<scp>COPD</scp> and Lung Cancer: Shared Risks and Connections

I was honoured to participate in a conference at the beautiful city of Shanghai, China last month, where I presented on the topic of “Early Life Exposures and Shared Risk Factors for chronic obstructive pulmonary disease (COPD) and Lung Cancer.” In preparing for this presentation, much like I do for my other lectures, I deepened my understanding of the subject. However, I also discovered that many unanswered questions remain regarding the connections between these two significant and prevalent diseases. The Lancet Commission, published in 2022, proposed a classification system for COPD based on major risk factors, which include genetics, early life events, infections, smoking, and exposure to environmental tobacco smoke and other environmental factors (https://www.thelancet.com/commissions/COPD). Similarly, the risk factors for lung cancer encompass smoking, genetic predispositions, exposure to carcinogens such as radon, asbestos, and polycyclic aromatic hydrocarbons, air pollution, and a history of human immunodeficiency virus infection (HIV), tuberculosis, and pulmonary fibrosis (https://www.lung.org/lung-health-diseases/lung-disease-lookup/lung-cancer/basics/what-causes-lung-cancer). Notably, many risk factors overlap between COPD and lung cancer, particularly smoking, environmental exposures, and previous infections. While smoking is a common risk factor for both conditions, COPD also serves as a significant independent risk factor for lung cancer in individuals who have never smoked (https://doi.org/10.1136/thoraxjnl-2019-213732) (https://doi.org/10.1183/09031936.00144208). The underlying predispositions for both diseases may stem from several factors, including genetic predisposition, telomere shortening, mitochondrial dysfunction, and premature aging. COPD may also play a significant role in the development of lung cancer through various mechanisms. It can elevate oxidative stress, leading to increased DNA damage, and promote chronic exposure to pro-inflammatory cytokines, which further exacerbates the situation. Additionally, COPD can suppress DNA repair mechanisms and stimulate cellular proliferation, contributing to the progression of lung cancer (https://doi.org/10.1016/j.lungcan.2015.08.017). Upon reviewing the literature, I have not found complete answers to some questions. For example, why do some patients with COPD develop lung cancer while others do not? Do different etiologies of COPD, such as smoking, exposure to biomass, ambient air pollution, early life events, or a history of infections, carry varying risks for the development of lung cancer? Specifically, which factors pose higher or lower risks, and to what extent? Additionally, is there a difference in the histology of lung cancer based on these etiological factors, and how might this affect prognosis and progression? Moreover, could the mechanisms by which individuals with COPD develop lung cancer differ depending on their specific circumstances, such as those who smoke, those exposed to particulate matter, or individuals with a history of tuberculosis? As I delve deeper into the references, my questions only seem to multiply. The author declares no conflicts of interest.