Bmi-1 overexpression tied to distant metastasis, poor survival in NSCLC
Overexpression of B-cell-specific Moloney leukaemia virus insertion site 1 (Bmi-1) is associated with poor overall survival (OS), distant metastasis and tumour size in nonsmall cell lung cancer (NSCLC), according to a new meta-analysis.
Pooled data from 14 studies (n=1,323) showed that Bmi-1 overexpression was significantly associated with tumour size (n=7; odds ratio [OR], 1.79; 95 percent CI, 1.19 to 2.71; p=0.005), poor differentiation (n=7; OR, 1.61; 1.11 to 2.33; p=0.011) and distant metastasis (n=4; OR, 4.69; 1.52 to 14.41; p=0.007).
Similarly, pooled data from eight studies (n=913) showed that Bmi-1 overexpression was significantly associated with poor survival in NSCLC patients (hazard ratio [HR], 1.62; 1.14 to 2.3; p<0.001).
In contrast, Bmi-1 expression showed no significant associations with age (OR, 1.13; 0.86 to 1.49; p=0.372), tumour/node/metastasis staging (OR, 0.91; 0.68 to 1.22; p=0.513), lymph node metastasis (OR, 1.25; 0.71 to 2.22; p=0.434), histology (OR, 1.07; 0.73 to 1.57; p=0.722) and smoking (OR, 1.2; 0.78 to 1.86; p=0.402).
The meta-analysis involved studies that investigated the relationship of Bmi-1 expression and clinical factors and overall survival in histologically confirmed NSCLC patients. Studies that reported HRs and ORs were included, while those that were case studies or animal studies were excluded. The databases of PubMed, Web of Science and Embase were accessed.
Begg test and Egger test were both employed to evaluate the risk of bias of the selected studies. None of the studies showed publication bias.