Serum Galectin-1 as a Diagnostic Biomarker in Endometriosis: A Prospective Longitudinal Study

Endometriosis is a chronic condition characterized by the presence of endometrial-like tissue outside the uterine cavity. It affects ~10% of reproductive-aged individuals and is associated with dysmenorrhea and infertility. Although imaging modalities have improved diagnosis, laparoscopy is required in many cases, contributing to 4-11 years of diagnostic delay. Non-invasive biomarkers could improve diagnosis and clinical decision-making, yet no candidate has achieved sufficient accuracy for routine use. Galectins, a family of β-galactoside-binding lectins involved in angiogenesis, immune regulation, and fibrosis, have emerged as promising biomarkers. In this study, we measured serum Galectin-1 (Gal-1) concentrations in 80 women with endometriosis and 15 controls using ELISA at four time points. Preoperative Gal-1 levels were significantly higher in endometriosis patients, particularly in Stage III-IV disease. ROC analysis yielded a modest diagnostic performance (AUC 0.692; <i>p</i> = 0.011) with high sensitivity (91.3%) and excellent negative predictive value (96.8%) but low specificity (46.7%) at a study-derived threshold (>14.06 ng/mL). Longitudinally, Gal-1 levels decreased immediately after surgery and rose above baseline by one year, while no significant correlations with preoperative pain severity were observed. These findings suggest that serum Gal-1 alone is insufficient as a diagnostic test but may be useful for multi-marker strategies to improve early diagnosis.