Changing Epidemiology of Lung Cancer in Finland: A Registry-Based Study by Histology and Region

IntroductionThe national epidemiology of lung cancer (LC) in Finland, subdivided by histology and regional data, has not yet been studied in detail. This study examines the incidence, mortality, and mortality-to-incidence ratios (MIR) of LC and its subtypes in men and women during 2000-2019 in different regions of Finland.MethodsAn observational register-based study was conducted using nationwide data from the Finnish Cancer Registry (FCR). The cases were classified into adenocarcinoma (ADC), squamous cell carcinoma (SQC), small cell lung carcinoma (SCLC), and other and unknown histological types. The incidence and mortality were explored nationwide and separately in the 5 collaborative areas for healthcare and social welfare. MIR were used to estimate survival.ResultsThe incidence and mortality of LC declined in men (78.6 to 25.9/100 000) but increased in women (5.0 to 15.1). The incidence of ADC increased from 4.4 to 7.2, while SQC and SCLC decreased from 5.0 to 3.6 and 3.5 to 3.0. The incidence of ADC increased in men and women, surpassing SQC as the most common histology with varying regional pace. The incidence of SQC and SCLC decreased in men but increased in women. MIR showed similar regional improvements to LC survival for ADC and SQC, but not for SCLC.ConclusionThe Finnish LC rates changed slowly from a predominantly SQC and SCLC histology to ADC being the most common LC type. Sex-specific LC rates are converging nationwide. This study reports detailed Finnish LC data to inform future research and public health efforts.