An evolving tool—not a stand-alone answer
A blood test can add information, but it cannot show where a cancer is, determine its stage, or replace imaging and tissue diagnosis.
We consider blood-based testing only when it answers a defined clinical question and interpret it alongside CT, PET/CT when appropriate, pathology, and the patient's history.
Discuss whether testing may helpBefore a diagnosis: screening and lung nodules
Low-dose CT remains the foundation of lung-cancer screening. Blood biomarkers are not part of current national screening recommendations. If CT identifies an indeterminate lung nodule, selected blood-based tests that analyze proteins, antibodies, or cell-free DNA patterns may sometimes help refine risk.
These tests are adjuncts—not stand-alone screening or diagnostic tests. They do not prove cancer or replace review of CT appearance and growth. Depending on the overall risk, the next step may be interval CT, PET/CT, bronchoscopy, needle biopsy, or surgical evaluation.
After a diagnosis: molecular treatment selection
In confirmed non-small cell lung cancer, plasma circulating tumor DNA may identify a mutation or gene fusion that helps the oncology team select targeted treatment. It is most useful when tumor tissue is limited, biopsy would be unsafe, or a time-sensitive result is needed.
A negative or inconclusive blood result does not rule out an actionable alteration and may require tissue-based testing. Liquid biopsy does not replace pathology, anatomical staging, or a multidisciplinary treatment decision.
After surgery: molecular residual disease
Circulating tumor DNA tests can look for a molecular signal called minimal or molecular residual disease (MRD). These assays can provide prognostic information, but it has not yet been proven that acting on an early blood signal improves lung-cancer outcomes.
When a clinical trial or a defined clinical question makes MRD testing relevant, our practice can coordinate interpretation with medical oncology and radiology. Treatment should not be started from a blood result alone.
Neutral product overview
Representative currently available tests
The list below explains categories and is not complete or an endorsement. Availability, indications, FDA status, and insurance coverage change. A test performed by a CLIA-certified laboratory is not necessarily FDA cleared or approved.
| Clinical use | Nonexclusive examples and status |
|---|---|
| Screening adjunct | FirstLook Lung is a commercial laboratory-developed test intended as an adjunct for adults already eligible for low-dose CT. It does not replace CT and is not included in national screening recommendations. |
| Pulmonary-nodule risk adjuncts | Nodify XL2 and Nodify CDT are commercial laboratory-developed tests for selected patients who already have an identified pulmonary nodule. They do not independently establish or exclude cancer. |
| Treatment selection after confirmed NSCLC | Guardant360 CDx / Guardant360 Liquid CDx, FoundationOne Liquid CDx, cobas EGFR Mutation Test v2, and Agilent Resolution ctDx FIRST have FDA-authorized uses tied to defined biomarkers, medicines, and indications. Authorization does not extend to screening or postoperative MRD. |
| Postoperative MRD | Signatera and Guardant Reveal are commercial laboratory-developed MRD tests. Neither is FDA authorized for lung-cancer MRD, and routine use is not established as a national standard. |
We select the type of test according to the question being asked rather than promoting a brand.
Coordinated interpretation
How our office helps
We review the nodule, imaging, pathology, stage, and treatment history; determine whether a blood test is likely to change care; and coordinate the result with thoracic surgery, medical oncology, radiation oncology, and radiology throughout the Merrimack Valley and Southern New Hampshire.
Sources and further reading
Sources reviewed September 12, 2026. This page is educational and does not recommend a specific laboratory or product.
- ASCO: Circulating tumor DNA testing in oncology
- ASCO: Lung cancer surveillance after curative-intent therapy
- CHEST: Lung cancer screening guideline and biomarker evidence
- FDA: Authorized companion diagnostic devices
- Biodesix: Nodify lung-nodule tests (manufacturer source)
- DELFI Diagnostics: FirstLook Lung intended use (manufacturer source)