Iressa Case Control Study in Japan

Inclusion Criteria: * Advanced/recurrence NSCLC patients who have had one or more chemotherapy regimens. * Patients who are to be treated with gefitinib or chemotherapy * Cohort: All advanced/recurrence NSCLC patients participating in this post-marketing clinical study Exclusion Criteria: * Patients judged by the investigator(s) to have ILD (provisional cases) among those registered in the cohort OR Randomly selected patients without ILD (controls) for each provisional case * Case-control study: Patients enrolled in the case-control study; all consenting patients with ILD as cases and approximately 4 times as many consenting patients without ILD as controls randomly selected from the cohort