Serum Trace Elements and Self-Reported Physician-Diagnosed Tumor History: A Secondary Cross-Sectional Analysis of the Exposure Study on Susceptible People (SPES).

Background and Objectives: SPES was a 2016-2017 regional biomonitoring program. We conducted a secondary cross-sectional analysis of associations between current serum trace-element distributions and heterogeneous, self-reported physician-diagnosed tumor history, rather than registry-confirmed or incident cancer. Materials and Methods: Among 4137 questionnaire responders, 86 reported a tumor history. Mixed-effects logistic models for 20 channels were adjusted for age, sex, smoking, and geographic cluster and pooled across 30 completed datasets. Benjamini-Hochberg FDR control was applied across 20 primary comparisons. Results: Higher Cr-52 was associated with lower prevalence odds of reported history (odds ratio per one-standard-deviation increase in log concentration, 0.751; 95% confidence interval, 0.601-0.937; p = 0.011; q = 0.226), but no channel met q < 0.05. Cr-52 was below the limit of quantification in 45/86 (52.3%) participants with reported history and 1646/4048 (40.7%) without. The inverse direction persisted in non-independent complementary analyses; none met the applicable FDR threshold. Conclusions: No channel met the FDR criterion. The Cr-52 pattern was nominal and exploratory. These prevalence associations with a heterogeneous, unvalidated self-reported outcome do not establish temporality, causality, chromium speciation, or a protective effect.