Table 5.

Basic Characteristics of the First 6 Main Clusters in the Keywords Cluster Atlas of Literature on COPD and Lung Cancer

Cluster ID	Sise	Silhouette	Mean (Year)	Cluster (LLR)	Main Keywords
#0	52	0.885	2003	Lung disease mortality	Obstructive pulmonary disease, prevalence, smoking, asthma, population, air flow obstruction, cardiovascular disease
#1	51	0.929	2003	Expiratory volume	Mortality, morbidity, therapy, lobectomy, predictor, acute exacerbation, exercise capacity, prediction, bronchogenic carcinoma
#2	49	0.956	2002	Anti-p53 antibodies	Expression, association, smoker, biomarker, breast cancer, adenocarcinoma, Pathway, mutation
#3	49	0.931	2004	Lung cancer chronic	COPD, risk, cancer, exposure, cell, computed tomography, cohort, volatile organic compound, dimension
#4	45	0.897	2010	End-stage chronic	Palliative care, burden, exacerbation, of life care, need, China, heart failure, cancer patient, life, China Taiwan
#5	43	0.941	2003	Retrospective proportional mortality study	Risk factor, cigarette smoking, United States, death, coronary heart disease, never smoker