Cancer history and creatinine-cystatin C eGFR discordance across three Chinese health-examination centers

Creatinine- and cystatin C-based estimates of glomerular filtration rate (eGFR) may differ because the two markers are affected by different non-GFR factors. Whether a history of cancer is associated with clinically relevant negative eGFR discordance among adults attending routine health examinations remains unclear. This three-center cross-sectional study included adults aged 18 years or older who underwent single-visit health examinations with linked questionnaire data in Chongqing, Shandong, and Jiangsu, China, from January through July 2026. The analytic cohort was restricted to participants with both creatinine and cystatin C measurements, ascertainable cancer-history status, complete prespecified covariates, plausible laboratory values, and creatinine-based eGFR (eGFRcr) > = 60 mL/min/1.73 m2. eGFR based on creatinine (eGFRcr), cystatin C (eGFRcys), and both markers (eGFRcr-cys) was recalculated from the original measurements. Large negative discordance, the primary outcome, was defined as eGFRcys at least 30% lower than eGFRcr. Prevalence ratios (PRs) were estimated with modified Poisson regression and robust variance. Center-specific and pooled analyses, alternative discordance definitions, continuous differences, GFR-category migration, subgroups, overlap weighting, and an age-spline sensitivity analysis were examined. Among 3491 participants, 257 (7.36%) reported a physician-diagnosed cancer history. Large negative discordance occurred in 14.79% of participants with cancer history and 4.79% of those without cancer history ( P < 0.001). In the fully adjusted pooled model, cancer history was associated with a higher prevalence of large negative discordance (PR, 1.53; 95% CI, 1.08–2.17; P = 0.018). The corresponding PR was 1.22 (95% CI, 0.78–1.89; P = 0.383) in Chongqing and Shandong combined and 2.40 (95% CI, 1.37–4.18; P = 0.002) in Jiangsu; the center-by-cancer-history interaction was not significant ( P = 0.212). Cancer history was also associated with a 2.73-percentage-point lower adjusted relative eGFR difference (95% CI, -4.46 to -1.00; P = 0.002). Similar patterns were seen with a 20% relative-discordance threshold and an absolute eGFR difference of -15 mL/min/1.73 m2. Crude downward GFR-category migration was substantially attenuated after multivariable adjustment. Among adults with eGFRcr > = 60 mL/min/1.73 m2 attending routine health examinations at three Chinese centers, cancer history was associated with greater negative discordance between cystatin C- and creatinine-based eGFR in the pooled adjusted analysis. Estimates varied across centers, and a nonsignificant center-by-cancer-history interaction should not be interpreted as evidence of equivalent effects. Alternative discordance measures were broadly similar, whereas overlap-weighted and adjusted category-migration analyses were less precise or null. When kidney-function estimates are clinically consequential in adults with a cancer history, reliance on a single filtration marker should therefore be cautious; these data do not establish impaired kidney function or identify which eGFR estimate is closest to measured GFR.