Study of Tissue and Blood Samples From Patients With Recurrent Prostate Cancer Who Received Lapatinib on Clinical Trial ECOG-E5803

RATIONALE: Studying samples of tumor tissue and blood in the laboratory from patients with cancer may help doctors learn more about changes that occur in DNA and identify biomarkers related to cancer. It may also help doctors predict how patients will respond to treatment. PURPOSE: This research study is looking at tissue and blood samples from patients with recurrent prostate cancer who received lapatinib on clinical trial ECOG-E5803.

OBJECTIVES: * To determine the association between polymorphisms in drug metabolizing enzymes and lapatinib ditosylate-associated toxicity in patients with hormone-sensitive recurrent prostate cancer receiving lapatinib ditosylate on clinical trial ECOG-E5803. * To determine the association between mutations in EGFR, HER-2 and Kras; protein expression of HER2, EGFR, MAPK and AKT; polymorphism controlling androgen synthesis; and progression-free survival. OUTLINE: Tissue and blood samples collected from patients enrolled on clinical trial ECOG-E5803 are analyzed for correlative studies. Samples are assessed for HER2, EGFR, MAPK, and Akt; EGFR mutations and polymorphisms in CYP3A4; Ras mutations; recently identified mutations in HER2-neu and Kras; and additional polymorphisms in the lapatinib ditosylate metabolic pathway by automated quantitative IHC. Predictors of efficacy and toxicity are analyzed, including markers in the EGFR pathway as predictors of progression-free survival.