Introduction Low-income groups are often less able to practice self-care and are at increased risk of a variety of diseases. Inequality in lung cancer is a major problem and is affecting time to diagnosis and mortality. To promote early detection and to improve outcome, characterization of people at increased risk of lung cancer is required.

Aims and objectives To compare lung cancer patients to matched controls in the year of diagnosis on level and type of income and to assess potential differences among the periods 1980-1993 and 2008-2018.

Methods Using the nationwide Danish Cancer Registry and the Income Registry, all lung cancer patients aged 18-64 years in the period 1980-2018 were identified. The patients were divided into a period I cohort (1980-1994) and a period II cohort (2008-2018). Lung cancer patients were matched with controls at a 1:4 ratio by age, gender, marital status, and municipality at time of diagnosis. Annual income and income from wage and public transfer payment were compared using the 2018 price index.

Results The difference in total income between lung cancer patients and controls were 26% in period I (26,567 ? vs. 33,352?) and 30% in period II (32,812? vs. 42,612?). From period I to period II, the total income increased with 24% for lung cancer patients, and 28% for controls. The income from public transfer payments were unchanged between period I and II in lung cancer patients (11,619? vs. 11,817?) while a decrease was observed in controls (9,450? vs. 8,494?).

Conclusions In this nationwide study 1980-2018, the gap in income between lung cancer patients and matched controls increased. Special attendance towards targeted detection and care of lung cancer should be aimed at low-income groups.