New Approach for Treatment of Vertebral Metastases Using Intensity-Modulated Radiotherapy

Purpose: To perform aggressive radiotherapy for vertebral metastases. Using very steep dose gradients from intensity-modulated radiotherapy (IMRT), a protocol based on the concept of partial volume dose to the spinal cord was evaluated. Patients and Methods: 50 patients with vertebral metastases were treated using IMRT. In previously unirradiated cases, where a prescribed dose of 80 Gy (BED(10)) was delivered, the constraint to the spinal cord should be less than 100 Gy (BED(2)). For previously irradiated cases, on the other hand, the dose is the same as in the previously unirradiated case; however, constraints for the spinal cord are a cumulative BED(2) of less than 150 Gy, BED(2) of less than 100 Gy in each instance, and a treatment gap of more than 6 months. There were 6 patients considered for a partial volume dose to the spinal. cord. They all received higher BED(2), ranging from 51-157 Gy of D(1cc). Results: Among the 24 patients who survived longer than 1 year, there was 1 case of transient radiation myelitis. There were no other cases of spinal cord sequelae. Conclusions: Based on the present results, we recommend a BED(2) of 100 Gy or less at D(1cc) as a constraint for the spinal cord in previously unirradiated cases, and a cumulative BED(2) of 150 Gy or less at D(1cc) in previously irradiated cases, when the interval was not shorter than 6 months and the BED(2) for each session was 100 Gy or less. The prescribed BED(10) of 80 Gy could be safely delivered to the vertebral lesions.