College of Public Health and Human Sciences

Selenoprotein P (SELENOP) is a major selenoenzyme in plasma and linked to antioxidant properties and possibly to lung cancer; however, supporting evidence is limited. We investigated the association between pre-diagnostic plasma SELENOP concentration and lung cancer risk in a case-control study of 403 cases and 403 individually-matched controls nested within the Shanghai Men's Health Study. SELENOP concentration in pre-diagnostic plasma samples was measured by sandwich ELISA. Cases were diagnosed with lung cancer between 2003 and 2010. Multivariate conditional logistic regression was used to estimate odds ratios (OR) and the corresponding 95% confidence intervals (CI) for the association between plasma SELENOP concentration and lung cancer risk. Cases had slightly lower plasma SELENOP concentration than controls (4.3 ± 1.2 mg/L vs. 4.4 ± 1.1 mg/L, P-difference=0.09). However, the multivariate analysis showed no association between plasma SELENOP and lung cancer risk among all participants (OR=1.08, 95% CI=0.54-2.14 for quartile 4 vs. quartile 1), or by smoking status, or tumor aggressiveness. In contrast, although the number of cases was limited, plasma SELENOP concentration was positively associated with lung adenocarcinoma risk (OR=5.38, 95% CI=1.89-15.35 for tertile 3 vs. tertile 1), but not with lung squamous cell carcinoma (OR=1.69, 95% CI=0.43-6.70). Our study of Chinese men living in selenium non-deficient areas in China provides little support for the inverse association between pre-diagnostic plasma SELENOP concentration and lung cancer risk. Our finding of a positive association with risk of lung adenocarcinoma needs to be interpreted with caution.