Stereotactic radiotherapy for spinal intradural metastases developing within or adjacent to the previous irradiation field--report of three cases

Abstract

Results of stereotactic radiotherapy (SRT) for spinal intradural metastases developing inside or adjacent to the previous external-beam radiation therapy (EBRT) field are shown in 3 cases. One case of spinal intramedullary metastasis and two cases of intradural extramedullary metastases were treated using a Novalis shaped-beam SRT. Case 1 developed an intramedullary metastatic tumor in the C1 spinal medulla inside the previous whole brain EBRT field and another lesion adjacent to the field in the C2 spinal medulla. Case 2 developed intradural extramedullary metastasis around C6-8 inside the previous EBRT field for the primary lung adenocarcinoma. Case 3 developed multiple spinal intradural extramedullary metastatic deposits after surgical resection and following whole brain EBRT for brain metastasis. We delivered 24 to 36 Gy in 5 to 12 fractions. The treated tumors were stable or decreased in size until the patients' death from the primary cancer (10, 22, and 5 months). Neurological symptoms were stable or improved in all 3 patients. Palliative SRT using Novalis is expected to be safe and effective even if the patient develops spinal intradural metastases within or adjacent to the previous irradiation field.

Fig. 1

Two types of shells for patient fixation during Novalis stereotactic radiation therapy (SRT). One is for cervical spinal lesions (A) and the other for thoracic, lumbar, and sacral lesions (B).

Fig. 2

Case 1. Coronal view (A) and sagittal view (B) of CT with contrast enhancement during treatment plan of Novalis SRT for C1 and C2 intramedullary metastases on BrainSCAN (BrainLAB, Tokyo, Japan). Sagittal views of MRI before (C) and 4 months after SRT (D). The treated lesions were stable for 10 months after SRT until the patient died from primary lung adenocarcinoma.

Fig. 3

Case 2. Sagittal MRI before (A) and after (B) the second surgical resection of recurrent intradural extramedullary metastasis around C6-8. Coronal view (C) and sagittal view (D) of MRI with gadolinium (Gd) enhancement during treatment plan of Novalis SRT for residual tumor on the surface of the spinal medulla. The tumor almost disappeared within 3 months after SRT (E) and no relapse occurred prior to the patient’s death 22 months after SRT.

Fig. 4

Case 3. Coronal (A) and sagittal (B) view of treatment planning of SRT on CT. The tumor around C1-2 (C: sagittal MRI with gadolinium enhancement before SRT) disappeared within 3 months after the treatment (D, sagittal MRI with Gd enhancement). No relapse occurred prior to the patient’s death from primary cancer 5 months after the Novalis treatment.

Fig. 5

Case 3. Coronal (A) and sagittal (B) view of treatment planning of SRT on CT. The tumor around L1 (C: sagittal MRI with Gd enhancement before SRT) was decreased in size within 8 months after SRT (D, sagittal MRI with Gd enhancement).