As a part of the continuing translational research efforts on LP against lung cancer, in this correlative and biomarker-based study, we used available archived specimens with matched pre- and post-treatment spot urine samples from our phase I lung cancer chemoprevention study with LP, simultaneously measured F, E, 6β-OHF and 6β-OHE, and compared the ratios of (6β-OHF + 6β-OHE)/(F + E) to define the effects of oral LP on CYP3A4 activity. This evidence concerns the gene CYP3A4 and lung cancer.