Summary & Overview

CPT 81540: Molecular Tumor Profiling by RT-PCR and Algorithmic Analysis

CPT code 81540 designates a molecular diagnostic service that combines technical RT–PCR testing of 92 genes on tumor tissue with an algorithmic analysis to predict a tumor’s main cancer type and subtype. This code captures both the laboratory analytic component and the computational interpretation that yields a probabilistic cancer-type report, making it relevant for precision oncology workups and cases where tissue-based molecular classification informs diagnostic clarity.

Key national payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of what CPT code 81540 represents, why it matters for laboratory and oncology providers, and the typical clinical and laboratory contexts in which it is used.

The publication summarizes expected benchmarks and adoption considerations, clarifies clinical context for ordering and reporting such tests, and highlights where policy updates and payer coverage practices can influence access to algorithm-driven tumor profiling. The content is intended as a national-level reference for health plan administrators, laboratory directors, and oncology practice managers seeking a clear description of the service and the key issues surrounding reimbursement and clinical utility.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareCPT 81540molecular diagnosticstumor profilingRT-PCRalgorithmic interpretationprecision oncologylaboratory servicespathology

Billing Code Overview

CPT code 81540 describes a laboratory service in which a lab analyst performs technical real-time reverse transcription–polymerase chain reaction (RT–PCR) testing for 92 genes on tumor tissue and then applies an algorithmic analysis combining the assay results with patient data to report a probability of predicted main cancer type and subtype.

Service type: Molecular diagnostic tumor profiling with algorithmic interpretation.

Typical site of service: Clinical molecular laboratory or reference laboratory using tumor tissue specimens.

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A 62-year-old patient presents with a biopsy-proven metastatic carcinoma of unknown primary site. The oncology team orders molecular testing to help identify the most likely tumor origin and subtype to guide systemic therapy selection. A formalin-fixed paraffin-embedded (FFPE) tumor tissue block is sent from the hospital pathology laboratory to a reference molecular diagnostics laboratory. The lab analyst performs 81540, which uses real-time reverse transcription–polymerase chain reaction (RT–PCR) across a 92-gene panel on the tumor sample and runs an algorithmic analysis incorporating the gene expression results with available clinical data to report a probability of predicted primary cancer type and subtype. The report is delivered to the ordering oncologist and surgical pathologist and becomes part of the medical record to inform treatment planning, potential biomarker testing, and multidisciplinary tumor board discussion.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When billing separately for interpretation/analysis by a pathologist or laboratory professional distinct from the technical testing.
`TC`	Technical component	When billing only the technical component (laboratory processing and testing) and the professional interpretation is billed by another entity.
`90`	Reference (outside) laboratory	When the service was performed by an outside/reference laboratory and billing needs to indicate that arrangement.
`91`	Repeat clinical diagnostic lab test (Note: not in provided list)	Data not available in the input.
`52`	Reduced services	When a reduced or partial test is performed compared with standard procedure (e.g., insufficient tissue leads to limited panel).
`53`	Discontinued procedure	When testing is started but discontinued due to preanalytic failure (e.g., inadequate sample or assay failure).
`59`	Distinct procedural service (Note: not in provided list)	Data not available in the input.
`90`	Duplicate entry — already listed above	When indicating services performed by an outside lab (see above).
`QX`	Modifier for certified lab personnel services (CLIA requirements)	When services are performed by a qualified laboratory technician under CLIA; used with certain lab test billing in payer-specific programs.
`QK`	Medical direction of two or more technicians/technologists	When a physician directs multiple laboratory staff performing the technical aspects of testing.
`QY`	Medical direction by a physician of one technician/technologist	When a physician directly supervises a single technologist for the assay.
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services	Rarely used for laboratory assay reporting; include only if those clinicians are billing for professional component services under payer rules.
`62`	Two surgeons (Note: rarely applicable)	Not typically applicable for lab-based molecular assay; included only when surgical co-management impacts coding.

Taxonomy Code	Specialty	Notes
207RH0000X	Hematopathology	Pathologists who order, interpret, or oversee molecular tumor testing.
207RC0000X	Anatomic and Clinical Pathology	Pathologists directing molecular diagnostic laboratories and finalizing reports.
208000000X	Medical Oncology	Oncologists ordering the assay to guide systemic therapy selection.
208D00000X	Surgical Oncology	Surgeons involved in initial biopsy or resection planning and use results for operative decisions.
363L00000X	Clinical Laboratory (Molecular Diagnostics)	Laboratory specialty performing the RT–PCR assay and algorithmic analysis.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`C77.9`	Secondary malignant neoplasm of lymph node, unspecified	Metastatic disease with unknown primary where a tissue sample is used for tumor-origin prediction via `81540`.
`C80.1`	Malignant (primary) neoplasm, unspecified	Used when a confirmed malignancy lacks an identified primary site; `81540` aids classification.
`C78.7`	Secondary malignant neoplasm of liver, unspecified	Common metastatic site where biopsy specimens may be tested with `81540` to determine likely primary tumor.
`C79.31`	Secondary malignant neoplasm of brain	Metastatic brain lesions frequently require molecular origin testing to guide systemic therapy; `81540` can assist.
`C79.9`	Secondary malignant neoplasm of unspecified site	Broad code for metastasis when primary is unknown; gene expression profiling helps narrow differential.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`88305`	Level IV surgical pathology, gross and microscopic examination	Performed by the pathology laboratory to evaluate the tumor specimen and select tissue for molecular testing prior to `81540`.
`88342`	Immunohistochemistry, per single antibody stain	Often performed before or alongside gene expression testing to evaluate lineage-specific markers that complement `81540` results.
`81445`	Oncology (cancer) gene panel (5-50 genes) by sequencing	Other molecular tests that may be ordered in parallel for mutation profiling and targeted therapy selection; complements the expression-based classification of `81540`.
`81479`	Unlisted molecular pathology procedure	Used when a specific molecular analysis related to tumor classification is performed that does not have an assigned CPT code; may accompany `81540` workflow.
`0002U`	Proprietary molecular test (example)	Proprietary or newer genomic classifier tests that might be ordered as alternatives or adjuncts to `81540` in diagnostic workup.