Urinary Titin as a Non-Invasive Biomarker for Sarcopenia Sex Differences in Unresectable Digestive Malignancies: A Retrospective Cohort Study.

The prognosis of sarcopenia is poor in cancer patients. Recently, urinary titin, a biomarker of muscle damage, has been suggested as a potential marker for sarcopenia. However, its utility in patients with unresectable digestive malignancies remains unclear. In addition, sex differences have been reported in the association between sarcopenia and urinary titin levels. This study aimed to evaluate urinary titin as a diagnostic marker for unresectable digestive malignancies, focusing on sex differences. This retrospective study enrolled 96 patients (58 males, 38 females; median age 70), and urinary titin was evaluated as a diagnostic biomarker in relation to clinical factors (e.g., age, Eastern Cooperative Oncology Group performance status [ECOG PS], albumin [Alb]) and muscle indicators (e.g., psoas muscle index [PMI], handgrip strength). In male patients, urinary titin levels were significantly higher in the sarcopenia subgroup (5.78 vs. 2.79 pmol/mgCr, = 0.008), and multivariate analyses identified urinary titin as an independent predictor of sarcopenia (odds ratio 13.4, = 0.028). The receiver operating characteristic (ROC) analysis demonstrated fair diagnostic performance (area under the curve [AUC] 0.729), with an optimal cutoff value of 3.676 pmol/mgCr. Urinary titin may serve as a useful non-invasive diagnostic biomarker for sarcopenia in patients with unresectable digestive malignancies, particularly in males. These findings suggest that sex-specific approaches are required for sarcopenia assessment with urinary titin.