Abstract 1871: Ecological association of trace element exposure and lung and colorectal cancer incidence in Southeastern Kentucky
Authors: Shelton Brent J. , Johnson Nancy , Tucker Thomas , Li Li , Unrine Jason , Christian Jay , Huang Bin , Arnold Susanne , Hopenhayn Claudia , Chen Li , Sanderson Wayne , Shi Xianglin 
Published: August 2014

Abstract
Background: Based on National Program of Cancer Registries data from 2002-2006, Kentucky has the highest incidence rate for invasive lung and the second highest rate for invasive colorectal cancer in the US, and these rates may not be fully explained by common risk factors such as smoking. An association between exposure to certain trace elements such as arsenic(As), chromium(Cr) VI, and nickel(Ni) and these two cancers has been documented (As, Cr, Ni in lung and Cr in colorectal). Geologic maps displaying concentrations of As in Kentucky show higher amounts in the Appalachian region compared to the remainder of KY. The objective of this study was to investigate the levels of trace elements in toenail samples from subjects living in southeastern KY compared to subjects living in the urban area of Louisville, KY (Jefferson County). Trace elements in nail samples may indicate environmental exposures and reflect differences in exposure risk across KY.
Methods: Trace element exposure levels were measured in toe-nail samples provided by 503 subjects sampled across 26 KY counties in the southeastern Appalachian region of KY (n=223) and in Jefferson County KY (n=280). The nail samples were analyzed using inductively coupled plasma-mass spectroscopy (ICP-MS) for the metals Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn. Using Kentucky Cancer Registry data from 2003-2007, incidence rates and their 95% CIs for lung and colorectal cancer were compared between southeastern Appalachian KY and the remainder of KY. Trace element concentrations in many samples fell below method detection limits primarily due to limited toenail sample mass. Trace element distributions were estimated using the “Reverse Kaplan-Meier” method for left-censored data. Gamma-based confidence intervals for lung and colorectal incidence rates in each of the two regions were calculated.
Findings: As, Cr, Ni, Se, Cu, Fe, and Pb were found to be significantly higher in southeastern Appalachian KY compared to Jefferson County (all p&lt;0.01). Lung and colorectal cancer incidence rates were also significantly higher in southeastern Appalachian KY (108.89 vs 97.07 and 59.5 vs 55.97; rate per 100,000, respectively). These findings show potentially greater exposure to trace elements for residents of southeastern Appalachian KY and may indicate a cause of greater risk for lung and colon cancer among them. The results of this study provide rationale for further study to assess potential links between trace element exposure and incidence of these two cancers in Kentucky.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1871. doi:10.1158/1538-7445.AM2011-1871