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

Because bone metastasis from colorectal cancer is rare, there are little available data regarding such cases.The study aim was to identify the prognostic factors and characteristics associated with survival in colorectal cancer patients with bone metastasis.This was a retrospective study from a prospectively collected database.The study took place in a multidisciplinary, high-volume tertiary cancer center in Japan.Examined were records from 104 consecutive patients treated between 2004 and 2015 for bone metastasis from colorectal cancer.The primary outcome measure was overall survival.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.This study was limited by its retrospective, nonrandomized design, as well as selection bias and performance at a single institute.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.