A novel risk stratification for predicting prognosis of colorectal cancer patients with bone metastasis

Background Our understanding in prognosis of bone metastasis (BM) from colorectal cancer (CRC) is limited. We aimed to establish a clinical risk stratification for individually predicting the survival of CRC patients with BM. Methods A total of 200 CRC patients with BM were included in this study. Survival time from BM diagnosis was estimated using the Kaplan-Meier method. The multivariable COX regression model identified the risk factors on cancer specific survival (CSS). Based on weighted scoring system, the stratification model was constructed to classify patients with BM according to prognostic risk. Discrimination power and calibration ability of risk stratification were measured. Results The median CSS time was 11 months after BM diagnosis. Lymph node metastasis, Carbohydrate antigen 199 (CA199) levels, bone involvement, Karnofsky Performance Status (KPS) scores, primary tumor resection, bisphosphonates therapy and radiotherapy were identified as predictors of CSS. Four risk groups were stratified according to weighted scoring system, including low risk, medium risk, medium-high risk and high risk group, with 35, 16, 9 and 5 months of median CSS, respectively (P=0.000). The risk stratification displayed good accuracy in predicting CSS, with acceptable discrimination and calibration. Conclusions This novel risk stratification predicts CSS in CRC patient with BM using easily accessible clinicopathologic factors, which is recommended for use in individualized clinical decision making in patient with BM.