Background: Delays in lung cancer (LC) diagnosis and treatment adversely affect patient outcomes. Prior studies report mixed results on the association between delays in diagnosis and various demographic factors. Methods: A retrospective cohort analysis was conducted utilizing a randomly selected subset of LC patients treated at the IU Simon Comprehensive Cancer Center between 1/1/18 and 12/31/20. Chart search identified the dates of first suspected cancer finding (SCF; imaging or high-risk presentation), diagnosis, first treating physician contact, and treatment initiation. Patient characteristics (sex, age, race, marital status, insurance status/type, employment status, smoking status, LC stage, LC type) and healthcare utilization (setting of SCF, modality used to discover SCF) were also collected. Asymptomatic patients with SCF at routine screening were excluded. Multivariable Cox proportional hazards and logistic regression models were utilized with significance defined as p < 0.05. Results: Patient characteristics (n = 203): white 86.7%; ever smokers 86.0%; Medicare 61.3%; NSCLC 87.7%; stage IV 44.3%. SCF was primarily identified in an ambulatory setting (57.4%) by CT imaging (62.1%). Median time from SCF to diagnosis, treating physician contact, and treatment were 24d (IQR: 8-67), 24.5d (IQR: 9-54), and 57d (IQR: 28-98), respectively. Median time from diagnosis to treatment was 22d (IQR: 7-41). Time from SCF to LC care was significantly associated with cancer type (median times - diagnosis: NSCLC = 27d, SCLC = 9d, p = 0.001; treating physician contact: NSCLC = 27d, SCLC = 6d, p = 0.002; treatment: NSCLC = 66.5d, SCLC = 23d, p < 0.001), stage (median times - diagnosis: stage I = 52d, stage IV = 9d, p < 0.001; treating physician contact: stage I = 32.5d, stage IV = 13.5d, p = 0.008; treatment: stage I = 97d, stage IV = 23d, p < 0.001), and setting of SCF (median times - diagnosis: ambulatory = 30d, emergency = 7d, p < 0.001; treating physician contact: ambulatory = 31d, emergency = 9d, p < 0.001; treatment: ambulatory = 74.5d, emergency = 28d, p < 0.001). Risk of delays were highest among those with Stage I NSCLC and when SCF occurred in the ambulatory setting. Adjusted by cancer types and modality, patients presenting to the ER were 2.15 times more likely to be diagnosed with stage IV disease than those presenting in the ambulatory setting (p < 0.001). Conclusions: Streamlined transitions of care are needed in the ambulatory setting to reduce delays in LC diagnosis and treatment to optimize patient outcomes. The extended delays experienced by early vs late-stage LC patients may be explained by access to care. However, no demographic factors (insurance, age, race) were significantly associated with delays in this dataset. Further studies are needed to assess the timeliness of cancer diagnosis and treatment in large, diverse populations.