Influence of Serum Lypocene on Lung Cancer Mortality: An 18-Year Follow-Up Study of a National Cohort

A potent antioxidant, lycopene, is the most abundant and naturally-occurring carotenoid in tomatoes and tomato-based foods. It is frequently found in pink grapefruit, watermelon, guava, and papaya; and it provides fruits and vegetables their red and pink colors. Lycopene promotes high levels of free-radical scavenging compared to other carotenoids such as β-carotenoids. It inhibits cellular proliferation, angiogenesis, and metastasis through multiple biochemical pathways. Epidemiological studies suggest that consumption of lycopene-rich foods is associated with decreased risk of prostate, lung, breast and GI tract cancers. To our knowledge, influence of lycopene on lung cancer mortality has not been characterized. Thus, the objective of this study was to determine whether there is an association between serum lycopene levels and lung cancer mortality. A retrospective cohort study was conducted with 14,358 adult participants in phase II of the National Health and Nutrition Examination Survey III (1991-1994) (NHANES III). This served as baseline and was correlated with the National Death Index database for a 15 year (1991-2006) follow-up study. Hazard ratios (HRs) for all-cause and cancer-related deaths for individuals with high, medium, and low serum lycopene levels were calculated using the Cox Proportional Hazards Regression Model. The unadjusted HR of deaths associated with low serum levels (25% cutoff) of lycopene were 1.67 (95%CI=1.24-2.23) and 1.00 (ref). After adjusting for multiple risk factors such as age and sex, the HR for lung cancer mortality were 1.00 (ref) and 1.45 (95%CI=1.08-1.96) for low serum levels (25% cutoff). Adjusted HR for lung cancer death using 3-level categorization (and adjusted for fruits and vegetables) was 1.67 (95%CI=1.03-2.71) for low vs. high levels of lycopene. Also, adjusted HR for lung cancer death using 3-level categorization (and unadjusted for fruits and vegetables) was 1.68 (95%CI=1.04-2.72) for low vs. high levels of lycopene. Results suggest that high serum lycopene levels significantly reduce the risk of death from lung cancer. Thus, not only does lycopene decrease risk of lung cancer development, it also decreases lung cancer mortality. Further studies are needed to explain the physiological mechanisms of this phenomenon.