The rates of chronic obstructive pulmonary disease ( COPD) and lung cancer morbidity in Xuanwei city of Yunnan province are among the highest nationwide , and COPD is an major risk factor for lung cancer .The concur-rence of COPD and lung cancer is a common disease .There are common causative environmental risk factors and pathogenic processes between the two diseases , which provides new ideas for the research , prevention and treatment of both diseases .Additionally the discussion of the relationship between COPD and lung cancer can provide refer -ences for further studies of both diseases .