Study in Patients With Unresectable And Metastatic Melanoma: The Optimize Study

Inclusion Criteria: Prospective cohort patients: * Diagnosis date must occur on or after March 24, 2011 (date of ipilimumab approval in US) * Diagnosis of stage III (unresectable) or stage IV melanoma (includes mucosal, uveal acral-lentiginous, leptomeningeal disease) * Age ≥ 18 years at time of entry into study * Patients must be actively receiving or scheduled to receive systemic treatment (any line, eg, first, second, third line \[including investigational drugs\]). * For patients initiating new treatment, treatment must be started within 28 days after signing informed consent. * For patients currently receiving treatment, patients must enroll within the first 21 days of starting new treatment Retrospective cohort patients: * Patients with diagnosis of confirmed unresectable stage III or stage IV melanoma (including mucosal, uveal, acral-lentiginous, leptomeningeal disease) * Age ≥ 18 years at time of unresectable or metastatic melanoma diagnosis * Initiated therapy for unresectable or metastatic melanoma within 4 years prior to approval of ipilimumab (first immune checkpoint inhibitor therapy approved in US) * March 25, 2007 - March 24, 2011 * One year of follow-up data is required from date of therapy initiation, if a patient passed away within the one year of follow-up; such patients are still eligible and the date of death will be collected. 1. If retrospective patients have at least one year of follow-up data and are then treated with immuno-oncology, immune checkpoint inhibitor therapy, or targeted therapy, these patients will be analyzed separately. Exclusion Criteria: Prospective patients: * Patients participating in a clinical study that does not allow enrollment into a non interventional study or clinical studies in which the investigational treatment is blinded * Patients who started new treatment \> 21 days * Patients who enrolled in study but did not initiate treatment before 28 days * Patients with current malignancies (except non-melanoma skin cancer and the following in situ cancers: bladder, gastric, colon, endometrial, cervical/dysplasia, melanoma, or breast) that requires additional systemic therapy