Impact of Chronic Obstructive Pulmonary Disease on the Mortality of Patients with Small Cell Lung Cancer

Background: Limited studies have focused on the impact of the coexistence of small cell lung cancer (SCLC) and chronic obstructive pulmonary disease (COPD). The study was to examine the impact of COPD on mortality in SCLC patients.

Methods: We analyzed SCLC patients from the Taiwan Cancer Registry Database between January 1, 1997, and December 31, 2015. The COPD population was composed of patients with a COPD diagnosis before the diagnosis of SCLC. The control group was composed of randomly selected SCLC patients without COPD who were propensity score matched with those with concomitant COPD according to age, sex, index date, cancer staging and comorbidities at a 1:1 ratio.

Results: Among 9425 SCLC patients in the database, eligible subjects were divided into the COPD group (n = 4235) and the non-COPD group (n = 2334). Compared to patients in the non-COPD group, the patients in the COPD group were older (71.4 versus 65.7 years, p<0.0001), had a lower percentage of stage IV disease (60.1% versus 68.3%, p<0.0001) and had more comorbidities. After matching, there were 1457 patients in each group. Older age, lower body mass index (BMI), and some comorbidities were associated with higher mortality, and comorbid COPD was associated with lower 1-year mortality in SCLC patients. Multivariate analysis identified older age, lower BMI, and concomitant congestive heart failure or diabetes as risk factors for OS.

Conclusion: A diagnosis of COPD was associated with reduced 1-year mortality in SCLC patients, but no significant difference after 1-year in this population.