Lung cancer is a unique disease in which carcinogens, such as industrially produced addictive substances, are the main causative factors. Approximately 85 to 90 percent of lung cancer cases are caused by active or passive (secondhand) smoking. To reduce lung cancer mortality, effective public health policies that begin with strict control of smoking are needed. Continued smoking can lead to second primary cancers and is associated with complications from treatment, drug interactions, the onset of other smoking-related diseases and reduced quality of life, and can shorten life expectancy. The official CDC report states that both active smoking and secondhand smoke can cause lung cancer. Evidence suggests that living with a smoker and smoking secondhand smoke is associated with a 20 to 30 percent increased risk of lung cancer. According to the World Health Organization, health and related authorities should inform everyone about the health risks and addictive nature of smoking and secondhand smoke, and develop effective laws and regulations to protect all people from the dangers of tobacco. Further research indicates that the delivery system of lung carcinogens also contains the highly addictive substance, nicotine. The American Health Care Research and Quality (AHRQ) guidelines state that in order to reduce lung cancer mortality, a very large number of facilities are needed to provide identification, counseling, and treatment services for patients with nicotine addiction. Patients who currently smoke or have a history of smoking have a high risk of developing lung cancer, and drugs to prevent cancer risk in these patients have not been developed. If possible, these patients should be encouraged to participate in relevant clinical trials of drugs to prevent lung cancer. NCCN guidelines recommend low-dose CT (LDCT) to screen for lung cancer in high-risk smokers and those with a history of smoking.