COPD Is an Independent Risk Factor of Colorectal, Liver, Other Cancers

Regardless of smoking status, chronic obstructive pulmonary disease (COPD) is an independent risk factor for developing lung, colorectal, liver and other cancers in the Korean population, according to a study published in BMC Pulmonary Medicine.

COPD is a leading cause of death in the United States, while the disease is estimated to affect 16 million Americans, and millions more who are unaware they have the condition. Although COPD is a well-known risk factor for lung cancer, “it has not been reported yet whether COPD can be a risk factor for cancers developing outside of the lungs despite the evidence that systemic inflammation is the characteristic feature of COPD,” the researchers wrote.

In a retrospective population-based study, investigators analyzed data from the National Health Insurance Service-National Sample Cohort (NHIS-NSC), a single-payer health insurance system in South Korea that covers the entire population.

Over 12 years, data from 6 different cohorts were assessed, including 313,533 never-smokers without COPD, 41,359 former smokers without COPD, 112,627 smokers without COPD, 7789 never-smokers with COPD, 1085 former smokers with COPD, and 2677 smokers with COPD.

The study yielded the following results (P <.01 for all):

• Higher rates of lung cancer development were seen in never-smokers with COPD (7.82%), former smokers with COPD (11.89%), and smokers with COPD (14.87%) compared with never-smokers without COPD (2.44%)
• Incident rate of lung cancer per 100,000 person-years was higher in the smoking and COPD cohort (216 in non-COPD and 757 in COPD among never-smokers, 271 in non-COPD and 1266 in COPD among former smokers, 394 in non-COPD and 1560 in COPD among smokers)
• Prevalence of lung cancer, stomach cancer, colorectal cancer, liver cancer, esophageal cancer, bladder cancer, and kidney cancer was higher according to smoking history and COPD diagnosis
• Old age, male sex, lower body mass index, low exercise level, history of diabetes, smoking, and COPD were independent factors associated with the development of lung cancer
• COPD in never-smokers, former smokers, and current smokers contributed to the development of colorectal cancer and liver cancer among other major cancers

“Repeated injury and repair by chronic inflammation and frequent exacerbations in COPD may result in tissue injury and DNA damage, leading to malignant cell transformation and the development of lung cancer,” researchers explained. In addition, clinical evidence has found emphysema and severe airflow obstruction can increase the risk of lung cancer beyond the effect of smoking.

Due to limited information in the NHIS-NSC, the pathologic type of each cancer was not investigated while medication history was also not taken into consideration in the analysis. Environmental factors like air pollution and occupation were also not included.

Authors concluded the findings suggest “multidisciplinary approaches are required for the prevention of lung cancer in COPD patients."

Reference:

Ahn SV, Lee E, Park B, et al. Cancer development in patients with COPD: a retrospective analysis of the national health insurance service-national sample cohort in Korea. BMC Pulm Med. Published online June 15, 2020. doi:10.1186/s12890-020-01194-8