The homogeneity and heterogeneity of occurrence, characteristics, and prognosis in hepatocellular carcinoma patients with synchronous and metachronous bone metastasis

Purpose: Based on the one of the largest hepatocellular carcinoma (HCC) population with bone metastasis (BM) from the single center in Tianjin, China, the present study aimed to investigate the risk and survival of synchronous bone metastasis (sBM) and metachronous bone metastasis (mBM) in HCC, and to reveal characteristics and related factors of HCC patients with bone metastasis. Methods: HCC patients with bone metastasis between 2009 and 2017 from Tianjin Medical University Cancer Institute & Hospital, Tianjin, China, were involved. Chi-square test/ Fisher's exact test and Logistic regression were used to estimate the risk factors of bone metastasis in HCC. Kaplan-Meier method was used to estimate the survival of HCC patients, and the Log-rank test was used to analyze the survival of HCC patients. The prognostic factors of HCC patients with BM were identified via Kaplan-Meier method and multivariable COX regression model. Results: Among 4421 HCC patients, 128 patients with BM were identified. Of the 128 patients with BM, 77 patients (60.16%) were with sBM and 51 patients (39.84%) were with mBM. The incidence of sBM in HCC was 1.74% at initial diagnosis. The most common metastatic site of sBM was rib, followed by lumbar, thoracic, and sacral. The median latency time from HCC diagnosis to mBM was six months. The most common site of mBM was thoracic, followed by lumbar, sacral and rib. Alcohol-drinking history (P=0.027), numbers (P=0.023) and size (P=0.008) of intrahepatic tumor, lymph node metastasis (P<0.001), serum ALP (P=0.004) and HGB (P=0.004) level were found to be correlated with the occurrence of BM. The overall survival between non-BM and BM were statistically different (P=0.028). Conclusion: The incidence of sBM in HCC was 1.74% at initial diagnosis. The median latency time from HCC diagnosis to mBM was 6 months. The characteristics between occurrence and prognosis showed significant difference between sBM and mBM. Early identification of high-risk BM population was essential for the improvement of both quality of life and prognosis. The revealed related factors can potentially guide sBM and mBM identification and early diagnosis in HCC.