Background <p>This study develops a Quality of Care Index (QCI) to evaluate global disparities in care quality for five head and neck cancer (HNC) subtypes—thyroid, larynx, lip and oral cavity, nasopharynx, and other pharynx cancers—from 1990 to 2021, addressing the issue of existing indicators not fully reflecting cancer quality.</p> Methods <p>We developed a QCI for five HNC subtypes using data from the Global Burden of Disease Study 1990–2021. The QCI was constructed through principal component analysis of six epidemiological indicators. Trends in age-standardized DALY rates (ASDR) and QCI were assessed globally, regionally, nationally and by Socio-demographic Index (SDI).</p> Results <p>From 1990 to 2021, ASDR declined markedly for larynx and nasopharynx cancers, whereas thyroid, lip and oral cancer, and other pharynx cancers decreased only in high-SDI regions, remaining stable or rising in low- and middle-SDI regions. QCI improved for all subtypes. High-SDI regions consistently exhibited a ‘high-quality, low-burden’ pattern, with the highest absolute QCI values but limited relative gains; low-SDI regions, in contrast, faced “high burden and low quality” and, despite lower absolute QCI, showed the largest improvements over time. Subtype-specific patterns were evident: nasopharynx cancer achieved the greatest QCI gains, larynx cancer showed consistent ASDR decline and QCI improvement across all SDI levels, and thyroid cancer improved in QCI despite ASDR increases in low- to middle- SDI regions. Lip and oral cancer, and other pharynx cancers exhibited persistent high burden in lower SDI regions, with modest QCI gains.</p> Conclusions <p>Global HNC care quality has improved, but reductions in disease burden and gains in QCI were not fully aligned. Substantial inequalities persist across cancer subtypes and SDI regions. Strengthening care infrastructure and optimizing HNC management in resource-limited settings are needed to reduce disparities.</p>