This observational study will evaluate the patterns of disease progression in patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) harbouring EGFR activating mutations receiving Tarceva (erlotinib) as first-line treatment. Patients will be followed for up to 12 months after progression of disease.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Histologically or cytologically confirmed locally advanced or metastatic (IIIB/IV) non-squamous non-small cell lung cancer (NSCLC) which is routinely evaluated in clinical practice according to RECIST criteria
• EGFR mutation-positive disease according to local laboratory testing
• Patients on treatment with Tarceva monotherapy as first-line treatment according to the physician's usual practice

Exclusion Criteria:

• Prior systemic therapy for advanced NSCLC. The administration of neoadjuvant or adjuvant chemotherapy is allowed as long as it was finalized >6 months prior to receiving Tarceva
• Participation in another clinical study
• Patients could have received radiotherapy as long as the irradiated lesion was not the only lesion for evaluating response and a long as the radiotherapy was completed before initiating Tarceva treatment

Patients with advanced non-small cell lung cancer (NSCLC) with EGFR activating mutations receiving first-line treatment with Tarceva