Inclusion Criteria:

- Pathologically confirmed diagnosis of NSCLC of adenocarcinoma histology

- Stage IA-B, IIA-B, or IIIA by the American Joint Committee on Cancer 7th edition
staging criteria

- Patients must have undergone surgical resection with curative intent within 6 months
of enrollment

- Sufficient tumor tissue available for EGFR mutation analysis

- At least ONE of the following patient characteristics: previously detected deletion
19 or L858R EGFR mutation, female sex, history of never smoking, or Asian/Pacific Rim
ethnicity (to be enrolled in the screening portion of trial).

- 18 years of age or older

- Tumor samples must have either exon 19 deletion mutations or the exon 21 L858R point
mutation

- ECOG Performance status of 0,1, or 2

- Adequate organ function as outlined in protocol

Exclusion Criteria:

- Radiographic evidence of recurrent NSCLC prior to erlotinib treatment

- Confirmed T790M resistance mutation in the primary tumor sample

- Prior exposure to EGFR tyrosine kinase inhibitors

- Known hypersensitivity to erlotinib, gefitinib, or any closely related drug

- Pregnant or breastfeeding women

- Any evidence of clinically active interstitial lung disease

- Current use of enzyme-inducing anti-epileptic drugs, including carbamazepine,
oxcarbazepine, phenytoin, fosphenytoin, phenobarbital, and primidone

- Evidence of any other significant clinical disorder or laboratory finding that makes
it undesirable for the patient to participate in the study

- Use of any non-FDA approved or investigational agent within 2 weeks of enrolling onto
the trial, or failure to recover from the side effects of any of these agents