Agenda - 06-13-2006-7a - Laserfiche WebLink

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~~ 4 Clusters of rare cancers. Because lung, breast, colon, and prostate cancers are so common, it is very difficult to find any association between them and exposures in a community. These analyses are done on a tiered basis, starting with the county rates, to ensure stable rates and to identify potential cancer sites or age groups of concern, The results of this analysis were used to focus on the smaller study area, in particular, the Mill Creek Area of Orange County, Geographic Analysis Delineation of a study area was a central focus of this study.. A primary concern to some homeowners is the incidence of naturally occurring arsenic in wells. Because not all privately maintained wells in Orange County or in the Mill Creek area have been tested for arsenic, it was not possible to accurately delineate a study area based on that criterion. Instead, the study area delineation focused on a set of addresses submitted to the North Carolina Central Cancer Registry by the Orange County Health Department, which were used in a subsequent survey of homeowners. The initial study area comprised of two Census Block Groups used by the Census Bureau for the 2000 U S. census, which encompassed these addresses. The Census Bureau identifier numbers for these Block Groups are 1350108012 and 1350111012 (see attached exhibit). To garner input on the study area, the CCR submitted this study area at an early stage in the analysis to the Orange County Health Department for their review and the study area was finalized to include the two aforementioned Census Block Groups. All bladder, liver, melanoma and Tung cancer cases were identified for the time period 1990-2003 in the CCR database for Orange County, for cases whose city of residence at time of diagnosis was Mebane, and all records for which the ZIP code at time of diagnosis was 27302. These records were geocoded using a combination of county-maintained digital parcel-derived addresses, and vendor-maintained digital street centerlines, The geocoding success rate was 98%, for records that had a geocodeable street address. A rigorous attempt was made to geocode every record based on street address, city and ZIP code, A total of 57 records were geocoded to within the study area. The CCR has no residential, occupational or medical histories about cases, The CCR uses the residence at the time of diagnosis as provided by the diagnosing facility to analyze cases by residence. It is recognized that this may not be the relevant address in terms of etiology for a disease with a long latency period, especially given the mobility of many populations. However, since we do not know at what point the disease process that was later diagnosed as a malignant tumor actually began, it is not possible to know what the relevant address is The focus of the CCR is on cancer surveillance, and hence, we use the address at diagnosis. This approach is consistent with procedures used by all other cancer registries in the United States including the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) program, the North American Association of Central Cancer Registries, and the Centers for Disease Control and Prevention. Incidence rates for a chronic disease with a long latency period are useful for disease surveillance, but they may not be good indicators for investigating the etiology of a disease. The CCR also uses the date of diagnosis as provided by the reporting facility to determine in which year to classify each case, Page .36 of 47