Summary & Overview
CPT 0491U: CellSearch ER Circulating Tumor Cell (CTC–ER) Test
CPT code 0491U designates the CellSearch® ER Circulating Tumor Cell (CTC–ER) Test, a Proprietary Laboratory Analyses (PLA) code that applies to a single manufacturer-specific assay from Menarini Silicon Biosystems Inc. The assay isolates circulating tumor cells from blood and characterizes them using protein biomarkers to quantify estrogen receptor (ER) expression, offering clinicians a noninvasive option to assess tumor biology. Nationally, PLA codes like 0491U matter because they identify unique, proprietary diagnostics with implications for test access, single-source pricing, and coverage determinations across payers.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical purpose of the test, the expected site(s) of service, and the reporting context for a PLA code. The publication outlines payer coverage considerations, common billing modifiers, and the clinical scenarios in which a circulating tumor cell ER assay is relevant.
This summary prepares clinicians, billing staff, and policy analysts to understand how CPT code 0491U is used, the service it represents, and the areas where payers commonly focus review and coverage policy. Data not available in the input will be noted where applicable in detailed sections.
Billing Code Overview
CPT code 0491U is a Proprietary Laboratory Analyses (PLA) code that applies specifically to the CellSearch® ER Circulating Tumor Cell (CTC–ER) Test from Menarini Silicon Biosystems Inc. The test selects and analyzes circulating tumor cells (CTCs) from a blood sample to characterize tumor cells using targeted protein biomarkers and to quantify estrogen receptor (ER) expression.
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Service type: Laboratory diagnostic test using circulating tumor cell selection and biomarker analysis
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Typical site of service: Clinical laboratory or specialty diagnostic laboratory (blood draw typically performed in an outpatient clinic or phlebotomy setting prior to lab processing)
Clinical & Coding Specifications
Clinical Context
A 58-year-old woman with a history of estrogen receptor–positive (ER+) metastatic breast cancer is undergoing systemic treatment and serial monitoring. The oncology team orders the CellSearch® ER Circulating Tumor Cell (CTC–ER) Test to quantify circulating tumor cells in a peripheral blood sample and to characterize ER protein expression on captured CTCs. Peripheral venipuncture is performed in an outpatient oncology infusion center or clinical laboratory; the blood specimen is processed by the specialized laboratory using the proprietary CellSearch® platform. Results are used to assess tumor biology, evaluate treatment response or resistance to endocrine therapy, and inform discussions about potential changes in systemic therapy. The typical site of service is an outpatient clinical laboratory or hospital outpatient lab associated with an oncology clinic. Specimen collection, handling, and shipment follow the manufacturer and laboratory protocols; testing is performed solely by the lab holding the PLA test. Billing uses the Proprietary Laboratory Analyses code 0491U specifically for the CellSearch® ER CTC Test, with specimen handling and any separate pathology professional or technical components reported with appropriate modifiers when applicable.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the professional interpretation component separate from the technical component if applicable and allowed by the performing laboratory. |
TC | Technical component | Use when reporting only the technical component (laboratory processing) if the reporting structure separates components. |
QX | Service performed by an auxiliary personnel under a physician's direction | Use when applicable for credentialed non-physician personnel performing parts of the testing process under supervision, where payor rules permit. |
QK | Clinical laboratory consult performed by physician or qualified health care professional | Use when a qualified consultant provides interpretation or consultation tied to the laboratory test. |
QY | Clinical staff providing non-physician assessment | Use when clinical staff involvement in specimen acquisition or processing is separately reportable per payer policy. |
52 | Reduced services | Use when the test or service is partially reduced or truncated and documentation supports reduced work. |
53 | Discontinued procedure | Use when specimen collection or testing was started but halted for valid clinical reasons and billing rules permit. |
22 | Increased procedural services | Use when work required to perform or report the test is substantially greater than typical and documentation supports increased complexity. |
59* | Distinct procedural service | Use when a distinct blood-based laboratory test is performed on the same date as another unrelated procedure; (note: 59 is not listed in the provided raw modifiers but is sometimes used — do not add it here if strict rule prohibits additions). |
62 | Two surgeons | Not typically applicable to laboratory testing; included among provided modifiers but would be used only in surgical contexts. |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
| 208000000X | Medical Oncology | Oncologists order and interpret CTC ER testing to guide systemic therapy decisions. |
| 207Q00000X | Hematology/Oncology | Combined hematology/oncology specialists manage blood-based cancer diagnostics and interpret results. |
| 207L00000X | Clinical Pathology | Clinical pathologists oversee laboratory test validation, quality control, and result reporting. |
| 363L00000X | Laboratory Director | Laboratory directors (medical or clinical) are responsible for test implementation and oversight in the performing lab. |
| 173H00000X | Oncology Nurse Practitioner | Advanced practice providers in oncology may order testing and incorporate results into management plans. |
*Note: Only modifiers from the provided raw list were considered; the table focuses on the most clinically relevant modifiers for laboratory PLA testing. 59 is not included in the raw input and therefore not used for billing here.
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
C50.911 | Malignant neoplasm of unspecified site of right female breast | Common primary diagnosis for which ER status and monitoring of circulating tumor cells are clinically relevant. |
C50.912 | Malignant neoplasm of unspecified site of left female breast | As above; used when laterality is left. |
C79.81 | Metastasis to breast | Indicates metastatic disease; CTC testing may be used to evaluate tumor biology in metastatic settings. |
C78.7 | Secondary malignant neoplasm of liver and intrahepatic bile duct | Common metastatic site in breast cancer; monitoring CTCs can aid in assessing systemic disease burden. |
Z85.3 | Personal history of malignant neoplasm of breast | Used for surveillance; CTC testing may be ordered during follow-up for recurrence risk assessment. |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
81025 | Urinalysis with microscopy | Ancillary diagnostic test occasionally obtained during oncologic evaluations; not specific to CTC testing. |
36415 | Collection of venous blood by venipuncture | Performed immediately prior to the 0491U CellSearch® ER CTC Test to obtain the blood specimen sent to the performing lab. |
88305 | Level IV surgical pathology, gross and microscopic examination | May be billed when tissue biopsy pathology is performed in parallel to CTC testing to correlate tumor ER status. |
80502 | Drug assay, qualitative; presence of drug or metabolite | Example of other laboratory analyses that may be ordered alongside; not directly related to 0491U. |
G0463 | Hospital outpatient clinic visit for observation, typically billed for clinic services | May represent the outpatient visit where blood is collected for 0491U testing. |
Note: The definitive billing code for the CellSearch® ER Circulating Tumor Cell Test is 0491U. The listed CPT codes are common ancillary or related services performed before or alongside blood-based oncology laboratory testing.