TL;DR: The Centers for Medicare & Medicaid Services modified NCD 134, the national coverage determination governing CA 15-3 and CA 27.29 tumor antigen testing by immunoassay, effective March 7, 2026. Here's what billing teams need to know.
This update to the CMS CA 15-3/CA 27.29 coverage policy tightens the rules around when these breast cancer monitoring markers are billable to Medicare. The policy does not list specific CPT or HCPCS codes in its current form — a gap your billing team needs to account for when verifying charge capture. If your lab or oncology practice bills these tumor marker assays, review your documentation protocols and ordering patterns before the effective date of March 7, 2026.
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 |
| Change Type | Modified |
| Effective Date | 2026-03-07 |
| Impact Level | Medium |
| Specialties Affected | Oncology, Clinical Laboratory, Hematology/Oncology, Breast Surgery |
| Key Action | Audit CA 15-3 and CA 27.29 orders to confirm you're billing one marker consistently per patient — not both |
CMS CA 15-3 and CA 27.29 Coverage Criteria and Medical Necessity Requirements 2026
The core of this coverage policy is straightforward: CA 15-3 and CA 27.29 are covered for monitoring breast cancer patients — not for diagnosing new or suspected malignancies.
Medical necessity under NCD 134 applies to management of patients with a confirmed breast cancer diagnosis. Serial testing must accompany other clinical methods. You can't bill these markers in isolation and call it monitoring.
Here's where billing teams trip up: CA 15-3 and CA 27.29 are clinically equivalent. CMS treats them as interchangeable. The policy says clearly — pick one and use it consistently for each patient. Billing both on the same patient is not covered.
Prior authorization is not specifically required under NCD 134 as written, but that doesn't mean you're in the clear. Medicare Administrative Contractors may impose additional local requirements on top of this national coverage determination. Check with your MAC before assuming national policy is the only layer you're working with.
The reimbursement exposure here is real. If your practice or lab has been ordering both markers for the same breast cancer patient — even in alternating cycles — those claims are at risk under this coverage policy. CMS is explicit: use one or the other, not both.
CMS CA 15-3 and CA 27.29 Exclusions and Non-Covered Indications
The single biggest exclusion in NCD 134 is also the one most likely to generate a claim denial: ordering these tests for diagnostic evaluation.
If a patient presents with signs or symptoms that suggest malignancy but does not yet have a confirmed cancer diagnosis, these assays are not covered. Period. CMS excludes CA 15-3 and CA 27.29 from the workup of suspected cancer entirely.
This is a meaningful clinical boundary. Oncologists sometimes order tumor markers as part of a diagnostic workup when a patient has a breast mass or abnormal imaging. Under this coverage policy, that's a non-covered indication. The test has to be about monitoring a known malignancy — assessing recurrent disease or the patient's response to treatment.
The policy also implies a frequency limitation worth noting. The service "may be ordered at times necessary" to assess recurrence or treatment response. That language gives payers flexibility to question claims where testing frequency looks excessive relative to treatment cycles. Document your clinical rationale for each order, not just the diagnosis code.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| Monitoring known breast cancer — response to treatment | Covered | Not listed in policy | Serial testing required; use CA 15-3 OR CA 27.29, not both |
| Monitoring known breast cancer — assessing recurrent disease | Covered | Not listed in policy | Must be used with other clinical methods |
| Diagnostic workup for signs/symptoms suggestive of malignancy | Not Covered | Not listed in policy | Exclusion is explicit; claim denial risk is high |
| Concurrent billing of both CA 15-3 and CA 27.29 for the same patient | Not Covered | Not listed in policy | CMS deems them equivalent; bill one consistently |
CMS CA 15-3 and CA 27.29 Billing Guidelines and Action Items 2026
These are the steps your billing team and lab should take before March 7, 2026.
| # | Action Item |
|---|---|
| 1 | Audit your active breast cancer patients with standing CA 15-3 or CA 27.29 orders. Identify any patient where both markers are being ordered — even if they're not running simultaneously. That billing pattern is non-covered under NCD 134 and should be corrected before the effective date. |
| 2 | Standardize your ordering templates. If your EHR has a breast cancer monitoring order set, remove the ability to order both CA 15-3 and CA 27.29 for the same patient. Pick one marker per patient and document that choice in the chart. Consistency matters for CA 15-3 and CA 27.29 billing under this policy. |
| 3 | Update your ABN workflow for diagnostic-workup scenarios. When an ordering provider wants to run CA 15-3 or CA 27.29 on a patient with signs or symptoms of suspected malignancy — but no confirmed diagnosis — issue an Advance Beneficiary Notice of Noncoverage. Medicare will not pay for this indication. Your patient needs to know before the test runs, not after the claim denies. |
| 4 | Check with your MAC for local coverage determination overlays. NCD 134 is a national policy, but your Medicare Administrative Contractor may have issued an LCD with additional billing guidelines, diagnosis code requirements, or frequency limits. Don't assume the NCD is the only rule that applies to your region. |
| 5 | Review your diagnosis code documentation. A covered CA 15-3 or CA 27.29 claim needs to link clearly to an established breast cancer diagnosis — not a rule-out, not a screening, not a "history of." Your ICD-10 coding needs to support active monitoring of a confirmed malignancy. If your coders are pulling Z-codes or symptom codes for these orders, that's a medical necessity problem waiting to become a claim denial. |
| 6 | Talk to your compliance officer if your lab processes high volumes of these markers. If CA 15-3 and CA 27.29 testing represents significant revenue at your facility, the overlap between diagnostic and monitoring indications is worth a formal audit before March 7, 2026. The line between "monitoring for recurrence" and "evaluating new signs and symptoms" can blur in practice — and CMS draws it sharply here. |
| 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
Covered CPT Codes (When Selection Criteria Are Met)
The policy data for NCD 134 does not list specific CPT or HCPCS codes. CMS references the Medicare Claims Processing Manual, Chapter 120, Clinical Laboratory Services Based on Negotiated Rulemaking, for claims processing instructions. Check that chapter and your MAC's quarterly Covered Code Lists — which CMS links from the NCD itself — for the current applicable codes.
Your billing team should not guess at codes here. Pull the quarterly Covered Code Lists directly from the CMS source before billing CA 15-3 and CA 27.29 immunoassay services under NCD 134.
A Note on Code Lookup
The absence of codes in this policy document is itself a signal. CMS maintains separate Covered Code Lists updated quarterly — the NCD points there deliberately. If your team has been billing these assays without verifying against the current quarterly list, that's a gap in your process worth fixing now.
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