The relationship between psoas muscle index and surgical/oncological outcomes in prostate cancer patients undergoing radical prostatectomy: a retrospective single-center study

Background: This study aimed to investigate the association between preoperative psoas muscle index (PMI), surgical and oncological outcomes, and the requirement for adjuvant radiotherapy (ART) in patients with prostate cancer (PCa) undergoing radical prostatectomy (RP). Methods: Fifty-eight patients who underwent RP for localized PCa between January 2021 and August 2024 were retrospectively evaluated. Demographic, clinical, and pathological characteristics, as well as preoperative PMI values, were recorded. The relationships between PMI, ART requirement, and pathological findings were analyzed. Additionally, the predictive performance of PMI for ART was assessed using Receiver Operating Characteristic (ROC) curve analysis. Results: The mean age of patients was 65.34 ± 6.63 years, and the mean PMI was 6.12 ± 1.44 cm2/m2. ART was required in 31% of patients. The ART group had significantly lower PMI values (5.32 ± 1.57 vs. 6.48 ± 1.24 cm2/m2; p = 0.01). Total Prostate Spesific Antigen (PSA) and PSA density were also significantly higher in the ART group (p = 0.002 and p = 0.001, respectively). Patients with pathological stage ≥T3 and those with extraprostatic extension had significantly lower PMI values (p = 0.01 and p = 0.04, respectively). ROC analysis identified a cut-off value of 5.91 cm2/m2 for PMI, with 68% sensitivity and 72%specificity (Area Under the Curve (AUC): 0.712; 95% Confidence Interval (CI): 0.560–0.865; p = 0.01). In multivariate analysis, lower PMI (Odds Ratio (OR) = 0.48, p = 0.027) and pathological T stage ≥T3 (OR = 12.85, p = 0.014) independently predicted the need for ART. Conclusions: In patients undergoing RP, lower PMI was associated with adverse pathological features and ART requirement. Preoperative PMI assessment, when combined with PSA and PSA density, may provide additional value in predicting aggressive tumor behavior. Validation through larger, multicenter, prospective studies is warranted.

Adjuvant radiotherapy; Prostate cancer; Psoas muscle index

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