Eric Lis MD, Presenter: Nothing to Disclose

George S. Krol MD, Abstract Co-Author: Nothing to Disclose

Single fraction intensity modulated radiation therapy (IMRT) is a relatively new technique which allows for tumoricidal doses of radiation to be delivered to traditionally radio-resistant cancers while sparing critical adjacent structures. The purpose of this investigation is to assess the risk of vertebral fracture following IMRT for spinal metastases. 

Baseline and post treatment CT/radiographic studies of 62 patients who underwnt single fraction IMRT for metastatic spinal lesions were reviewed for findings of fracture/vertebral compression.  Treatment dose ranged from 1800-2500 cGy (mean 2300).

Twenty patients had baseline endplate or mild compression fractures. Following treatment, 27 patients (39%) had new or progressive fractures. Lytic metastases (p=0.04), thoracolumbar or lumbar location (p=0.04), and percent vertebral body involvement (p=0.02) correlated with increased fracture risk. Obesity, posterior element involvement, and local kyphosis did not confer increased risk. Pretreatment endplate fracture or mild compression did not correlate with new fracture development or progression. Fracture progression led to surgery (n=2), kyphoplasty (n=1), or significant pain (n=9) in 12 patients. Although difficult to ascertain with certainty, the majority of fractures did not appear to result from disease progression.

Vertebral fracture is common following single fraction IMRT for metastatic lesions of the spine especially lytic lesion with more than 40% vertebral body involvement

The study suggests that there is relatively high risk of developing fractures after single fraction RT and earlier profilactic therapy (like vertebral cement augmentation) may be beneficial. 

Lis, E, Krol, G, Risk Factors and Incidence of Vertebral Fracture Following Single Fraction Intensity Modulated Radiation Therapy for Spinal Metastases.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6022699.html