Characteristics and Prognostic Factors of Bone Metastasis in Patients With Colorectal Cancer.

BACKGROUND: Because bone metastasis from colorectal cancer is rare, there are little available data regarding such cases. OBJECTIVE: The study aim was to identify the prognostic factors and characteristics associated with survival in colorectal cancer patients with bone metastasis. DESIGN: This was a retrospective study from a prospectively collected database. SETTINGS: The study took place in a multidisciplinary, high-volume tertiary cancer center in Japan. PATIENTS: Examined were records from 104 consecutive patients treated between 2004 and 2015 for bone metastasis from colorectal cancer. MAIN OUTCOME MEASURES: The primary outcome measure was overall survival. RESULTS: The spine was the most common site of bone metastasis from colorectal cancer. Right colon cancer correlated significantly with long bone metastasis (p = 0.046), whereas left colon cancer correlated significantly with spinal bone metastasis (p = 0.034). Liver metastasis was also significantly correlated with spinal bone metastasis (p = 0.036). The median interval between the primary therapy for colorectal cancer and the metachronous diagnosis of bone metastasis was 20.0 months (quartile 1 to quartile 3, 9.0-46.5 mo). The median survival time from diagnosis of bone metastasis from colorectal cancer was 5.0 months (95% CI, 4.0-9.0 mo), and the 1-year survival rate was 30.0% (95% CI, 21.1%-39.4%). Multivariate analysis revealed that = 2 extra-bone metastatic organs, hypercalcemia, and pathologic fractures were independent poor prognostic factors (p < 0.001, 0.001, and 0.033). The number of extra-bone metastatic organs correlated with prognosis. LIMITATIONS: This study was limited by its retrospective, nonrandomized design, as well as selection bias and performance at a single institute. CONCLUSIONS: The location of colorectal cancer correlates significantly with the site of bone metastasis; the prognosis of patients with bone metastasis from colorectal cancer is very poor, and the significant prognostic factors are number of extra-bone metastatic organs, hypercalcemia, and pathologic fractures. See Video Abstract at http://links.lww.com/DCR/A589.