Naveed Saleh, MD, MS, for MDLinx | December 17, 2018
The severity of chronic obstructive pulmonary disease (COPD) is correlated with overall survival (OS) in lung cancer, and the emphysema-predominant subtype of COPD may predict prognosis in squamous cell carcinoma (SCC), according a recent study published in the International Journal of COPD.
“COPD is an important comorbidity of lung cancer, but the impact of COPD on the outcomes of lung cancer remains uncertain,” wrote authors, led by Wei Wang, Department of Pulmonary Medicine, Qilu Hospital, Shandong University, Jinan, People’s Republic of China. “Because both COPD and lung cancer are heterogeneous diseases, we evaluated the link between COPD phenotypes and the prognosis of different histological subtypes of lung cancer.”
Lung cancer and COPD are intimately tied and share risk factors such as smoking. Previous research has indicated that the risk of lung cancer is increased by two to six times in those with COPD. Researchers have also assessed the association between COPD and prognosis of lung cancer, with mixed results.
In the current retrospective study, the team selected 2,222 patients with newly diagnosed lung cancer (average age: 60.2 years; 1670 men; 1,187 current or previous smokers) of whom 32.6% had comorbid COPD. The researchers performed pulmonary function testing (PFT) on all subjects, and COPD diagnosis was directed by criteria from the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Lung cancer subtypes were determined via World Health Organization (WHO) classification of lung tumors and PFT results. Via Cox regression analysis, investigators determined hazard ratios (HRs), after controlling for age, sex, body mass index (BMI), smoking status, and therapy method.
The team found that COPD was correlated with reduced OS of lung cancer (HR: 1.28, 95% CI: 1.05–1.57). In tandem with heightened COPD severity, lung cancer OS gradually deteriorated (HR: 1.23, 95% CI: 1.08–1.39). Importantly, the emphysema-predominant phenotype of COPD was an independent risk factor for SCC prognosis (HR: 2.53, 95% CI: 1.49–4.30). No association, however, was uncovered between COPD phenotype and lung cancer prognosis in adenocarcinoma, small cell lung cancer, large cell lung cancer, and so forth. Of interest, surgical treatment and high BMI were independent prognostic protective factors.
The possible mechanism by which COPD mediates lung cancer has yet to be elucidated, and identification of such a mechanism is complicated by the heterogeneity in these diseases. Previous research has implicated chronic inflammation, DNA repair capacity, abnormal apoptosis, and comorbidities.
The authors conceded that the current study had limitations. For instance, they were unable to assess the impact of COPD on progression-free survival of lung cancer secondary to a paucity of data; it is also unclear whether COPD plays a role in cancer recurrence.
“Results of this study provide important implications on the research of the mechanism between lung cancer and COPD and contributed to the clinical identification of patients with higher risk for lung cancer prognosis.,” the authors concluded.
This research was funded by the National Natural Science Foundation of People’s Republic of China and the National Key Research and Development Program of China.