• Efficacy - evaluated by the response rate, based on mobility score using the Tomita scale. An improvement in mobility or stable mobility score will be regarded as a response. [ Time Frame: Pre-reirradiation status, 1 week, 5 weeks, 3 months and every 3 months until death ] [ Designated as safety issue: No ]
  

• Quality of life - assessed by the EORTC QLQ-C15 PAL version 1.0 [ Time Frame: Pre-reirradiation status, 1 week, 5 weeks, 3 months and every 3 months until death ] [ Designated as safety issue: No ]
  
• Non-spinal radiation-induced toxicity - assessed using standard RTOG criteria [ Time Frame: 1 week, 5 weeks, 3 months and every 3 months until death ] [ Designated as safety issue: Yes ]
  
• Rate of long-term spinal toxicity - assessed using RTOG SOMA morbidity grading system. [ Time Frame: From clinical detection (usually 9 - 15 months post irradiation) ] [ Designated as safety issue: Yes ]
  

The occurrence of Malignant Spinal Cord Compression (MSCC) in a previously irradiated area of spinal cord is a common clinical situation in oncology. Only a minority of patients are amenable to non-radiotherapy management i.e, decompression spinal surgery. Therefore, re-irradiation is often considered as the unique therapeutic option for these patients.

The re-irradiation schedule for eligible patients will be in line with in-house guidelines on cumulative Biologically Effective Dose (BED) ie., ≤100 Gy2 (<6 months since most recent RT) or ≤130 Gy2 (>6 months since most recent RT). Adherence to these guidelines ensures that the cumulative dose delivered to eligible patients carries a low or intermediate risk only, for development of radiation-induced myelopathy (RIM). The re-irradiation schedule delivered will ensure that the patient receives at least the lowest dose equivalent known to have demonstrated efficacy in MSCC, and will deliver 3Gy per fraction. The re-irradiation schedule will be determined according to two parameters : -

• The interval since the last course of radiotherapy to the involved area of spinal cord
• The dose received to date - using BED conversion

All patients with progressive or new neurological symptoms will have an MRI of the spine performed, which is the gold standard for imaging spinal cord. Tumour progression or recurrence is a major deferential diagnosis. All MRI's will be reviewed by a consultant radiologist. All cases with RTOG SOMA score 2+ will be handled as a serious adverse event. A review of the incidence of RTOG SOMA grade 2+ will be conducted following 14 evaluable patients: if the overall rate of RIM observed exceeds the rate reported by Nieder et al (i.e., 3% for low risk patients, 25% for intermediate risk patients) by one patient - the trial will stop.

All patients will be prescribed high-dose corticosteroids (Dexamethasone), commencing with 8mg tds and tapered according to patient response. A proton-pump inhibitor may also be prescribed, in line with current practice. All patients receiving treatment to fields below the level of T9 will receive ondansetron (Zofran) 8mg p.o. prophylactically as an anti-emetic, as per current practice.