Prognostic risk factors in patients with bone metastasis from colorectal cancer.

The morbidity of bone metastasis (BM) from colorectal cancer (CRC) is increasing more than ever; however, insufficient research on BM from CRC leads to reduced awareness of the issue. Therefore, the aim of this study was to evaluate the clinical features and prognostic risk factors of CRC patients with BM. Clinical data were retrospectively analyzed for a total of 242 CRC patients with BM. Of the 242 CRC patients with BM, 52 (21.5 %) had bone metastasis alone (BMA) and 190 (78.5 %) had both bone and visceral metastasis (BM&VM). The median survival time (MST) after the diagnosis of BM in all 242 patients was 15.6 months (95 % confidence interval [CI] 12.74-18.46 months). The MST of the BMA group was significantly longer than that of the BM&VM group (29.1 vs. 12.8 months, p = 0.003). Using a Cox proportional hazard model, we identified a high carcinoembryonic antigen (CEA) level and BMA as independent prognostic factors for CRC patients with BM. For the BMA group, the independent prognostic factors were elevated alkaline phosphatase (ALP) and perineural invasion of the primary cancer, which were distinct from the factors for the entire group of BM patients. Furthermore, we found that the BMA patients with multiple sites of BM had similar prognosis to the BM&VM patients. These findings together provide us with a further understanding of BM from CRC and reveal that BMA may be a distinct subset of BM from CRC that has unique independent prognostic factors and a good prognosis.