Matched cohort study of risks of adverse respiratory outcomes in adult with cancer compared with cancer-free individuals

A population-based matched cohort study using English electronic primary care records linked to cancer registry, hospital admission, and death records data from 1999 to 2019 compared the risks of developing new chronic respiratory conditions, or exacerabating existing onse, in survivors of 20 common cancers versus cancer-free individuals. Adult with incident cancer were matched 1:10 to cancer-free individuals on age, sex, and general practice. Outcomes included new-onser and exacerbations of asthma, COPD, bronchiectasis, and ILD ascertained from EHR data throuhout follow-up. Relative risks were estimated using Cox models, adjusted for confounders, like smoking. A total of 789,254 adults with incident cancers. Compared with cancer-free individuals, ILD risk was raised in 18 cancer (aHR >5 in CNS, esophageal, and lung cancers, and aHR ≥ 2 in seven further cancers); raised risks persisted beyond five years after diagnosis in 11 cancers. Elevated risks of developing COPD were observed in 11 cancers (aHR 4.69 for lung cancer; other aHRs 1.08-1.71); for seven of these cancers, raised risks persisted beyond five years. New-onset bronchiectasis risk was increased in esophageal, lung, and hematological cancers while new-onset asthma risk was raised in non-Hodgkin lymphoma only. Exacerbation rates of pre-existing respiratory diseases were raised in survivors of esophageal, liver, lung, pancreatic, CNS, and hematological cancers. The authors conclude that survivors of most types of cancer had substantial and sometimes prolonged raised risk of a range of respiratory conditions.