By reducing inflammation in the airways — a cause of COPD and lung cancer — ICS could become the first proven chemopreventative for lung cancer. But only high-dose ICS appear to be beneficial.
The latest study showed that COPD patients using over 1,200µg of ICS daily had less than half the risk of developing lung cancer as non-users of ICS.
The findings come from a four-year follow-up study of 10,474 US army veterans with COPD. They were mostly male and aged an average of 65 years.
Of the 517 patients adherent to ICS therapy, 219 were on the higher daily dose of 1,200µg or more.
Overall, 4 per cent of the study group developed lung cancer during follow-up. But only 2.2 per cent of patients using over 1,200µg ICS daily developed lung cancer.
After adjusting for smoking, previous cancers, comorbidity and bronchodilator use, the risk of lung cancer was found to be 60 per cent lower in high-dose ICS users than in non-users.
Analysis of the 517 ICS users alone showed a dose-dependent relationship, with the risk of lung cancer falling by 10 per cent for every 100µg increase in ICS after adjustment for confounders.
The researchers say that chronic inflammation in the lungs of COPD patients might result in a high rate of cell turnover, increasing the risk of genetic errors which could cause lung cancer.
But whether reducing inflammation in the lungs with high-dose ICS can prevent cancer still needs further study.
David Price, professor of respiratory medicine at Aberdeen University and member of General Practice Airways Group, said: ‘I think these are fascinating findings but we do need to be cautious in interpretation — it was only the small subset of patients with high-adherence to high-dose ICS who appeared to derive a benefit from ICS in terms of protection against lung cancer.
‘It could be something else about these individuals that gave them protection.’