Clinical Research Directory

Inclusion Criteria: 1. Age 35 years or greater. If the participant is above the age of 80, participants must be otherwise healthy and well-fit to undergo treatment if lung cancer were to be discovered. 2. Never smoker or quit more than 15 years ago. 3. Able to understand study procedures and to comply with them for the entire length of the study. 4. Ability of individual or legal guardian/representative to understand a written informed consent document, and the willingness to sign it. 5. Length in profession for 10 or more years. This includes both volunteer firefighting and professional firefighting, self-attested as verifiable by professional records. Additional cases for Aim 2: 1. Age 18+, may include deceased firefighters. 2. A previous or current history of confirmed thoracic malignancy (except localized skin cancer, cancer in situ, or other localized cancers) Exclusion Criteria: * Aim 1: 1. Contraindication to any study-related procedure or assessment. 2. Personal history of malignancy within 5 years (except localized skin cancer, cancer in situ, or localized cancers that are definitively treated and are unlikely to recur) or lung cancer at any time. 3. Participants will be assessed for active pregnancy per standard procedure for clinical lung cancer screening CT at University of California, San Francisco which includes asking the participants directly along with documentation of whether the negative pregnancy was self-reported or confirmed with a urine pregnancy test. 4. Prior CT chest within 1 year. 5. Symptoms highly suggestive of lung cancer, including unexplained weight loss of over 30 pounds (lbs) within the past 12 months or unexplained hemoptysis. * Aim 2: No exclusion criteria