Table 2. Correlation between circulating plasma DNA levels and clinic-pathological parameters of NSCLC patients.

Characteristics	Mean rank of plasma DNA level(ng/ml)
	Cases (n = 104)	P* value
Histological type
Epidermoid	51.91	0.981
Non-Epidermoid	52.05
Tumor stage
I/II	64.25	0.427
III/IV	52.03

^*Mann-Whitney test.