Inclusion Criteria - Cases:  Current or past smokers, with at least 20 pack-years Subjects with either A high suspicion for lung cancer, with planned surgery to establish a definitive diagnosis within 60 days after date of blood collection OR treatment naive lung cancer patients  Exclusion Criteria - Cases:  Known diagnosis or treatment of any previous cancer, including lung cancer, in the past 5 years, except for fully resected non-melanoma skin cancer or fully-resected carcinoma in situ of the cervix Current lung cancer is known to be stage III or IV by pathology.  Inclusion Criteria - Screening:  - Current or past smokers, with at least 20 pack-years, undergoing LDCT for lung cancer screening  Exclusion Criteria - Screening:  Known diagnosis or treatment of any cancer, including lung cancer, in the past 5 years, except for fully resected non-melanoma skin cancer or fully-resected carcinoma in situ of the cervix Subjects whose purpose of performing LDCT is for surveillance of a lung nodule