RATIONALE: Finding genetic markers for thyroid cancer in a biopsy specimen may help doctors diagnose thyroid cancer.

PURPOSE: This clinical trial is studying how well genetic analysis works in diagnosing thyroid cancer in patients with thyroid nodules.

OBJECTIVES:

• Evaluate the diagnostic accuracy of biomarkers and mRNA expression analysis using fine-needle aspiration (FNA) biopsy samples from patients with thyroid nodules.
• Correlate the level of gene expression with the aggressiveness of differentiated thyroid cancer in FNA biopsy samples.

OUTLINE: Patients undergo fine-needle aspiration (FNA) biopsy as part of routine care. Additional thyroid tissue is collected during the biopsy for gene expression analysis. Patients who have already had a biopsy undergo FNA biopsy during thyroidectomy.

Tissue samples will be examined for gene expression by reverse transcriptase-polymerase chain reaction (PCR), real-time quantitative PCR, and immunohistochemistry.

PROJECTED ACCRUAL: A total of 400 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Diagnosis of a thyroid nodule that requires fine-needle aspiration biopsy or thyroidectomy to exclude a diagnosis of thyroid cancer

PATIENT CHARACTERISTICS:

• Platelet count ≥ 70,000/mm^3
• PT (INR) ≤ 14.5
• PTT ≤ 35.2
• Not pregnant

PRIOR CONCURRENT THERAPY:

• No aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) 7 days before sample procurement