Association between Bmi1 and clinicopathological status of esophageal squamous cell carcinoma

Table 1 Associations of Bmi-1 mRNA expression in ESCC tissues with clinicopathological characteristics (mean ± SD)

Parameter	Bmi-1 mRNA	P
Age (yr)
≥ 60	2.312 ± 2.171	0.3816
< 60	2.167 ± 2.045
Gender
Male	2.402 ± 2.359	0.2133
Female	1.770 ± 1.690
Lymph node metastases
Yes	3.580 ± 2.487	0.0003
No	1.703 ± 0.758
Stage
III/IV	3.827 ± 2.673	0.0001
I/II	1.590 ± 0.735
Histological grade
I	0.881 ± 0.418	0.000
II	1.858 ± 0.979
III	3.580 ± 2.487

Quantitative real-time PCR was employed to identify Bmi1 mRNA expression. The comparative expression levels were determined as a ratio between Bmi1 and housekeeping gene (β-actin) to correct variation in the amount of mRNA.