Radiotherapy for oligometastatic disease in patients with spinal cord compression (MSCC) from relatively radioresistant tumors

Background: Radiotherapy alone is the most common treatment for metastatic spinal cord compression (MSCC). Patients with relatively radioresistant tumors and oligometastatic disease may benefit from more intensive therapies (surgery, high-precision radiotherapy). If such therapies are not available, one can speculate whether patients benefit from dose escalation beyond the standard regimen 30 Gy in ten fractions. Patientsand Methods: Of 206 patients with MSCC from relatively radioresistant tumors (renal cell carcinoma, colorectal cancer, malignant melanoma), 51 had oligometastatic disease (no visceral or other bone metastases, involvement of only one to three vertebrae). In this subset, 21 patients receiving 30 Gy in ten fractions were retrospectively compared to 30 patients receiving higher doses. Seven further potential prognostic factors were investigated: age, gender, tumor type, performance status, interval from tumor diagnosis to radiotherapy of MSCC, pretreatment ambulatory status, and time developing motor deficits before radiotherapy. Results: Motor function improved in 52% of patients after 30 Gy and 40% after higher doses (p - 0.44). On multivariate analysis, functional outcome was associated with interval from tumor diagnosis to radiotherapy (p - 0.020). 1-year local control rates were 84% after 30 Gy and 82% after higher doses (p - 0.75). No factor was associated with local control. 1-year survival rates were 76% after 30 Gy and 63% after higher doses (p - 0.52). On multivariate analysis, survival was associated with performance status (p - 0.022) and interval from tumor diagnosis to radiotherapy (p - 0.039), and almost with pretreatment ambulatory status (p-0.069). Conclusion: Dose escalation beyond 30 Gy in ten fractions did not improve motor function, local control, and survival in MSCC patients with oligometastatic disease from relatively radioresistant tumors.