Intensity Modulated Radiotherapy on Osteolytic Spinal Metastasis of Colorectal Cancer: Stability, Survival Analysis and Impact of K-RAS Mutation

Background: The aim of this study was to evaluate the impact of intensity-
modulated radiotherapy in terms of spinal stability as well as survival and 
related prognostic factors in colorectal cancer with bone metastases.
Methods: A prospective multi-center analysis of fifty-nine patients with 
colorectal cancer and spinal bone metastases were treated in the period from 
April 2019 and June 2022. The stability was assessed by using the Taneichi 
score before, 3, and 6 months after radiotherapy. Additionally, prognostic 
factors for stability and overall survival were assessed.
Results: Before radiotherapy 71.2% of patients were unstable and 6 months 
after RT 60% of pts were stable. After 6 months, only 10% (n=3) of the 
originally unstable spinal bone metastasis patients were reclassified as stable. 
So predictive factors for stability couldn’t be assessed. Mean bone survival in 
our study was 7.49 (95% CI 6.29-8.68). Four characteristics had a significant 
impact on survival in univariate analysis: kps>70, bisphosphonate, 
chemotherapy therapy, and gene mutation and extraosseous metastases 
(p<0.001).
Conclusions: Intensity modulated radiotherapy is associated with poor stability 
of osteolytic spinal metastases from colorectal cancer. Survival in patients with 
bone metastases from colorectal cancer remains poor. Performance state, 
chemotherapy, bisphosphonate, and gene mutation be a predictor for the 
response, with no difference regarding survival and stability from conformal 3D 
radiotherapy.