A Prospective Study of Plasma Selenoprotein P and Lung Cancer Risk Among Low-Income Adults
Menée aux Etats-Unis à partir des données d'une cohorte en population à faibles revenus ("Southern Community Cohort Study") incluant 372 cas et 716 témoins, cette étude prospective évalue, en fonction de l'appartenance ethnique, l'association entre le niveau sérique de sélénium et le risque de cancer du poumon
Background: Epidemiologic studies have shown increased risks of lung cancer among adults with low blood levels of selenium, although evidence is inconsistent. In the United States the incidence of lung cancer is higher and mean serum selenium levels lower among blacks than whites, but prior studies have not assessed the selenium-lung cancer association among blacks. Methods: From the prospective Southern Community Cohort Study we identified 372 participants who provided blood samples and subsequently developed lung cancer. Selenoprotein P (SEPP1), the most abundant selenoprotein in plasma and a biomarker of selenium nutriture, was measured in the plasma from these individuals and from 716 matched controls. Results: Mean SEPP1 levels were significantly (P<0.0001) lower among blacks than whites. Conditional logistic regression models accounting for smoking revealed a significant trend of increasing odds ratios (OR) of lung cancer with decreasing SEPP1 tertiles among blacks (P =.0006) but not whites (P =.69) (P for interaction =.10). The ORs and corresponding 95% confidence intervals (CI) of lung cancer risk among those with lowest vs highest tertile levels of SEPP1 were 2.4 (1.5-3.0) among blacks and 1.1 (0.6-2.1) among whites. Conclusions: Among a mostly low-income population in the southeastern US, lower levels of SEPP1 were associated with an increasing risk of lung cancer among blacks but not whites. Impact: The combined findings of higher prevalence of low selenium status and higher lung cancer risk associated with low status raise the possibility that selenium deficiency may contribute to observed racial disparities in lung cancer incidence.