Trial Information

Prostate, Lung, Colon, and Ovarian Cancer (PLCO) Screen Trial

Lung cancer is the leading cause of cancer death in the United States. Approximately 90% of
lung cancer is caused by cigarette smoking. While most lung cancer cases occur in smokers or
ex-smokers, only 15-25% of smokers will get lung cancer. Currently it remains impossible to
predict which smokers will get cancer.

Each puff of a cigarette delivers, along with nicotine, a mixture of over 60 known
carcinogens. Most of these carcinogens require metabolic activation before they can
negatively affect cell DNA and cause cancer. Biomarkers that quantify carcinogen levels and
metabolic activity of carcinogens are a useful tool and available to use. The purpose of
this study is to assess the link between tobacco smoke carcinogen biomarkers and the risk of
developing lung cancer.

This observational case-control study will involve a random selection from a group of
smokers who are participating in the Prostrate, Lung, Colon, and Ovarian Cancer (PLCO)
Screen Trial. The chosen cases will include 300 incident lung cancer cases and 300 controls
(participants who have had no diagnosis of lung cancer). Demographic and baseline data from
the PLCO database will be obtained. Prior baseline blood samples from the PLCO trial will be
obtained as well. Based on age, sex, and smoking history, participants will be grouped into
triplets in order to pool their blood samples. These samples will then be analyzed to
determine whether distributions of biomarker levels in lung cancer participants differ from
those in non-lung cancer participants. This study will not involve recruitment of any
participants, as data and samples from the PLCO trial will be used and no new blood samples
will be obtained.