Table 6. Partial correlation analysis for evaluation the interaction of covariates on the correlation between the OS of patients with positive nodal metastasis and the special variable associated with nodal metastasis.

Control variables	Correlationship	Correlation value	P value
NLNs	Between the PLNs and the postoperative OS of enrolled patients	−0.369	<0.001
PLNs	Between the NLNs and the postoperative OS of enrolled patients	0.247	<0.001
RPDL	Between the PLNs and the postoperative OS of enrolled patients	−0.015	0.801
RPDL	Between the NLNs and the postoperative OS of enrolled patients	−0.015	0.792
RNPL	Between the PLNs and the postoperative OS of enrolled patients	−0.330	<0.001
RNPL	Between the NLNs and the postoperative OS of enrolled patients	0.147	0.011