RATIONALE: Studying samples of tissue in the laboratory from patients receiving carboplatin and paclitaxel with or without sorafenib tosylate may help doctors learn more about the effects of this treatment on cells. It may also help doctors understand how well patients respond to treatment.

PURPOSE: This research study is studying biomarkers in predicting response to chemotherapy in patients with advanced or metastatic melanoma previously treated with carboplatin and paclitaxel with or without sorafenib tosylate.

OBJECTIVES:

• To independently correlate the gene expression and promoter methylation profiles to chemotherapy response in patients with advanced or metastatic melanoma treated with carboplatin and paclitaxel with versus without sorafenib on clinical trial ECOG-E2603.
• To develop a predictive model of chemotherapy response utilizing integrated analysis of gene expression and promoter methylation data.
• To evaluate whether the NER pathway haplotypes are associated with platinum drug resistance and survival.

OUTLINE: This is a multicenter study.

Archived paraffin-embedded tissue samples are analyzed for gene expression and promoter methylation profiles, and genes involved in the NER pathway.

DISEASE CHARACTERISTICS:

• Diagnosis of melanoma

  • Unresectable locally advanced or stage IV disease

• Received carboplatin and paclitaxel with versus without sorafenib on clinical trial ECOG-E2603

• Archived paraffin-embedded tissue samples

  • Responder (complete or partial response, or stable disease) and non-responder (disease progression or unavailable)

PATIENT CHARACTERISTICS:

• Not specified

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics

Samples from patients enrolled on E2603 from whom samples were submitted for research