Background: Lung cancer is the leading cause of cancer-related deaths worldwide. Before beginning lung cancer treatment, it is necessary to complete procedures such as suspecting lung cancer, obtaining a pathologic diagnosis, and staging. This study aimed to investigate the processes from suspicion of lung cancer to diagnosis, staging, and treatment initiation. Methods: The study was designed as a multicenter and cross-sectional study. Patients with lung cancer from various health institutions located in all geographic regions of Turkey were included in the study. The sociodemographic and clinical characteristics of the patients, the characteristics of the health institutions and geographic regions, and other variables of the lung cancer process were recorded. The time from suspicion of lung cancer to pathologic diagnosis, radiologic staging, and treatment initiation, as well as influencing factors, were investigated. Results: The study included 1410 patients from 29 different medical centers. The mean time from the initial suspicion of lung cancer to the pathologic diagnosis was 48.0 ± 52.6 days, 39.0 ± 52.7 days for radiologic staging, and 74.9 ± 65.5 days for treatment initiation. The residential areas with the most suspected lung cancer cases were highly developed socioeconomic zones. Primary healthcare services accounted for only 0.4% of patients with suspected lung cancer. The time to pathologic diagnosis was longer in the Marmara region, and the wait time for staging and treatment initiation was longer in Eastern and Southeastern Anatolia. Patients who presented to chest disease referral hospitals with peripheral lesions, those with early-stage disease, and those who were diagnosed surgically had significantly longer wait times. Conclusion: The time between pathologic diagnosis, staging, and treatment initiation in lung cancer was longer than expected. Increasing the role of primary healthcare services and distributing socioeconomic resources more equally will contribute to shortening the time to diagnosis and improve treatment processes for lung cancer.