Cancer Genetic Testing Denied by Insurance: How to Appeal

Genetic testing has become one of the most clinically important tools in modern oncology. BRCA1/2 testing guides decisions about PARP inhibitors and preventive surgery. Lynch syndrome testing identifies patients eligible for immune checkpoint immunotherapy and at risk for multiple cancers. Comprehensive tumor profiling by platforms like FoundationOne CDx and Guardant360 identifies actionable mutations that guide targeted therapy selection. Despite this clinical importance and despite FDA approvals and ACA coverage mandates, insurance denials for cancer genetic testing remain extremely common. This guide explains how to fight back.

Types of Cancer Genetic Testing and Why They Get Denied

BRCA1/2 Germline Testing

The ACA Section 2713 requires coverage at no cost-sharing for BRCA1/2 genetic testing when USPSTF criteria are met — specifically for women who have not had cancer but have a personal or family history suggesting increased risk (USPSTF A recommendation). For women who already have a cancer diagnosis (breast, ovarian, pancreatic, prostate), BRCA testing is clinically essential for treatment selection and is not merely preventive. Insurers deny BRCA testing by:

• Applying the "preventive screening" mandate incorrectly to diagnostic testing (different coverage rules apply)
• Requiring genetic counseling referral before authorizing testing, causing delays
• Denying broader hereditary cancer panel tests (e.g., 20+ gene panels) when a smaller BRCA-only test could have been ordered
• Denying testing for men with breast cancer or prostate cancer, where BRCA status guides therapy and screening decisions

Lynch Syndrome / MMR Testing

Lynch syndrome is caused by germline mutations in mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2) and increases lifetime risk of colorectal, endometrial, ovarian, and other cancers significantly. Reflex MMR testing by immunohistochemistry is now recommended for all colorectal and endometrial cancers at diagnosis. Insurers deny Lynch syndrome testing by:

• Classifying reflex IHC MMR testing as "experimental" — it is not
• Denying germline confirmatory testing after an abnormal IHC result, leaving the diagnosis incomplete
• Refusing to cover genetic counseling visits required to interpret results and counsel family members

Tumor Profiling: FoundationOne CDx and FoundationOne Liquid CDx

FoundationOne CDx is an FDA-approved comprehensive genomic profiling (CGP) assay that tests for 324 genes and provides TMB and MSI status. It is an approved companion diagnostic for multiple targeted therapies. Guardant360 CDx is a liquid biopsy CGP assay (blood-based) with similar scope and FDA companion diagnostic approvals. Insurers deny these assays by:

• Calling CGP "experimental" despite FDA approvals for multiple companion diagnostic uses
• Requiring individual single-gene tests (e.g., EGFR, ALK, ROS1 separately) rather than a CGP panel, arguing the panel is "not medically necessary"
• Denying liquid biopsy (ctDNA) testing when tissue biopsy is technically possible, even when tissue is insufficient
• Denying repeat CGP testing at disease progression to identify resistance mutations

Individual Companion Diagnostic Tests

Single-gene tests — EGFR mutation analysis in lung cancer, BRAF V600E in melanoma/colorectal/NSCLC, ALK FISH, RET, ROS1, KRAS, HER2 IHC/FISH, MSI by PCR — are FDA-approved companion diagnostics tied to specific drug approvals. Denying these tests is clinically equivalent to denying the targeted therapy itself, since eligibility cannot be determined without the test. Insurers deny companion diagnostics by:

• Routing the test to an in-network lab that doesn't offer the specific validated assay
• Requiring Prior Authorization Denied: How to Appeal" class="auto-link">prior authorization for laboratory testing in ways that delay treatment
• Denying re-testing at disease progression when resistance mutation testing is clinically necessary

ACA Coverage Mandates for Preventive Genetic Testing

Under ACA Section 2713, preventive services with USPSTF A or B ratings must be covered without cost-sharing. Relevant cancer genetic testing under this mandate includes:

• BRCA1/2 testing for women with qualifying family history (without personal cancer diagnosis)
• Lynch syndrome screening as part of colorectal cancer prevention (USPSTF B recommendation for colorectal cancer screening, which includes MMR/MSI testing in guidelines)

The 2022 Supreme Court decision in Braidwood Management v. Becerra challenged the employer mandate for some preventive services, but as of 2026, ACA preventive care coverage requirements remain in force for most marketplace and group health plans.

Your Legal Rights

Companion diagnostic coverage: If a drug is FDA-approved with a companion diagnostic, the insurer cannot cover the drug while denying the test that determines eligibility. This creates a strong legal argument for companion diagnostic coverage.

External Independent Review: Complete Guide" class="auto-link">External review: Denials of FDA-approved CGP tests and companion diagnostics are among the most commonly reversed decisions in external review when the oncology reviewer understands current practice.

ACA preventive care mandate: For high-risk individuals without cancer, BRCA testing denials under the ACA preventive care mandate are legally challengeable at the federal level.

ERISA plans: Employer-sponsored plans must follow ACA requirements for preventive services for qualifying individuals.

Building Your Appeal

1. Treating oncologist's letter of medical necessity: Explaining why the specific test is required for treatment decision-making
2. FDA companion diagnostic documentation: For FoundationOne CDx, Guardant360 CDx, and single-gene tests — showing the FDA-approved drug-test pairing
3. NCCN Guidelines: Cite biomarker testing recommendations for the specific cancer type
4. ASCO or CAP laboratory guidelines: Supporting the use of the specific testing methodology
5. Documentation of family history: For BRCA preventive testing denials
6. Clinical urgency statement: If testing delay is interrupting treatment planning

Fight Back With ClaimBack

ClaimBack helps cancer patients appeal denials for BRCA testing, Lynch syndrome testing, FoundationOne, Guardant360, and other companion diagnostics. Genetic testing is the gateway to targeted therapy — and denying it is denying your right to the best available care.

Start your appeal at ClaimBack

Cancer genetic testing denials are common, frequently wrong, and highly reversible with the right appeal. Act quickly — testing delays are treatment delays.

Related Reading

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Common Reasons Insurance Claims Are Denied