Spleen Shrinkage Predicts Dangerous Blood Count Drops After Peptide Radionuclide Therapy

A 30% decline in spleen volume at 12 months post-177Lu-DOTATATE treatment predicted leukopenia at 24 months with AUC 0.91, sensitivity 93%, and specificity 90%. White blood cell counts and relative spleen volume reduction were also independent predictors, but spleen volume reduction was far superior. Automated splenic volume assessment outperformed all conventional laboratory parameters.

Retrospective analysis of 88 patients with metastatic neuroendocrine tumors treated with 177Lu-DOTATATE from February 2009 to July 2021. Inclusion: ≥4 treatment cycles, ≥24 months follow-up, tumor uptake ≥ liver on baseline receptor imaging. Blood counts and imaging data analyzed for predictive markers of radiation-induced leukopenia.

Leukopenia (low white blood cells) after PRRT is a serious complication that increases infection risk and may force treatment discontinuation. Currently, clinicians rely on blood tests that detect the problem only after it's developing. Spleen volume — measurable on routine CT scans already being performed for tumor monitoring — provides much earlier warning, allowing proactive management.

PRRT is expanding as a treatment option for neuroendocrine tumors, and managing hematotoxicity is crucial for patient safety. Finding an imaging-based biomarker that outperforms blood tests is particularly valuable because these CT scans are already routinely performed — no additional testing is needed, just automated measurement of an organ already visible on the scan.

Retrospective single-center study with moderate sample size. Exclusion of patients with <24 months follow-up and <4 treatment cycles may introduce survival bias. The optimal timing for spleen volume assessment and the generalizability to different treatment protocols need prospective validation. Automated splenic volumetry requires appropriate software.