Serum Palmitoleic Acid and Arachidonic Acid as a Noninvasive Screening Tool for Endometrial Cancer

Background/Objectives: Endometrial cancer (EC) is the most prevalent gynecological malignancy in developed countries, yet no clinically validated noninvasive screening biomarker exists. Fatty acid metabolic reprogramming is a hallmark of cancer that produces measurable changes in systemic free fatty acid (FFA) profiles. We aimed to identify serum FFAs altered in EC and evaluate their potential as early diagnostic biomarkers. Methods: Gene expression of fatty acid metabolic enzymes in EC tissues was assessed using public databases. Serum levels of 19 FFAs were quantified by gas chromatography–mass spectrometry in 72 patients with EC and 84 healthy donors. A two-variable diagnostic model was constructed using logistic regression and validated in an independent dataset. Results: Multiple fatty acid metabolic enzymes involved in de novo synthesis were upregulated in EC tissues as early as stage I, while enzymes mediating fatty acid uptake and release were downregulated. Serum levels of palmitoleic acid, oleic acid and dihomo-γ-linolenic acid were significantly elevated, whereas arachidic acid and arachidonic acid were significantly decreased in patients with EC from stage I onward. A diagnostic model combining palmitoleic acid and arachidonic acid achieved an area under the receiver operating characteristic curve of 0.9674, with a sensitivity of 91.3% and specificity of 96.4% in the validation dataset, including for stage I disease, and was independent of body mass index, age, metastasis status, and family history. Conclusions: Serum FFA profiling represents a promising noninvasive strategy for early EC detection, with the potential to complement existing diagnostic methods.