- The E1 Control Group will be drawn from the 866 E1 ECF cases to create a cohort of 260 E1ECF cases. The Control Group for comparison with the Case Group and the Pulmonary Nodules Case Group will be selected at the Biostatistics and Data Management Center (BDMC). The BDMC will match E1 141 controls to the 141 case-group participants with indeterminate but potentially significant findings (E3/E4s). The BDMC will also match 119 E1 controls to the 119 E3/E4 pulmonary nodules cases. Controls will be matched by site, age caliper (5 years), and sex where possible. Where an appropriate match cannot be obtained, the matching criteria will be relaxed. If potential participants decline study consent, we will then best-match additional cases for the appropriate group to maintain target populations. Any additional cases beyond the initial 520 participants identified for medical record collection will be matched as feasible.