Bone metastases (BM) from colorectal cancer (CRC) are often accompanied by extraosseous metastases and have a dismal prognosis. The present study aims to find out the risk factors for BM in metastatic CRC (mCRC) and the prognostic factors for CRC patients with BM.
The study was based on a training cohort of 214 mCRC patients (of which 101 patients with BM) from our center, and a validation cohort of 511 mCRC patients from another institution (of which 173 patients with BM). The risk and prognostic nomogram for BM were identified using univariate and multivariate analyses. The goodness of fit, discrimination and calibration performance of the nomograms were assessed by R2, concordance statistics (C-statistics) and the calibration curve. The results were internally validated using bootstrap resampling in the training cohort and externally validated in the validation cohort.
The novel BM risk nomogram comprised of seven variables (degree of tumor differentiation, N_stage, serum ALP, LDH, CEA, liver metastasis and lung metastasis). It showed good performance with an R2 of 0.447 and a C-statistics of 0.846 (95% CI, 0.793 to 0.898) in the training cohort, and an R2 of 0.325 and a C-statistics of 0.792 (95% CI, 0.750 to 0.834) in the validation cohort. The optimal cutoff value to identify individuals at low or high risk was 56% probability with the sensitivity of 71.3% and specificity of 89.4%. The prognostic nomogram included five factors (tumor differentiation, No. of extra-BM organs, No. of BM lesions, ALP and LDH) with an R2 of 0.284 and a C-statistics of 0.723 (95% CI, 0.657 to 0.789) in the training set. This nomogram was externally validated in the validation cohort with an R2 of 0.182 and a C-statistics of 0.682 (95% CI, 0.638 to 0.726).
The developed and validated risk nomogram and prognostic nomogram show good performance on predicting the occurrence of BM in mCRC and prognosis in CRC patients suffered from BM. The risk nomogram can be used as a cost-effective preliminary screening tool prior to bone scan.
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Has not received any funding.
The author has declared no conflicts of interest.