Assessment of Clustering of Cutaneous T-Cell Lymphoma in Metropolitan Atlanta Pubblico

Abstract

Background: Cutaneous T-cell lymphoma (CTCL) is a rare type of non-Hodgkin lymphoma (NHL). In the United States, the overall CTCL incidence increased from the year 1973 to 2004 and just started stabilizing in recent decades. The cause of previous increase in incidence remains unknown but was believed to be related with environmental factors. Recent analysis found significant geographic clustering of CTCL at county level in Georgia. There was also correlation between the clustering and an increased concentration of benzene and TCE exposure at county level.

Objective: (1) Identify the geographic clustering of CTCL in metropolitan Atlanta, including five counties: Fulton, DeKalb, Gwinnett, Cobb, and Clayton, at the census tract level. (2) Analyze the correlation of CTCL incidence with ambient benzene and TCE levels.

Methods: The CTCL patients data and chemical toxins data were collected from Georgia Cancer Registry (GCR) and EPA’s National Air Toxics Assessment (NATA) respectively. Standardized incidence ratio (SIR) was estimated for each census tract to assess the incidence of CTCL. Global and local Moran’s I Statistics were used to assess the geographic clustering. Non-spatial generalized linear models were fitted to study the associations between CTCL incidence and chemical toxins exposures. Spatial generalized linear mixed model within a Bayesian setting was also performed because of the small sample size.

Results: Clusters of census tracts with high CTCL incidence and high chemical toxins exposure were found in metropolitan Atlanta. Expected positive correlation between the exposures to benzene and TCE and the distribution of CTCL incidence at the census tract level were not identified. Majority of the results from non-spatial and spatial models were not statistically significant, except those in logistic regression model, where benzene exposures and concentration showed negative correlation with the log odds of CTCL cases.

Conclusions: The results failed to support the previous finding at finer level, but the Bayesian setting model provided a solid theoretical base for study at small geographic unit level. Further CTCL incidence study should be based on larger patients sample size, more detailed patients information, and more environmental toxins. 

Table of Contents

Table of Contents

Introduction.....................................................................................1 Methods...........................................................................................3 Results...........................................................................................13 Discussion.......................................................................................16 Reference........................................................................................19 Tables and Figures.............................................................................23 

About this Master's Thesis

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School	Rollins School of Public Health
Department	Biostatistics
Subfield / Discipline	Public Health Informatics - MSPH
Degree	M.S.P.H.
Submission	Master's Thesis
Language	English
Research Field	Geography Biology, Biostatistics
Parola chiave	Cutaneous T-Cell Lymphoma Spatial Analysis Clustering Bayesian Analysis
Committee Chair / Thesis Advisor	Switchenko, Jeffrey M., Emory University
Committee Members	Liu, Yuan, Emory University

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