Background: Obstructive sleep apnea (OSA) is associated with increased cardiovascular risk, particularly through right ventricular (RV) dysfunction. Cancer antigen 125 (CA125), a biomarker traditionally used in ovarian cancer, has shown potential as an indicator of RV dysfunction. This study aims to compare CA125 levels between OSA patients and controls and to evaluate its association with disease severity and subclinical RV dysfunction.

Methods: This cross-sectional study included sixty OSA patients, divided into severe (apnea-hypopnea index [AHI] ≥ 30) and non-severe groups, and sixty age- and sex-matched controls. Cancer antigen 125 levels were assessed together with echocardiographic markers. Regression analysis identified predictors of severe OSA, and receiver operating characteristic (ROC) analysis assessed the diagnostic performance of CA125.

Results: Cancer antigen 125 levels were significantly elevated in severe OSA patients compared to non-severe and control groups (median 34.3 vs. 12.9 vs. 10.3 U/mL, P < .001). Cancer antigen 125 correlated with RV fractional area change (RV-FAC) (r = −0.496, P < .001), tricuspid annular plane systolic excursion (TAPSE) (r = −0.285, P = .027), and AHI (r = 0.581, P < .001). Regression analysis identified CA125 (odds ratio [OR] = 1.259, 95% con-fidence interval [CI]: 1.102-1.438, P = .001) and TAPSE (OR= 0.425, 95% CI: 0.217-0.834, P = .013) as independent predictors of severe OSA. ROC analysis showed that CA125 could effectively predict RV dysfunction (area under the curve [AUC] = 0.857) and severe OSA (AUC = 0.804).

Conclusion: Elevated CA125 levels are associated with increased disease severity and subclinical RV dysfunction in OSA, suggesting its potential as a biomarker for early cardiac involvement.