Predominance of Spinal Metastases Involving the Posterior Vertebral Body.

BACKGROUND

Spinal metastases pose significant morbidity. For many histologies, the spine is a frequent site for bone metastases. This predilection is not fully understood, and there are conflicting reports regarding the distribution within the vertebral body itself. Knowing this distribution will give clues as to the underlying biologic reason for this increased incidence in the spine and lead to a better understanding of tumor dispersion and growth.

METHODS

We retrospectively examined magnetic resonance imaging scans of patients undergoing radiation to the spine from 2015 to 2017 for spinal metastases. The anatomical distribution of lesions was categorized. Lesions were sorted along the sagittal plane into 5 groups: anterior only, anterior + middle, middle only, posterior + middle, and posterior only. Lesions that covered all groups were discarded. χ and post-hoc analyses were used for statistical analyses.

RESULTS

Three hundred metastatic lesions were examined in 89 patients; 203 lesions were used for analysis. Sixty-five percent of all lesions were found in posterior only and posterior + middle aspects of the vertebral body (P < 0.0001). This localization was significant regardless of histology: lung (67%, P < 0.0001), kidney (66%, P < 0.0001), sarcoma (67%, P < 0.0001), prostate (63%, P = 0.01), and breast (63%, P = 0.01). This was consistent across thoracic (n = 96) and lumbar (n = 63) regions (72% and 64%, respectively, P < 0.0001).

CONCLUSIONS

Metastatic lesions of the thoracolumbar spine have a greater propensity to localize to the posterior aspect of the vertebral body. These data support the hypothesis that there may be differences within the vertebral body leading to differential tumor dispersion and growth.