Objectives: To examine whether NK cell activity associates with two confirmed risk factors: (1) presence of indeterminate lung nodule(s) and (2) smoking exposure after controlling for potential confounders, including age, gender, body mass index (BMI), personal history of any cancer, and family history of cancer. This project is aimed at measuring NK cell activity, which may eventually help in reducing false positive rates of LDCT screening, improve early detection of lung cancer, and assist in risk assessment in patients with lung cancer. The investigators hypothesize that measurement of NK cell activity may be a useful tool for assessing changes in immunosurveillance in patients with conditions or diseases where NK cell activity has been shown to be reduced, such as lung cancer

Lung cancer is the leading cause of cancer mortality in the United States. Despite considerable clinical research in multi-modality cancer treatment, there has been no significant decrease in lung cancer-specific mortality over the past three decades. The recent results of the National Lung Screening Trial (NLST) established that screening high-risk individuals using low-dose CT (LDCT) significantly reduces lung cancer-related mortality. One caveat is that approximately 96% of the "positive" results in the NLST were found not to be related to lung cancer. The difficulty in determining which subjects with suspicious lesions should be biopsied or operated on could be alleviated by the development of highly specific lung cancer biomarkers that could complement LDCT. Thus, novel, complementary, non-invasive diagnostic tools with high sensitivity and specificity would clearly be of enormous benefit to patients with a "positive" screening exam. This study will look at measuring the activity of natural killer (NK) cells using the in vitro diagnostic device NK Vue™ in a cohort of current and former smokers (n=100) who meet the criteria for LDCT screening established by the National Comprehensive Cancer Network (NCCN) as a result of the positive findings from the NLST. This project is aimed at measuring the NK cell activity, which may eventually help in reducing false positive rates of LDCT screening, improve early detection of lung cancer, and assist in risk assessment in patients with lung cancer. The Investigators hypothesize that measurement of NK cell activity may be a useful tool for assessing changes in immunosurveillance in patients with conditions or diseases where NK cell activity has been shown to be reduced, such as lung cancer.

Objectives Specific Aim 1: To examine whether NK cell activity associates with two confirmed risk factors: (1) presence of indeterminate lung nodule(s) and (2) smoking exposure after controlling for potential confounders, including age, gender, body mass index (BMI), personal history of any cancer, and family history of cancer.

Specific Aim 2 (Exploratory): In the study cohort, investigators expect approximately 45% of patients having at least one indeterminate lung nodule. Among those with lung nodule(s), investigators will examine whether NK cell activity associates with size of the largest lung nodule after controlling for potential confounders, including smoking exposure, age, gender, BMI, personal history of any cancer, and family history of cancer

Inclusion Criteria:

• At the time of registration, subjects must have a current or previous cumulative cigarette smoking history of ≥ 20 pack years (packs per day multiplied by the number of years smoked). If smoking history is between 20 and 29 pack years, subjects must have an additional risk factor (i.e. radon exposure, occupational exposure, personal history of smoking-associated cancer, family history of lung cancer in first-degree relatives, COPD or pulmonary fibrosis).
• At the time of registration former smokers without additional risk factor(s) must have quit smoking within the preceding 15 years.
• Subjects must be willing to provide blood samples as biospecimens for the study.
• At the time of registration, subjects must have recovered from the toxic effects of prior therapy: ≥6 months (182 days) from the last dose of prior cytotoxic therapy.
• At the time of registration, subjects must have recovered from the effects of prior pneumonia or acute respiratory infection treated by antibiotics by a physician: ≥12 weeks (84 days) from the first dose of antibiotics.

Exclusion Criteria:

• Medical or psychiatric condition precluding informed medical consent.
• Prior history of lung cancer.
• Treatment for or advisement by a physician of evidence of any cancer within the past five years, with the exceptions of non-melanoma skin cancer and most in-situ carcinomas. (Treatment for, or evidence of, melanoma or in-situ bladder/transition cell carcinomas within the preceding five years renders the potential participant ineligible.)

Subjects must be ages 50 to 80 years and 364 days, and are males or females not of childbearing potential.