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Using GIS to Produce Cancer Incidence Maps: A Case Study of Trabzon, Turkey
Statistical Maps for Geographical Analysis
Cancer density of study area is determined and distribution of cancer cases is observed visually is required for geographical analysis. This research can be realized with statistical map regarding cancer cases. Statistical map presentations are required to examine the distribution of cancer data geographically. ESRI ArcGIS 9.x software was used at map production phase. Cancer cases were pointed with point symbol on the map. The geographic distribution of each case can be seen with point symbol on Density Map of Cancer Cases in Trabzon Province (Figure 2). Also, the distribution of cancer cases in view of cancer types can be seen on this produced map. In addition to this, the prevalence of cancer cases based on villages for each county was presented visually.
In the study, the incidence values have been used for statistical examination as the comparison criteria. Calculated incidence values present cancer prevalence in allocation areas. The maps presenting cancer prevalence in Trabzon was produced for province and city center separately. Cancer Density Map of Trabzon Province was formed for each allocation unit as to calculate incidence values (Figure 3).
According to WHO, it is expected that 150-300 people are taken cancer illness for 100.000 population (URL-4). In the produced map, allocation units having incidence value higher than 300 were determined as risky districts in view of cancer density. These figure outs were presented on the map. In the allocation units having incidence value between 150 and 300 have expected results in view of cancer density, according to world standards.
Figure 2: Distribution of Cancer Cases in Trabzon Province of Turkey
Based on the aspect map of Trabzon, skin cancer cases were also examined. Existing skin cancer cases were determined and distribution of these was presented on the map with point symbol. The reason for skin cancer cases is indicated to be exposed sunlight too much (Bingöl, 1978). In this way, the aspect map was used as base map to present skin cancer cases. An aspect map shows solar orientations of slopes with different orientations and districts affected by sunlight so much can be seen on this map. Relation between skin cancer cases and districts affected by sunlight so much can be examined on this map (Figure 4).
Figure 3: Cancer Incidences Map of Trabzon, Turkey.
Figure 4: Skin Cancer Cases overlaid on Aspect layer in Trabzon province
In addition, when cancer cases data are available on city center as a district based, cancer incidence values can also be calculated and related maps also produced for a more focused areas. An example applied for the city center of Trabzon. In Figure 5, calculated cancer incidence values are shown for Trabzon city centre. For the city center it was figured out that incidence value is 143 which can be acceptable incidence values in accordance to the WHO standards.
Figure 5: Cancer Density Map for Trabzon City Centre in district bases.
5. Conclusions
- When the prevalence of cancer cases with point symbol is examined, it is determined that cancer risky regions have more population density than other regions. It can be perceived on the map that allocations areas in coastal regions, across valley, and city center have more cancer cases.
- It was determined that totally 138 allocation units out of 596 in Trabzon exceeded the expected number of cancer cases in 100.000 population. 23% of all allocation units exceeded the value accepted as top limit, 300 incidences.
- The incidence value in Trabzon province was calculated about 118. This value is under expected cancer risk that is accepted between 150-300 regards 100.000 populations.
- When the distributions of cancer are observed in terms of their types, the first most frequently occurring cancer types observed are lung (19%), skin (12%), breast (10%), stomach (9%) and urinary bladder cancer.
- This study can be considered as a pilot application for presenting the distribution of cancer densities on the maps, producing control programs against cancer, and examining environmental factors causing cancer spatially.
- This study proved that cancer data should be collected regularly and quite a few researches about biostatistics and epidemiology can be made. It is firstly emphasized that existing cancer cases in Turkey can be recorded completely.
As a final conclusion, the ability of GIS for comprehensive cancer control, however, comes from the flexibility and extensibility of the digital environment. A GIS-based map has the potential to the capability of classical data to prompt insight about spatial distributions and relationships with the ability of the digital environment to support exploratory analysis, statistical and computational testing of hypotheses, policy decision making, and dissemination of information in a variety of forms. Such products can be integrated to new data continuously and produce new outputs to meet particular cancer researches. It will also provide a framework for extending the GIS functionality over time.
References
- Colak, E. and Yomralioglu, T., 2005. Creating GIS-Based Cancer Density Maps for Trabzon Province of Turkey, ESRI Health GIS Conference, Chicago, Illinois, USA, 2005.
- Colak, H.E., 2005. Cografi Bilgi Sistemleri ile Trabzon Ili Kanser Haritalarinin Üretimi, Yüksek Lisans Tezi, Karadeniz Teknik Üniversitesi, Fen Bilimleri Enstitüsü, Trabzon, 2005.
- Bingöl, Ö., 1978. Deri Kanserleri, Klinik Onkoloji, (ed. Küçüksu M.N. ve Ruacan S.A.), Türk Kanser ve Arastirma Kurumu Yayinlari, Ankara, 23, 419-438.
- DIE, 2002. 2000 Genel Nüfus Sayimi Nüfusun Sosyal ve Ekonomik Nitelikleri Trabzon Ili, DIE yayinlari, DIE Matbaasi, Yayin No:2688, Ankara.
- Özet, A., 2005. Türkiyede ve Dünyada Kanser Epidemiyolojisi, http://www.gata.edu.tr/dahilibilimler/onkoloji/kanser_epidemiyolojisi.htm, 2 Mayis 2005.
- Sengelen, M., 2002. Türkiyede Kanser Istatistikleri, Bilim Uzmanligi Tezi, Hacettepe Üniversitesi, Saglik Bilimleri Enstitüsü, Ankara, 2002.
- Tuncer, M, 2005. http://www.e-kolay.net/haber/haber.asp?HaberID=310727&PID=99, Kaserde Vahim Tablo,22 Agustos 2005.
- URL-1. http://www.un.org.tr/who/bulten/turk/bul7dsobasin51.htm, Kanser Hastalari Ve Topluluklari Için Yeni Bir Umut (DSÖ/52 Basin Bildirisi, 28 Haziran 2002), 20 Mayis 2005.
- URL2. http://www.saglik.gov.tr , Saglik Bakanligi, 09 Haziran 2005.
- URL3. http://surveillance.cancer.gov/statistics/types/incidence.html, National Cancer Institute, Cancer Control&Population Sciences,2005.
- URL4. http://www.roche.com.tr/roche/content/tedavi_alanlarimiz/onkoloji/genel, Genel Risk Faktörleri, 30 Mayis 2005.
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