Abstract A03: Racial and geographic disparities in late-stage prostate cancer diagnosis in Florida.
Authors: Xiao Hong , Goovaerts Pierre , Gwede Clement K. , Tan Fei , Huang Youjie , Adunlin Georges , Ali Askal 
Published: August 2014

Background: Prostate cancer is the most commonly diagnosed non-skin cancer and the second leading cause of cancer death in the United States. Although prostate cancer incidence and mortality have declined recently, striking disparities exist. Visualizing spatial and temporal trends of prostate cancer late-stage incidence, and how they vary based on race, geographic location, income and age may help explain such disparities.

Methods: Individual-level data from the Florida Cancer Data System (1981-2007) were processed to compute: 1) census-tract proportion of late-stage diagnosis for four time periods (1981-1989, 1990-1994, 1995-1999, 2000-2007), and 2) annual statewide proportion of late-stage diagnosis for five classes of income. In both cases, rates were computed for two races (white and black) and two categories of age (40-65, &gt;65). Census-tract level rates were smoothed using binomial kriging to filter the noise caused by small population sizes. Joinpoint regression and three-way contingency analysis were conducted to analyze temporal and spatial trends and detect potential racial differences.

Results: State-level percentage of late-stage diagnosis decreased 50% from 1981 to early 2000; a decline that accelerated in the 90's when prostate specific antigen (PSA) screening was introduced. Bivariate analysis of time-series indicated that late-stage diagnosis was generally more prevalent among blacks compared to whites, for age category 40-64 compared to older patients who are covered by Medicare, and among classes of lower socio-economic status. Joinpoint regression also showed that the rate of decline in late-stage diagnosis for the two racial groups was similar among older patients (i.e. parallel time series). For younger patients, the decline has occurred at a faster pace for black males with rates becoming similar to white males in the late 90s, in particular for classes of higher incomes. Both races display distinct spatial patterns with higher rates of late-stage diagnosis in the Florida Panhandle for white males whereas high rates clustered in South-eastern Florida for black males.

Conclusions: Analyzing temporal trends in cancer incidence and mortality rates outside a spatial framework is unsatisfactory, since it overlooks significant geographical variation which can generate new insights about the potential impact of interventions. This study also showed that temporal trends vary among categories of age and socio-economic status and interact with race. Although joinpoint regression and contingency tables do not allow incorporating all covariates at the same time like a typical regression approach, these plots provide a more intuitive and accessible visualization of temporal trends and interactions, in particular for non-expert users.

Citation Format: Hong Xiao, Pierre Goovaerts, Clement K. Gwede, Fei Tan, Youjie Huang, Georges Adunlin, Askal Ali. Racial and geographic disparities in late-stage prostate cancer diagnosis in Florida. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A03.