A scoring system to predict local progression-free survival in patients irradiated with 20 Gy in 5 fractions for malignant spinal cord compression

BACKGROUND: Local progression-free survival (LPFS = stable or improved motor function/resolution of paraplegia during RT without in-field recurrence following RT) is important when treating metastatic spinal cord compression (MSCC). An instrument to estimate LPFS was created to identify patients appropriately treated with short-course RT instead of longer-course RT plus/minus decompressive surgery. METHODS: In 686 patients treated with 20 Gy in 5 fractions alone, ten characteristics were retrospectively analyzed for LPFS including age, interval between tumor diagnosis and RT of MSCC, visceral metastases, other bone metastases, primary tumor type, gender, time developing motor deficits, pre-RT gait function, number of vertebrae affected by MSCC, and performance score. Characteristics significantly (p < 0.05) associated with LPFS on multivariate analyses were incorporated in the scoring system. Six-month LPFS rates for significant characteristics were divided by 10, and corresponding points were added. RESULTS: On multivariate analyses, visceral metastases (p < 0.001), tumor type (p = 0.009), time developing motor deficits (p < 0.001) and performance score (p = 0.009) were associated with LPFS and used for the scoring system. Scores for patients ranged between 24 and 35 points. Three groups were designed: 24–28 (A), 29–31 (B) and 32–35 (C) points. Six-month LPFS rates were 46, 69 and 92%, 12-month LPFS rates 46, 63 and 83%. Median survival times were 2 months (61% died within 2 months), 4 months and ≥ 11 months (median not reached). CONCLUSIONS: Most group A patients appeared sub-optimally treated with 20 Gy in 5 fractions. Patients with survival prognoses ≤2 months may be considered for best supportive care or single-fraction RT, those with prognoses ≥3 months for longer-course RT plus/minus upfront decompressive surgery. Many group B and most group C patients achieved long-time LPFS and appeared sufficiently treated with 20 Gy in 5 fractions. However, based on previous data, long-term survivors may benefit from longer-course RT.