Clinical score based on CGRP, PD-1, and PD-L1 for PICC-related bloodstream infections in breast cancer

Peripherally inserted central catheter (PICC)-related bloodstream infections (BSIs) are serious complications in breast cancer patients. Reliable early risk assessment remains limited. Female breast cancer patients (n = 384) receiving PICCs were retrospectively analyzed. Serum CGRP levels were measured by ELISA, while PD-1 and PD-L1 expression was quantified via qPCR. A 3-point BioScore was calculated by assigning one point per abnormal biomarker (CGRP < 42.817 pg/mL, PD-1 > 2.301, PD-L1 < 1.613). Patients were stratified into low (0), intermediate (1-2), or high (3) risk groups. The cohort was split into training (n = 269) and validation (n = 115) sets. BSIs occurred in 78 patients (20.3%). The BioScore demonstrated excellent discrimination (AUC 0.96 in training and 0.93 in validation) and good calibration (Hosmer-Lemeshow P = 0.797 and 0.875). BSI rates rose with BioScore category. While the BioScore was derived from biomarker values measured at the time of clinical suspicion for BSI, its strong discriminatory performance suggests potential for earlier application, such as at routine follow-ups, pending prospective validation. The BioScore demonstrated excellent internal discrimination and calibration in a retrospective, single-center cohort. Further external and prospective validation is necessary before clinical use.