Clinical utility of serum procalcitonin for suspected sepsis in patients with cancer: A prospective observational study

ABSTRACT Background: Clinical utility of a single serum procalcitonin (PCT) measurement in patients with cancer presenting with a suspected infection episode remains uncertain. Objectives: The primary objective was to evaluate the diagnostic performance of PCT for bloodstream infection (BSI) and sepsis in patients with cancer. The secondary objective was to assess its ability to predict 14-day all-cause mortality. Materials and Methods: In this prospective observational study (May–July 2025), suspected infection episodes were defined as events in which blood cultures and serum PCT (ng/mL) were obtained, and antibiotics were initiated or escalated. Outcomes included BSI (positive blood culture for a pathogenic organism), probable sepsis (Δ sequential organ failure assessment [SOFA] score ≥2 with negative blood culture), and confirmed sepsis (Δ SOFA ≥2 with positive blood culture). Results: A total of 543 suspected infection episodes were identified in 468 patients. At a PCT cutoff of 0.5 ng/mL, sensitivity for BSI was 88.3% overall, 89.8% among patients already receiving antibiotics, and 83.3% in patients with neutropenia. At a cutoff of 30 ng/mL, specificity for BSI approached 90% across all groups. Receiver operating characteristic analysis demonstrated poor overall discrimination area under the receiver operating characteristic curve (AUC <0.7). On logistic regression analysis, PCT was not an independent predictor of 14-day all-cause mortality (odds ratio: 1.01; P, 0.132). Conclusion: While overall diagnostic performance of PCT was limited, extreme values (<0.5 ng/mL and >30 ng/mL) demonstrated clinically useful sensitivity and specificity for identifying BSI and confirmed bacterial sepsis in patients with cancer, including those with neutropenia.