Implication of insulin-like growth factor (IGF)/IGF binding protein-3 and alpha-tocopherol in the chemopreventive activity of 9-cis retinoic acid in lung cancer

1005 Background: High level of IGF-I is associated with increased susceptibility for several types of cancer, whereas high levels of IGFBP-3 and vitamin E tend to attenuate the risk. This study was designed to investigate whether 9-cis-retinoic acid (9cRA) treatment affects the serum IGF-I/IGFBP-3 and alpha-tocopherol (AT), the most active form of vitamin E. Experimental Design: Individuals (n = 226) who had smoked at least 20 pack-year (PY) and had ceased smoking for at least 12 months were randomly assigned to receive 3 months of daily oral 9cRA (100 mg) or placebo arm. During the clinical trial, participants were informed to visit every month and blood samples were taken. After treatment, participants were followed up for another 3 months. Serum levels of IGF-I, IGFBP-3, and AT of participants, who were enrolled in 9cRA (n=49) and placebo (n=55), were measured by the use of HPLC. All statistical tests were two-sided. Results: In 9cRA group, the levels of IGF-I and IGF-I:IGFBP-3 molar ratio were signifi...