Lung cancer risk elevated in patients with asthma-COPD overlap

Patients with asthma-COPD overlap have elevated risk for lung cancer compared with smokers and similar rates of lung cancer compared with those with COPD, but greater risk than patients with asthma alone, researchers reported.

“Our study provides novel additional data about the [asthma-COPD overlap] phenotype and suggests that in terms of risk of lung cancer, these patients behave closer to those with COPD rather than asthma,” Antonios Charokopos, MD, MSc, assistant professor in the division of pulmonary and critical care at Icahn School of Medicine at Mount Sinai and the Mayo Clinic, Rochester, New York, and colleagues wrote in the Annals of the American Thoracic Society. “These findings also suggest that when assessing the potential indication of lung cancer screening or evaluating the work-up of pulmonary nodules, physicians should consider [asthma-COPD overlap] patients to be at independently increased risk for lung cancer.”

Researchers evaluated the relationship between asthma-COPD overlap and lung cancer risk in 13,939 smokers from the National Lung Cancer Screening Trial with baseline spirometry measures, used spirometric indices and childhood asthma history. To compare unadjusted and adjusted lung cancer risk, investigators categorized participants into the following groups: asthma-COPD overlap with childhood asthma history (n = 208; mean age, 61 years), COPD without childhood asthma history (n = 4,428; mean age, 62 years), smokers with asthma and childhood asthma history (n = 281; mean age, 59 years), Global Initiative for COPD-Unclassified with no airway obstruction but decreased FEV₁ less than 80% predicted without childhood asthma history (n = 2,547; mean age, 61 years) or normal spirometry (n = 6,447; mean age, 60 years).

Among all participants, there were 604 lung cancer cases diagnosed. The incidence rate of lung cancer was 13.2 per 1,000 person-years (95% CI, 8.1-21.5) in the asthma-COPD overlap group, 11.7 per 1,000 person-years (95% CI, 10.5-13.1) in the COPD group, 1.8 per 1,000 person-years (95% CI, 0.6-5.4) in smokers with asthma, 7.7 per 1,000 person-years (95% CI, 6.4-9.2) in the Global Initiative for COPD-Unclassified group and 4.1 per 1,000 person-years (95% CI, 3.5-4.8) in the normal spirometry group.

After adjusting for other risk factors, patients with asthma-COPD overlap had an increased risk for lung cancer compared with patients with asthma (incidence RR = 4.5; 95% CI, 1.3-15.8) and those with normal spirometry (incidence RR = 2.3; 95% CI, 1.3-4.2). However, there was no difference in adjusted lung cancer incidence among patients with asthma-COPD overlap and patients with COPD (incidence RR = 1.2; 95% CI, 0.7-2.1).

According to the researchers, these data may aid in assessing patients for lung cancer screening and estimating the likelihood of lung cancer among pulmonary nodules.

“Future studies, should evaluate the mechanisms mediating the increased risk of lung cancer in this patient group,” the researchers wrote.