Geographic Accessibility of Radiation Therapy Facilities in Sub-Saharan Africa

Access to radiation therapy in Sub-Saharan Africa (SSA) remains unacceptably low. Prior studies have focused on how many radiation therapy machines a country has but have not accounted for geographic accessibility, which is a known barrier to radiation therapy compliance. In this study, we describe accessibility measured as travel time by road to radiation therapy in SSA. This study used geographic information systems modeling techniques. A list of radiation therapy facilities was obtained from the Directory of Radiotherapy Centres. We obtained a 1 km surface of travel times using a least-cost-path algorithm implemented in Google Earth Engine (Google, Mountain View, CA). AccessMod 5 (World Health Organization, Geneva, Switzerland) was used to compute the percentage of each country's population with access to a radiation therapy facility within prespecified one-way travel time intervals. We then ranked countries using 3 measures of access: 2-hour geographic access, units per capita, and units per cancer case. Only 24.4% of the population of SSA can access a radiation therapy facility within 2 hours of travel by road; access was 14.6% and 42.5% within 1 and 4 hours, respectively. More than 80% of Rwandans and South Africans were within 2 hours of radiation therapy, the highest in the region. Although countries with more radiation therapy units per capita tended to have higher 2-hour access, there was notable discordance between the 2 measures. Mauritania, Zambia, Sudan, and Namibia were among the top 10 countries ranked by machines per capita, but none ranked in the top 10 by 2-hour geographic access. There was similar discordance between 2-hour access and radiation therapy units per cancer case; Rwanda, Nigeria, Senegal, and Cote d'Ivoire ranked in the top 10 for the former but ranked worse using units per cancer case. Prior measures of radiation therapy access provide an incomplete picture. Geographic location of radiation therapy centers is a crucial component of access that should be considered for future planning in SSA.