This study utilizes the low dose computed tomography(LDCT) to detect the occurrence of early lung cancer among non-smokers in Taiwan. Subjects who have family history of lung cancer or have high risk exposures to lung cancer will be recruited to participate LDCT screening and followed up for their possible occurrence of lung cancer.

Lung cancer ranks the No. 1 lethal cancer in Taiwan, with a five-year survival rate (5-yr SR) of only 15%. Most of the patients with early lung cancer are asymptomatic, while 75% of patients with cancer-related symptom at diagnosis have local or distant metastasis. Compared to a 5-yr SR of 70-90% in stage I/II lung cancer, the 5-yr SR in late stage IIIb/IV is less than 15%. Despite the progress in pharmaceutical treatment for late stage disease, early detection is still the only way to improve the outcome and even cure of this potentially lethal disease. Low dose computed tomography (LDCT) in recognized as the best tool available for early diagnosis of lung cancer. However, the radiation exposure, high cost and high false-positive rate are the major concerns to adapt this detection tool to general population. Recent studies from Europe and US have shown that LDCT screening in high-risk cigarette smoking population can effectively reduce lung cancer mortality. However, the major type of lung cancer in Taiwan is adenocarcinoma, which commonly occurs in non-smoker. Therefore, the risk prediction model generated from studies of western countries may not be suitable for directly adapted to our country. LDCT screening for lung cancer detection in non-smoker remains a controversial issue worldwide, including Taiwan. Facing the unmet need, it is urgent to establish the risk assessment model to predict lung cancer risks in non-smokers and to evaluate the efficacy of LDCT screening in non-smoker high-risk population. In this study, we plan to enroll 12000 non-smoker subjects with a given lung cancer risk; half of them should have lung cancer family history. Each participant will receive LDCT at baseline, annually for two years, and biennially for 6 years. Our overall goal is to establish a risk assessment model of lung cancer in non-smokers and provide suggestions to government for considerations for lung cancer prevention and screening policy in Taiwan.

There are three specific aims in our proposed study:

Aim 1: To evaluate the risk assessment model for predicting lung cancer in non-smokers According to the results of LDCT screening, we expect to improve the risk prediction model for nonsmoker female established by GELAC study. The revised risk model will help recognizing higher risk population.

Aim 2: To establish the protocol for LDCT screening pilot study in Taiwan Establishing working protocol and procedures of LDCT screening to assure a homogeneous behavior among study sites

Aim 3: To establish the efficacy of LDCT screening for lung cancer in non-smoker Lung cancer detection rate, false-positive rate, and cost-effectiveness analysis of LDCT screening for non-smoker lung cancer in Taiwan will be established.

Inclusion Criteria:

1. Never smokers or have smoked less than 10 pack-years and quitted smoking over 15 years.
2. age from 55 to 75 years for subjects without lung cancer family history; age 50-75 years for subjects with lung cancer family history (age less than 50 but older than the age at diagnosis of the youngest lung cancer proband is also eligible)
3. Having at least one of the following conditions:

(1)with family history of lung cancer within 1st, 2nd or 3rd degree relatives (2)with exposure history of environmental tobacco smoke in workplace or in home (3)history of chronic lung disease (Tuberculosis or COPD) (4)the cooking index equal or over than 110 [cooking index = 2/7 x (days of cooking by pan frying, stir frying, or deep frying in one week) x (cooking years)] (5)cooking without using cooking ventilation

Exclusion Criteria:

1. with history of lung cancer, or with cancers except skin cancer or cervical carcinoma in situ in the past 5 years
2. can not accept invasive diagnostic procedure or surgery
3. have been examined by chest computed tomography in the past 18 months
4. have unexplained hemoptysis in one month
5. weight loss over than 6 kg with unexplained reason among one year
6. pregnant

High risk population for lung cancer