Defense Date

2009

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Epidemiology & Community Health

First Advisor

Saba Masho

Second Advisor

Tilahun Adera

Third Advisor

Viswanathan Ramakrishnan

Fourth Advisor

John Roberts

Abstract

This is a compilation of 3 abstracts for the three manuscripts included in this dissertation. I. Meta-Analysis: Racial Disparities in Prostate Cancer Survival: Prostate cancer is the second leading cause of cancer-related mortality in men. Previous studies have drawn inconsistent conclusions on racial differences in prostate cancer survival. This meta-analysis was conducted to investigate the relationship between race and survival from prostate cancer. A systematic review of published articles from 1968 to 2007 assessing survival from prostate cancer among African American and White men was conducted. The search yielded 20 eligible published manuscripts. Analysis of unadjusted studies showed African American men have an increased risk of all-cause mortality (Hazard ratio (HR) = 1.47, 95% confidence interval (CI): 1.31, 1.65, P < 0.001). However, examination of adjusted studies showed no difference (HR = 1.07, 95% CI: 0.94, 1.22, P = 0.308). No statistically significant difference was observed in prostate cancer-specific survival in both analyses using unadjusted (HR = 1.11, 95% CI: 0.94, 1.31, P = 0.209) and adjusted studies (HR = 1.15, 95% CI: 0.95, 1.41, P = 0.157). There was evidence of heterogeneity that was unexplained by factors analyzed in overall survival but explained by stage in prostate cancer-specific survival. This meta-analysis concludes that there are no racial differences in the overall and prostate cancer-specific survival between African American and White men. II. Case-Control study: Association between Family History of Cancers and Prostate Cancer: Family history of prostate cancer is an established risk factor for prostate cancer. However, the relationship between family history of cancers other than prostate cancer and prostate cancer risk is inconclusive. This study sought to examine the association between family history of cancers and prostate cancer. A case-control study was conducted in which cases and controls were randomly selected from a large urology clinic in Central Virginia. Cases were 600 histologically confirmed prostate cancer patients who were diagnosed between January 2000 and December 2005, and controls were 686 patients who visited the clinic during the same period and diagnosed with urological illnesses other than cancers and prostate-related problems. Data on family history of cancers, lifestyle and demographic factors were collected. Unconditional logistic regression analysis was used to estimate the odds ratios and the corresponding 95% confidence intervals after adjustment for potential confounding factors. Multiple comparisons adjustments were made using Bonferroni adjustment. Men with family history of any cancer in first-degree relatives including parents (OR=2.42, 95% CI: 1.53, 3.84) and parents only (OR=1.90, 95% CI: 1.23, 2.94) were at increased risk of developing prostate cancer compared to men with no such family history of cancer. Significant increased risk was also observed with family history of prostate cancer in first-degree relatives (OR=2.68, 95% CI: 1.53, 4.69) and parents only (OR=3.26, 95% CI: 1.71, 6.24) compared to men with no family history of prostate cancer. Even after adjustments for multiple comparisons, the significance persisted both in first-degree relatives (OR=2.68, 95% CI: 1.16, 6.21) and parents alone (OR=3.26, 95% CI: 1.24, 8.63). No association was found with family history of other cancers including breast, colon, lung, skin, digestive tract, stomach, liver, pancreas, female cancers, urogenital, urinary bladder, brain, blood and lymph node and other cancers and risk of prostate cancer. This study demonstrated an increased prostate cancer risk for men with a family history of any cancer or prostate cancer in first-degree relatives including parents and parents alone. Health care providers need to be aware of the potential risk of family history of cancers on prostate cancer. III. Case-Control study: Association between Obesity and Prostate Cancer: Obesity is a major public health problem in the United States. Several studies have investigated the association between obesity and prostate cancer risk. However the impact of early-adult obesity on prostate cancer is not well studied. This study proposes to investigate the relationship between prostate cancer and early-onset obesity and current obesity. A case-control study was conducted to investigate the relationship between obesity and prostate cancer in a large urology clinic population in Central Virginia. Cases included histologically confirmed prostate cancer patients of all stages and grades diagnosed from January 2000 to December 2005. Controls were patients who were diagnosed with urological illness other than cancers and prostate-related problems. Self-reported data was collected on anthropometric, lifestyle and demographic factors through a mail survey. Unconditional logistic regression analysis was conducted to investigate the association between prostate cancer and early-onset obesity (BMI at age 18) and current obesity. Odds ratios and corresponding 95% confidence intervals were calculated after accounting for significant interaction terms and adjusting for potential confounding variables. This study showed statistically significant association between BMI at age 18 and prostate cancer risk in the multivariate analysis when BMI was evaluated as a continuous variable. There was a 7% decrease in the odds of prostate cancer risk for every 1 kg/m(2) increment in BMI at age 18 (OR=0.93, 95% CI: 0.87, 0.98). Analysis of BMI at age 18 as a categorical variable also showed reduced risk though statistically non-significant. Obese men (OR=0.62, 95% CI: 0.12, 3.08) and overweight men (OR=0.60, 95% CI: 0.35, 1.05) had a non-significant decreased risk of developing prostate cancer compared to normal weight men at age 18. Examination of current BMI showed a non-statistically significant decreased risk of prostate cancer when examined as a continuous variable. However, there was significant interaction between current BMI treated categorically and age. This study concludes that there is decreased prostate cancer risk associated with increasing BMI at age 18. Future large prospective studies are needed to better understand the association between early-onset obesity and risk of prostate cancer and explore the biological factors associated especially in the early ages. This document was created in Microsoft Word 2003.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

May 2009

Included in

Epidemiology Commons

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