This prospective observational study will evaluate the efficacy and safety of second-line Tarceva (erlotinib) in patients with previously treated advanced non-small cell lung cancer with confirmed wild-type epidermal growth factor receptor (EGFR) gene. The aim of the study is to identify from baseline clinical and demographic patient characteristics prognostic factors related to overall survival with second-line Tarceva treatment. Data will be collected from eligible patients for up to 2 years.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Histologically or cytologically confirmed locally advanced or metastatic non-small cell lung cancer (NSCLC)
• Patients with known wild-type EGFR gene; patients with unknown EGFR mutation status are allowed if they fulfil the following criteria:
• squamous cell carcinoma lung cancer histology, and
• current smoker, or former smoker who has stopped smoking less than 10 years ago and has had a total of >15 pack-years of smoking
• Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2
• Patients having failed one prior chemotherapy regimen and eligible for a second-line treatment with Tarceva

Exclusion Criteria:

• Current treatment with an investigational drug or participation in another investigational study
• Severe or uncontrolled systemic disease, active infection, concomitant malignancy or a second primary malignancy except for in situ carcinoma of the cervix or adequately treated basal cell carcinoma of the skin
• Clinically active interstitial lung disease
• Recent myocardial infarction or unstable angina
• Progressive or uncontrolled brain metastases

Patients with previously treated advanced NSCLC, with wild-type EGFR gene or squamous cell carcinoma histology