This open-label, single arm study will assess the correlation between Tarceva (erlotinib)-induced rash and efficacy in participants with inoperable, locally advanced, recurrent or metastatic non-small cell lung cancer (NSCLC) receiving first-line therapy for advanced disease. Participants will receive Tarceva at a dose of 150 mg daily orally, with dose adjustments according to protocol depending on toxicity. Anticipated time on study treatment is until disease progression, unacceptable toxicity, or withdrawal due to any reason.

Inclusion Criteria:

• Adult participants, >/= 18 years of age
• Inoperable, locally advanced, recurrent or metastatic (Stage IIIB or IV) non-small cell lung cancer (NSCLC)
• Presence of epidermal growth factor receptor (EGFR) mutations
• Previously untreated with any systemic anti-neoplastic therapy for advanced disease
• Last dose of a prior systemic anti-neoplastic therapy for early-stage disease >/= 4 weeks before study start, and patient recovered from acute toxicities of any previous therapy
• A life expectancy of at least 12 weeks
• Able to comply with the study and its follow-up procedures
• Female participants had to be postmenopausal (24 months of amenorrhea), surgically sterile or agree to use a physical method of contraception. Male participants had to be surgically sterile or agree to use a barrier method of contraception. Women with an intact uterus (unless amenorrhoeic for the last 24 months) had to have a negative pregnancy test (urine or serum) within 3 days prior to erlotinib treatment initiation in the study. Male and female participants had to use effective contraception during the study and for a period of 90 days following the last administration of erlotinib. Acceptable methods of contraception included an established hormonal therapy or intrauterine device for females, and the use of a barrier contraceptive (i.e. diaphragm or condoms)

Exclusion Criteria:

• Pregnant or breast feeding women
• Granulocyte count <1.5 x 109/L and platelet count <100*10^9/L
• Serum bilirubin >1.5 upper limit of normal (ULN)
• Aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) > 2 * ULN (or >5 * ULN if clearly attributable to liver metastasis)
• Serum creatinine >1.5 ULN or creatinine clearance <60 mL/min
• Known allergy or other adverse reaction to study drug or any other related compound
• Any significant unstable systemic disease (including active infection, grade 4 hypertension, unstable angina, congestive heart failure, hepatic, renal or metabolic disease)
• Prior systemic anti-neoplastic therapy with HER1/EGFR inhibitors (as small molecule or monoclonal antibody therapy)
• Newly diagnosed or not yet definitively treated (i.e. stable disease >/= 2 months) CNS metastases or spinal cord compression
• Any significant ophthalmological abnormality, especially those likely to increase the risk of corneal epithelial lesions (the use of contact lenses is not recommended during the study)
• Participants who could not take oral medication, who required intravenous alimentation, had had prior surgical procedures affecting absorption, or had active peptic ulcer disease
• Active cancer other than NSCLC, except for basal cell or squamous cell carcinomas of the skin that have been excised and cured