Perioperative Dynamics of Tumor Cells into the Circulatory System During Vertebral Cement Augmentation in Metastatic Spinal Disease—A Prospective Pilot Study

Background/Objectives: Vertebroplasty (VP) and balloon kyphoplasty (KP) are well-established surgical interventions used to stabilize pathological fractures and severe spinal instability resulting from osteolytic spinal metastases. Both procedures increase intravertebral pressure, which may elevate the risk of hematogenous dissemination of tumor cells. However, data on circulating tumor cells (CTCs) in the perioperative setting remain limited. Methods: This prospective, single-center exploratory pilot study included 11 patients undergoing VP or KP for spinal metastases (breast cancer, n = 7; prostate cancer, n = 3; colon cancer, n = 1). Peripheral blood samples were collected preoperatively and at 1, 5, 10, and 20 min after cement injection and analyzed for CTC-associated, tumor-specific mRNA markers (AdnaTest®) using marker panels corresponding to each patient’s primary cancer type. Vertebral biopsies obtained prior to cement injection confirmed tumor infiltration of the treated levels. Results: In all patients with histopathologically confirmed tumor presence (9/10; 90%), one or more CTC-associated mRNA markers were detectable at one or more time points, most consistently at 5 and 10 min after cement injection, whereas the biopsy-negative patient showed no marker signal. In an exploratory analysis of the four patients with baseline GA733-2 positivity (three breast cancer and one colon cancer case), a 3.8-fold increase in marker levels was observed 5 min post-injection (nominal p = 0.026, 95% CI: 1.4–10.4; not adjusted for multiple comparisons); this effect was not sustained at 10 or 20 min. No significant correlation was found between cement volume, baseline marker levels, or vertebral location (thoracic vs. lumbar). Conclusions: In this pilot study, CTC-associated mRNA markers were detectable in peripheral blood during VP and KP, and marker positivity was concordant with the histopathological findings of the treated vertebra in this small cohort. The transient increase of a single marker in a small subgroup is hypothesis-generating and does not demonstrate the release of viable tumor cells. Whether perioperative strategies to limit tumor cell release are warranted needs to be evaluated in larger, controlled studies.