TL;DR: The Centers for Medicare & Medicaid Services modified NCD 134 governing CA 15-3 and CA 27.29 tumor antigen testing, effective March 7, 2026. Here's what billing teams need to know before submitting claims.
CMS CA 15-3 and CA 27.29 coverage policy under NCD 134 has been updated. This policy sits under the Diagnostic Laboratory Tests benefit category and directly affects labs and oncology practices billing for breast cancer monitoring. The policy does not list specific CPT or HCPCS codes in the current version — but the clinical criteria governing when these tests are medically necessary are clearly defined, and getting them wrong means a claim denial.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | CMS (Centers for Medicare & Medicaid Services) |
| Policy | Tumor Antigen by Immunoassay — CA 15-3/CA 27.29 |
| Policy Code | NCD 134 (NCD 134-v1 in Medicare system) |
| Change Type | Modified |
| Effective Date | March 7, 2026 |
| Impact Level | Medium |
| Specialties Affected | Medical oncology, clinical laboratory, pathology, hematology/oncology billing |
| Key Action | Audit active breast cancer monitoring orders — confirm you're billing CA 15-3 or CA 27.29, never both on the same claim |
CMS CA 15-3 and CA 27.29 Coverage Criteria and Medical Necessity Requirements 2026
NCD 134 is the National Coverage Determination governing Medicare coverage of CA 15-3 and CA 27.29 tumor antigen immunoassay testing. These are serum-level tests that measure specific proteins and carbohydrates used as tumor markers. When elevated, these markers reflect tumor size and grade — making them useful tools for tracking breast cancer progression and treatment response.
CMS considers CA 15-3 medically necessary to aid in the management of patients with breast cancer. That language matters. "Aid in management" is not the same as "diagnose." This test does not get covered when a clinician is trying to figure out whether a patient has cancer. It gets covered when a confirmed breast cancer patient is being monitored.
CA 27.29 is treated as equivalent to CA 15-3 under this coverage policy. CMS views them as interchangeable. That equivalence has a direct billing consequence — you pick one and stick with it.
Serial testing is a requirement, not a suggestion. The policy states that CA 15-3 testing "must be used in conjunction with other clinical methods for monitoring breast cancer." A standalone order without supporting clinical documentation is a claim denial waiting to happen.
This policy does not reference prior authorization requirements at the NCD level. However, your Medicare Administrative Contractor may have additional local coverage determination (LCD) rules that apply. If your MAC has a relevant LCD, that LCD governs in addition to this NCD. Check your MAC's website before the effective date of March 7, 2026.
CMS CA 15-3 and CA 27.29 Exclusions and Non-Covered Indications
The most important exclusion in NCD 134 is clear: these tests are not covered for evaluating patients with signs or symptoms suggestive of malignancy. That means you cannot use CA 15-3 or CA 27.29 as a diagnostic workup tool. CMS drew a hard line here — this is a monitoring test, not a diagnostic test.
The real issue is where clinical documentation blurs this line. If the ordering physician's notes describe a patient presenting with new symptoms being evaluated for possible recurrence, the claim may look like a diagnostic workup rather than monitoring. Your documentation needs to establish that the patient has an active or prior breast cancer diagnosis and that this test is part of ongoing management.
The other exclusion to internalize: billing both CA 15-3 and CA 27.29 for the same patient. CMS explicitly says to use one consistently, not both. Billing both is not just a coverage issue — it signals a documentation problem and puts you at audit risk.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| Monitoring breast cancer treatment response (CA 15-3, serial testing) | Covered | Policy does not list specific codes | Must be used with other clinical methods; not as standalone |
| Monitoring breast cancer treatment response (CA 27.29, serial testing) | Covered | Policy does not list specific codes | Equivalent to CA 15-3; use one or the other, not both |
| Assessing presence of recurrent disease post-surgical therapy | Covered | Policy does not list specific codes | Must support with clinical documentation of prior diagnosis |
| Diagnostic workup for signs or symptoms suggestive of malignancy | Not Covered | Policy does not list specific codes | Explicitly excluded — this is a monitoring test only |
| Concurrent billing of CA 15-3 and CA 27.29 for same patient | Not Covered | Policy does not list specific codes | CMS treats these as equivalent; bill one, not both |
CMS Tumor Antigen Billing Guidelines and Action Items 2026
NCD 134 CA 15-3 and CA 27.29 billing is not complicated in concept — but it breaks down fast when documentation doesn't match the claim. Here's what your team needs to do before March 7, 2026.
