Summary & Overview
CPT 81521: mRNA Microarray Breast Cancer Recurrence Score
CPT code 81521 denotes an mRNA microarray–based molecular diagnostic assay that analyzes 70 genes and applies an algorithm to produce a breast cancer recurrence score. This test informs prognostic assessment and can influence systemic therapy decisions, making it clinically significant across oncology care and laboratory services nationwide. Payers commonly covering or evaluating coverage for this service include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
Readers will learn what the code represents, the clinical context for use, and the national payer landscape relevant to reimbursement and coding practice. The publication provides benchmarks and comparative coverage context, summarizes policy updates affecting molecular diagnostics, and outlines coding and billing considerations for laboratories and clinicians. It also highlights typical sites of service and where the procedure fits within oncology care pathways. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 81521 describes a laboratory service that performs mRNA microarray analysis of 70 genes and applies an algorithmic analysis combining the laboratory results with patient data to generate a breast cancer recurrence score. This is a molecular diagnostic test used to help characterize tumor biology and estimate risk of recurrence.
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Service type: Molecular diagnostic laboratory testing with algorithmic clinical reporting
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Typical site of service: Clinical diagnostic laboratory or reference laboratory performing high-complexity molecular testing
Clinical & Coding Specifications
Clinical Context
A 55-year-old woman with newly diagnosed, estrogen receptor–positive, node-negative invasive breast carcinoma undergoes primary surgical resection. The surgical pathology report documents a 1.8 cm invasive ductal carcinoma, grade 2, with clear margins and no nodal involvement on sentinel lymph node biopsy. The oncology team orders a tumor gene expression assay to determine a breast cancer recurrence score to inform adjuvant chemotherapy decisions. A fresh surgical specimen or formalin-fixed paraffin-embedded (FFPE) tissue block is sent to a certified molecular pathology laboratory. The laboratory technologist performs 81521 testing: mRNA microarray analysis of a 70-gene panel and algorithmic integration of the gene expression results with clinical variables to generate a recurrence score. The lab issues a report to the ordering medical oncologist and documents specimen accessioning, assay controls, analytic validity, and the computed recurrence score in the permanent record. Typical sites of service include an independent molecular diagnostic laboratory, hospital-based pathology lab, or a reference commercial laboratory. Typical billing uses the professional and technical component considerations depending on whether the lab performs the full test (81521 without a split) or only the technical component (TC) when applicable.
Coding Specifications
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