Study of First-line Single-agent Panitumumab in Frail Elderly Patients With Advanced Wild Type K-RAS Colorectal Cancer

Inclusion Criteria: * Signed Inform Consent * Age \> 70 years. * Histologically documented metastatic colorectal cancer not candidate for surgical resection * Wild type K-RAS * Measurable disease by RECIST Criteria * Intermediate or High-risk group according to the Köhne Prognostic Classification * ECOG status \< 3 * Magnesium ≥ institutional lower limit of normal * frail elderly patients and or not candidates for chemotherapy: Frail elderly patients: Presence of one or more of the following criteria: * Dependence for one of the basic daily living activities (Katz Index) * Three or more comorbid conditions according Charlson scale and dependence for one of the instrumental activities of daily living (IADL) * Presence one or more of the following geriatric syndromes (age \> 85 years, fecal or urinary incontinence in the absence of stress, frequent falls, spontaneous bone fractures, neglect) Presence of one or more of the following criteria that make patients not candidates for chemotherapy: * neutrophils \< 2000/mm3 * platelets \< 100.000/mm3 * creatinine clearance \< 30 ml/min and bilirubin levels \> 1.5 x ULN * creatinine clearance \< 30 ml/min and AST or ALT levels \> 3 x UNL (if liver metastasis \> 5 x ULN) Exclusion Criteria: * Patients will be excluded from the study if they have received prior systemic therapy for the treatment of metastatic colorectal carcinoma or antiEGFR therapy, with the exception of adjuvant fluoropyrimidine-based chemotherapy given at least…