Erlotinib, an anti-cancer agent targeting the epidermal growth factor receptor (EGFR), is an active treatment of patients with non-small cell lung cancer (NSCLC). Effect of treatment is primary seen in patients harboring a mutation in the EGFR. However, 10-15% of patients does not harbor a mutation but respond as well. Identifying these patients is a problem and methods are lacking.

Studies have shown that an early 18F FDG-PET might can predict response and outcome in these patients, but further studies are needed to confirm these findings.

Inclusion Criteria:

• Lung Cancer patients with non-small cell histology and stage IV disease
• candidate for erlotinib treatment as first/ second/ third line of treatment

Exclusion Criteria:

• pregnancy
• severe dyspnoea