Pulmonary nodules in Denmark: occurrence, resource use, and risk of lung cancer and death

BACKGROUND AND PURPOSE: Little is known about how pulmonary nodules are managed in routine clinical care. We examined their occurrence, the use of computed tomography (CT) scans, referrals to cancer pathways, and the risk of lung cancer and death post-diagnosis. PATIENTS/MATERIAL AND METHODS: We conducted a population-based cohort study using Danish health registry data. We identified all adults with a first-time pulmonary nodule diagnosis from 2018 to 2022. We examined the incidence of pulmonary nodules using age- and sex-standardized incidence rates (SIRs). We used the Aalen-Johansen estimator to calculate the probability of receiving a chest CT scan, a cancer patient pathway referral, the risk of lung cancer, and mortality within 12 months after a nodule diagnosis. RESULTS: We identified 43,209 patients with a pulmonary nodule diagnosis. The age- and sex-SIR of pulmonary nodules was 197 per 100,000 person-years in 2018, declining to 186 per 100,000 person-years in 2022. Within 12 months after a nodule diagnosis, 68.3% of the cohort underwent at least one chest CT scan, with 51.0% receiving a low-dose chest CT scan and 7.2% receiving a referral to a lung cancer patient pathway. The 12-month lung cancer risk was 3.6% (95% CI, 3.4 to 3.8%), with the highest risk for stage I lung cancer, and the mortality was 7.0% (95% CI, 6.8 to 7.3%). INTERPRETATION: The incidence of pulmonary nodules remained relatively stable from 2018 to 2022. More than 30% of patients with nodules lacked a chest CT scan within 12 months after a pulmonary nodule diagnosis.