Clinical features and KRAS mutation in colorectal cancer with bone metastasis

Bone metastasis is known as a poor prognostic factor in colorectal cancer (CRC), but its clinical manifestations and outcomes are uncertain. CRC with bone metastasis was searched from January 2006 to April 2016. Of 11,551 CRC patients, 321 (2.7%) patients had bone metastasis. Bone-only metastasis was found in only 8.7% of patients. Synchronous bone metastasis was present in 147 (45.8%) patients. In patients with metachronous bone metastasis, the median time from CRC diagnosis to bone metastasis (TTB) was 27.2 months. KRAS mutation status was a marginally significant factor affecting TTB (median TTB, KRAS wild-type or mutation: 29 or 25.8 months, respectively, P = 0.068). Skeletal-related events (SREs) were noted in 200 (62.3%) patients. Median overall survival (OS) from diagnosis of bone metastasis was 8.0 months. On multivariate analysis, multi-organ metastasis, peritoneal metastasis, neutrophil-to-lymphocyte ratio (NLR) ≥ 2.7, and alkaline phosphatase (ALP) ≥ 123 were independent factors for OS. Palliative chemotherapy prolonged survival in CRC patients with bone metastasis (HR 0.25, 95% CI 0.2–0.33). In conclusion, bone metastasis of CRC is rare, but it is related to SREs. Most patients have other organ metastasis and survival is 8.0 months. Attention should be paid to bone metastasis in CRC patients.