Abstract
Geographic disparities in cancer outcomes represent a critical health equity challenge, with rural populations consistently experiencing poorer outcomes than urban populations. The lack of harmonised rurality measures creates substantial barriers to evidence synthesis and has precluded meta-analyses. This perspectives paper discusses concepts of rurality, identifies rurality classification systems used by cancer researchers in OECD countries that can be harmonised with the OECD Extended Typology, and develops recommendations for consistent rural-urban coding. Targeted searches of grey and published literature on cancer policy and rurality classification systems were conducted. The secondary analysis examined studies identified through systematic database searching of OVID Medline, Elsevier Embase, CINAHL, and Web of Science. From 289 studies across 22 OECD countries, twenty-seven rurality classification systems were identified, with eleven systems harmonised to create the Rural-Urban Classification System Harmonisation Framework featuring a consistent five-point rurality scale and standardised urban-rural dichotomisation. Implementation recommendations address system selection, standardised categorisation, and reporting standards. Adopting this harmonisation framework will improve research comparability and strengthen evidence to inform equitable cancer policies. FUNDING: Commonwealth of Australia's Medical Research Future Fund (MRF2030313).