Patterns of general practice utilization in the period before lung cancer (LC) diagnosis may provide new knowledge to ensure timelier and earlier diagnosis of LC. This study aimed to explore the prediagnostic activity in general practice in the year preceding LC diagnosis. The activity was compared to a matched comparison group. We compared LC patients with different stage, and patients with and without chronic obstructive pulmonary disease (COPD). Using Danish registers, we performed a population-based matched cohort study including lung cancer patients (n = 34,017) and matched comparison subjects (n = 340,170). During months 12 to 1 prior to diagnosis, 92.6% of LC patients and 88.4% of comparison subjects had one or more contacts with general practice. 13.0% of LC patients and 3.3% of comparison subjects had two or more X-rays. 20.8% of LC patients and 8.5% of comparison subjects had two or more first-time antibiotics prescriptions. The incidence rate ratio for having a contact to general practice was similar for LC patients with localized disease compared to LC patients with metastatic disease. LC patients with COPD had more frequent contacts, lung functions tests, X-rays, and prescriptions than COPD patients without lung cancer, but not as pronounced as compared to patients without COPD. There was a significant increase in healthcare seeking and diagnostic activity in the year prior to a LC diagnosis, regardless of stage at diagnosis. COPD may mask the symptoms of LC. This indicates the presence of a "diagnostic time window" and a potential for more timely diagnosis of LC based on clinical signs and symptoms.