Impact of smoking-related chronic obstruction pulmonary disease on mortality of invasive ductal carcinoma patients receiving standard treatments: Propensity score-matched, nationwide, population-based cohort study

Purpose: the survival effect of smoking-related chronic obstructive pulmonary disease (COPD) and COPD with acute exacerbation (COPDAE) is unclear for patients with invasive ductal carcinoma (IDC) receiving standard treatments. Methods: we recruited women with clinical stage I–III IDC from the Taiwan Cancer Registry Database who had received standard treatments between 1 January 2009 and 31 December 2018. The time-dependent Cox proportional hazards model was used to analyze all-cause mortality. To reduce the effects of potential confounders when all-cause mortality between Groups 1 and 2 were compared, 1:2 propensity score matching (PSM) was performed. We categorized the patients into two groups based on COPD status to compare overall survival outcomes: Group 1 (current smokers with COPD) and Group 2 (nonsmokers without COPD group). Results: PSM yielded 2319 patients with stage I–III IDC (773 and 1546 in Groups 1 and 2, respectively) eligible for further analysis. In the multivariate time-dependent Cox regression analyses, the adjusted hazard ratio (aHR; 95% confidence interval (CI)) of all-cause mortality for Group 1 compared with Group 2 was 1.04 (0.83–1.22). The aHRs (95% CIs) of all-cause mortality for ≥1 hospitalization for COPDAE within one year before breast surgery was 1.51 (1.18–2.36) compared with no COPDAE. Conclusion: smoking-related COPD was not a significant independent risk factor for all-cause mortality in women with stage I–III IDC receiving standard treatments. Being hospitalized at least once for COPDAE within one year before breast surgery is highly associated with high mortality for women with IDC receiving standard treatments. The severity of smoking-related COPD before treatments for breast cancer might be an important prognostic factor of survival. Thus, the information of the severity of COPD before treatment for breast cancer might be valuable for increasing the survival rate in treatment of breast cancer, especially in the prevention of progress from COPD to COPDAE.