How equity in cancer services has been defined and measured, and why it matters: a scoping review of Universal Health Coverage systems.

Cancer equity is a global priority, particularly within Universal Health Coverage systems that are committed to reducing disparities in access and outcomes. However, practical barriers to addressing inequities persist, such as varying definitions and clinical measurements. This inconsistency leads to a reliance on data that does not accurately reflect existing inequities or progress towards equitable care. Commonly reported measures are often aggregate, population-level indicators, such as cancer incidence and mortality, which fall outside the scope of health services and clinicians to influence. A detailed protocol and search strategy were developed a priori, following the Joanna Briggs Institute Reviewer's Manual. Systematic searching was conducted via PudMed Central, CINAHL EBSCO and Cochrane, resulting in 53 studies meeting the selection criteria for analysis. Only eight (n = 8) studies offered definitions of equity, commonly emphasising accessible health services that support optimal health outcomes and the elimination of financial barriers. Seven (n = 7) main equity-related exposures or populations were associated with experiencing cancer inequities: ethnic minority or migrant populations, low socio-economic status, geographic location or remoteness, experiencing severe mental illness, low health literacy, high comorbidities, and those with a disability. A total of fifty-nine (n = 59) individual measures were utilised to demonstrate inequities. The absence of standardised, reproducible data undermines cancer equity efforts, as ad hoc reporting can misrepresent disparities or perpetuate the statistical invisibility of disadvantaged populations. This review aimed to summarise how equity has been defined and measured within UHC contexts, to inform the development of intentional and validated indicators for measuring and addressing cancer inequities.