ESTRO 2025 - Abstract Book

S2227

Interdisciplinary – Global health

ESTRO 2025

1567

Digital Poster Geospatial modelling for radiation therapy accessibility in a low-middle income country within Asia Pacific region - Cambodia Boon Yang Jerome Leow 1,2,3 , Geoffrey Paul Delaney 1,2 , Mora Mel 4 , Koeurn Chhoeurt 4 , Mei Ling Yap 1,2,5 1 Collaboration for Cancer Outcomes Research and Evaluation, Ingham Institute, South Western Sydney Local Health District, Liverpool, Australia. 2 School of Clinical Medicine, University of New South Wales, South Western Sydney Clinical School, Sydney, Australia. 3 Radiation Oncology, Nepean Hospital, Nepean Blue Mountains Local Health District, Kingswood, Australia. 4 Radiation Oncology, Calmette Hospital, Phnom Penh, Cambodia. 5 The George Institute for Global Health, UNSW Sydney, Sydney, Australia Purpose/Objective: Cambodia is a low-middle income country (LMIC) within the Asia-Pacific region (APAC) where geographical accessibility to radiotherapy facilities (RTF) remains a challenge. Currently, four radiotherapy facilities (RTFs) are located within the capital city, Phnom Penh. Development of RTFs outside the capital have been delayed due to limited resources. Geospatial analysis has been widely adopted in high-income countries to investigate geographical accessibility where increased distances to RTFs are correlated with poorer oncological outcomes and radiotherapy utilisation (2). However, the impact regarding this approach within APAC LMICs is less known (4). This study aims to quantify geographic accessibility of RTFs within Cambodia and demonstrate the potential impact of developing RTFs in the regional provinces. Material/Methods: The Quantum Geographic Information System (QGIS) software serves as a platform for geospatial data analysis. The geographic distribution of the Cambodian population was sourced from the WorldPOP database. The locations of current RTFs and plans for future developments were obtained from the Directory of Radiotherapy Centres (DIRAC) and discussed with local cancer planners. Euclidean distances to existing and future RTFs were calculated from the centroids of Cambodian provinces. Isochrone maps were generated using the TravelTime and OpenStreetMap Applications. A travel time of 2-hours was used as a definition for geographical accessibility as previous studies have shown a significant fall in radiotherapy utilisation above this level and used in global health as a target timeframe for access to essential healthcare (5). Results: The population count for Cambodia in 2020 is 16,566,056 people. Median Euclidean distance from each provincial centroid to the nearest RTF is 135 km, with the furthest province being 335 km. Proposed future RTFs in Siem Reap and Kampong Cham provinces would reduce the median Euclidean distance to 99 km and the maximum distance to 266 km. Currently, 37.4% of the population lives within a 2-hour driving distance to the nearest RTF. If the proposed RTFs are developed, this percentage would increase to 53%. Conclusion: Current-existing RTFs are geographically inaccessible to most Cambodians. Geospatial modelling has indicated that establishing RTFs in the outer provinces would enhance accessibility. However, only half of the population will lie within the ideal 2 hr travel distance, hence further investments is required. This is a proof of concept that geospatial analysis is a viable and important tool especially in the setting of LMICs. Extending this research to include outcome metrics and other LMICs in the APAC region is required.

Keywords: GIS, developing countries, radiotherapy access

References: 1. Beckett M, Goethals L, Kraus RD, Denysenko K, Barone Mussalem Gentiles MF, Pynda Y, et al. Proximity to Radiotherapy Center, Population, Average Income, and Health Insurance Status as Predictors of Cancer Mortality at the County Level in the United States. JCO Glob Oncol. 2023;9:e2300130.