Table 2. Unadjusted and adjusted hazard ratios of positive ALK IHC status for tumor recurrence in patients with stage IA lung adenocarcinoma who underwent surgical resection.

Variables	ALK IHC status*		P value
	Negative (n=286)	Positive (n=23)
Unadjusted	Ref	2.55 (1.05, 6.19)	0.038
Adjusted†	Ref	2.64 (1.08, 6.44)	0.033

Values represent the hazard ratio (95% confidence interval). *, ALK-positive was defined as an IHC score ≥2; ^†, initial clinical variables entered into the Cox’s proportional hazard model were age, sex, body mass index, smoking history, T stage (T1a or T1b), and surgery type. Using a stepwise backward selection method, with elimination of variables exhibiting P value >0.1 in univariate analyses, sex, T stage, and surgery type were included in the final model. ALK, anaplastic lymphoma kinase; IHC, immunohistochemistry.