| # | Action Item |
|---|---|
| 1 | Audit your active breast cancer monitoring orders now. Pull every standing order for CA 15-3 and CA 27.29 in your system. Identify any patient where both tests are ordered. Flag those accounts for physician review before the effective date. Billing both on the same claim will get denied. |
| 2 | Standardize to one marker per patient. Work with your medical director or ordering physicians to select either CA 15-3 or CA 27.29 for each breast cancer patient in monitoring. Document that selection in the chart. CMS says pick one and use it consistently — make that a workflow rule, not a case-by-case decision. |
| 3 | Tighten your documentation requirements for serial testing. CA 15-3 and CA 27.29 billing requires the test to be used in conjunction with other clinical methods. Your documentation should reflect the full monitoring picture — not just a lab order. If the chart only shows a lab order with no supporting clinical notes, you're exposed. |
| 4 | Train your front-end staff on the diagnostic vs. monitoring distinction. This is where most claim denials originate. If an order comes in for CA 15-3 on a patient being evaluated for suspected malignancy, that's a non-covered indication under NCD 134. Your billing team needs to know the difference before the claim goes out, not after the denial comes back. |
| 5 | Check your MAC's local coverage determination. NCD 134 sets the national floor, but your Medicare Administrative Contractor may have additional requirements. Some MACs specify frequency limitations or require specific ICD-10 diagnosis codes to support medical necessity. If your MAC has an LCD that crosses with NCD 134, the LCD adds requirements on top of the NCD — it doesn't replace them. |
| 6 | Review your charge capture setup for this category. The policy does not list specific CPT or HCPCS codes. Confirm with your lab or billing vendor which codes your system maps to CA 15-3 and CA 27.29 testing. Mismatched charge capture is a silent revenue leak — the test gets ordered, the wrong code gets billed, and reimbursement either fails or goes to audit. |
| 7 | If you're uncertain how this applies to your patient mix, loop in your compliance officer. The diagnostic vs. monitoring boundary can get murky in real clinical workflows, especially for patients transitioning from active treatment to surveillance. Get a second set of eyes before the effective date. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Tumor Antigen Immunoassay Under NCD 134
The policy as published in NCD 134-v1 does not include specific CPT, HCPCS, or ICD-10 codes. CMS has not listed procedure codes directly in this version of the policy.
For procedure code lookup, CMS directs billers to the quarterly Covered Code Lists published alongside this policy. Check the CMS website for the most current version of those lists. You can also reference Chapter 120 of the Medicare Claims Processing Manual (Clinical Laboratory Services Based on Negotiated Rulemaking) for CA 15-3 and CA 27.29 tumor antigen billing instructions.
What to Do Without Published Codes
This is a known frustration with some NCDs. The policy governs coverage criteria clearly but defers code-level detail to supplemental documents. Your action here is practical:
- Contact your MAC directly and ask which CPT codes they accept for CA 15-3 and CA 27.29 immunoassay claims under NCD 134
- Verify your lab's current charge capture maps to codes that align with the Covered Code Lists
- Do not assume the codes you're currently billing are correct without checking against the published quarterly list
The absence of codes in the NCD itself does not mean this is a low-stakes policy. The medical necessity rules are explicit. A denial based on wrong code selection or missing documentation is just as painful as one based on a coverage exclusion.
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