Clinicopathologic characteristics
Clinicopathologic characteristics of all HCC patients are listed in Table 1.
Expression of serum lnc34a levels in patients with HCC
In order to investigate the hypothesis that the serum level of lnc34a is a potential biomarker for the bone metastases of HCC, qRT-PCR for the lnc34a expression detection was performed with serum samples from 18 HCC patients with bone metastases and 139 cases without bone metastases. As shown in Fig 1, the serum expression levels of lnc34a in patients with bone metastases were significantly higher than that in those without bone involvement. The 157 HCC patients were classified into high serum lnc34a group (n=80) and low serum lnc34a group (n=77) according to the median serum lnc34a expression level. Of the 18 patients with bone metastasis, 15 (83.3%) had high lnc34a expression.
Association between serum lnc34a expression levels and clinicopathological factors in patients with HCC
We next analyzed the relationship between the expression of serum lnc34a and clinicopathological characteristics of the 157 HCC patients. As shown in Table 2, the analysis revealed that serum lnc34a levels were significantly related to certain clinicopathological parameters, including vascular invasion (p = 0.032) and BCLC stage (p = 0.014). Almost 82.3% patients in our study were infected with hepatitis B. However, the lnc34a expression was uncorrelated with HBsAg(p = 0.173), which may due to the limited number of patients in this study.
At the final follow-up, 50 (31.8%) patients were found to have extrahepatic metastases. And among these patients, 23 patients developed lung metastasis, 20 patients developed lymph node metastasis, and 18 patients developed bone metastases. To eliminate the possibility of other extrahepatic metastases affecting the expression of lnc34a, we further carried out a subgroup analysis of its expression with other extrahepatic metastases. Correlation analysis revealed that the serum lnc34a expression level was positive correlated with bone metastasis in HCC (r = 0.233, p = 0.003), while there was no significant correlations between circulating lnc34a expression and lung (r = 0.046, p = 0.566) or lymph node metastasis (r = 0.031, p = 0.701).
Cox regression analysis of potential biomarkers and bone metastasis
As shown in Table 3, univariate analyses indicated that vascular invasion (p < 0.001), and BCLC stage (p = 0.001) and lnc34a expression (p = 0.008) were significantly associated with HCC bone metastasis. However, there was no significant correlation between bone metastasis and clinicopathological factors such as age, gender, HBsAg, HCV-Ab, AFP, ALT, γ-GT, liver cirrhosis, Child-Pugh score, tumor differentiation, tumor size, tumor number and tumor encapsulation. And multivariate analyses further revealed that vascular invasion (95% confidence interval [CI], 2.291-19.157; p < 0.001), BCLC stage (95% CI, 1.244-12.287; p = 0.020), and lnc34a expression (95% CI, 1.107-13.629; p = 0.034) were associated with bone metastasis (Table 4). Therefore, high serum lnc34a expression, vascular invasion and BCLC stage were independent risk factors for bone metastasis prediction in HCC patients.