Acquisition Scan (MUGA). Exclusion Criteria: * Previous chemotherapy treatment. * Previous radiotherapy involving the only localization(s) of measurable tumoral disease. * Performance status\> 2 Eastern Cooperative Oncology Group(ECOG). * Central Nervous System (CNS) metastases. * Plasma bilirubin \> upper limit of normal(ULN). * Creatinine \> 1.6 mg/dL. * History of other neoplastic disease with the exception of basalioma or in situ cervical cancer adequately treated. * Significant cardiovascular disease (for example, dyspnea \> 2 NYHA) * Significant systemic diseases grade 3 or higher on the NCI-CTC version 3.0 scale, that limit patient availability, or according to investigator judgment may contribute significantly to treatment toxicity. * Uncontrolled bacterial, mycotic or viral infections. * Women who are pregnant or breast-feeding * Psychological, familial, social or geographic circumstances that limit the patient's ability to comply with the protocol or informed consent. * Patients participating in another clinical trial or receiving any other investigational product. * Patients who had participated in another clinical trial and/or had received any other investigational product in the last 30 days prior to inclusion. * The following histologic subtypes are excluded: * Rhabdomyosarcoma * Ewing's family of tumors * Desmoplastic small round cell tumor * Clear cell sarcoma * Alveolar sarcoma