Lung Cancer Biomarker Testing: EGFR, ALK, PD-L1 Explained

Why biomarkers changed NSCLC care

Advanced NSCLC is no longer treated as a single disease. Testing the tumor for driver alterations lets clinicians match patients to targeted therapy or immunotherapy rather than defaulting to plain chemotherapy.

The three markers clinicians track

• EGFR mutations sensitize tumors to EGFR tyrosine kinase inhibitors, a standard option in eligible advanced adenocarcinoma.
• ALK rearrangements identify patients who benefit from ALK inhibitors, often with durable responses.
• PD-L1 expression predicts the likelihood of benefit from immune checkpoint inhibitors, used alone or with chemotherapy.

When testing happens

Guidelines recommend broad molecular testing at diagnosis of advanced NSCLC, ideally with a single comprehensive assay so actionable alterations are not missed. Turnaround time matters because it affects first-line choices.

Accurate TNM staging and biomarker status together define the treatment plan.