Volumetric-modulated arc stereotactic radiotherapy for intramedullary cervical spinal cord metastases: Report of two cases

The treatment results of intensity-modulated stereotactic radiotherapy (IM-SRT) by volumetric-modulated arc therapy (VMAT) for intramedullary cervical spinal cord metastases (IMCSCM) in two cases were presented. Case 1: A 76-year-old woman showed left-sided motor weakness and left arm pain and dysesthesia due to IMCSCM at C [cervical] 6-7 (located a little to the left laterally) with multiple small brain metastases from thyroid carcinoma.  Multiple brain metastases were successfully treated by stereotactic radiosurgery (SRS). In addition, IMCSCM was treated by IM-SRT. Case 2: A 48-year-old man presented with asymptomatic IMCSCM at C2 (located a little to the right laterally) after conventional whole brain radiotherapy (WBRT) and multiple sessions of SRS/SRT for multiple brain metastases from lung adenocarcinoma. IMCSCM was treated by IM-SRT. In both cases 39 Gy in 13 fractions (without PTV [planning target volume] margin, D95%=95% dose) was delivered to the IMCSCM (0.3 ml and 0.5 ml in volume respectively) by coplanar 2-full circular arc VMAT. The maximum dose to the tumor was 46.3 Gy in case 1 and 47.1 Gy in case 2. IMCSCM in both cases shrank markedly without adverse effects during the follow-up period of 32 months and 8 months respectively. The symptoms of the extremities in case 1 were subsided completely until the patient’s death at 34 months after SRT from lung metastasis. In case 1 IMCSCM had been thought to be a relatively radioresistant thyroid carcinoma metastasis. In case 2 IMCSCM was near the field of the prior WBRT. However, both tumors were successfully treated without adverse effects by VMAT IM-SRT.