D-Dimer Elevation in Lung Cancer: Non-Specific Marker Requiring Comprehensive Diagnosis

D-Dimer: Fibrin Degradation Product

D-dimer reflects fibrinolysis (clot breakdown). Elevated in any condition with thrombin generation + plasmin activation.

Common Causes of Elevated D-Dimer

• Venous thromboembolism (DVT, PE)
• DIC, sepsis, trauma, surgery
• Pregnancy, postpartum
• Inflammatory/autoimmune diseases
• Malignancy (many cancers, including lung)
• Age, renal impairment, hospitalization

Lung Cancer Context

• Tumor procoagulant activity (tissue factor, cancer procoagulant) → microthrombi → ↑ D-dimer.
• Paraneoplastic syndromes, chemotherapy, central lines add risk.
• But: D-dimer lacks specificity; cannot diagnose, stage, or monitor lung cancer alone.

Lung Cancer Diagnostic Pathway

1. Clinical suspicion (symptoms, risk factors)
2. Imaging: CXR → CT chest (± PET-CT)
3. Tissue diagnosis: biopsy (bronchoscopy, CT-guided, EBUS, surgical)
4. Molecular profiling (EGFR, ALK, ROS1, PD-L1, etc.)
5. Staging (TNM)

D-dimer may support VTE workup in cancer patients, but never replaces histologic confirmation.