Risks of adverse respiratory outcomes in adults with cancer over the course of survivorship compared with cancer-free individuals: a matched cohort study using linked English electronic health records.

BACKGROUND

We aimed to compare the risks of developing new chronic respiratory conditions, or exacerbating existing ones in survivors of 20 common cancers vs. cancer-free individuals.

METHODS

We conducted a population-based matched cohort study using English electronic primary care records, linked to cancer registry, hospital admissions, and death records data from 1999 to 2019. Adults aged ≥ 18 years with incident cancer were matched 1:10 to cancer-free individuals on age, sex and general practice. Outcomes included new-onset and exacerbations of asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, and interstitial lung disease (ILD) ascertained from electronic health record (EHR) data throughout follow-up. Relative risks were estimated using Cox models, adjusted for confounders, like smoking. Absolute risks were estimated using adjusted incident rate differences and standardised cumulative incidence curves for new-onset disease and mean cumulative count for exacerbations.

FINDINGS: 789,254 adults with incident cancer were included. Compared with cancer-free individuals, ILD risk was raised in 18 cancers (adjusted hazard ratio [adjHR] > 5 in CNS, oesophageal and lung cancers, and adjHR > 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 (adjHR 4.69 increased risk for lung cancer; other adjHRs 1.08-1.71); for seven of these cancers, raised risks persisted beyond five years. New-onset bronchiectasis risk was increased in oesophageal, lung and haematological cancers while new-onset asthma risk was raised in non-Hodgkin lymphoma only. Exacerbations rates of pre-existing respiratory diseases were raised in survivors of oesophageal, liver, lung, pancreatic, central nervous system, and haematological cancers.

INTERPRETATION: Survivors of most types of cancer had substantial and sometimes prolonged raised risk of a range of respiratory conditions. Future research should explore the mechanisms underlying these associations, including the roles of post-cancer tobacco use and specific anti-cancer treatments. Targeted management, smoking cessation, and vaccination may be warranted for those at highest risk.

FUNDING: Medical Research Council and Wellcome trust.