Table 4.

Subgroup analysis through multivariate analysis by Cox hazard model

Subgroup	Adjuvant chemotherapy	No adjuvant chemotherapy	RFS		OS
			HR (95% CI)	p value	HR (95% CI)	p value
Visceral pleural involvement (n = 258)	122	136	0.450 (0.241–0.841)	0.012	0.146 (0.045–0.471)	0.001
Adenocarcinoma (n = 237)	107	130	0.390 (0.196–0.776)	0.007	0.079 (0.011–0.590)	0.013
Tumor size ≤ 3 cm (n = 204)	98	106	0.453 (0.214–0.959)	0.039	0.135 (0.032–0.568)	0.006
Visceral pleural involvement and tumor size ≤ 3 cm (n = 203)	98	105	0.453 (0.214–0.958)	0.038	0.135 (0.032–0.567)	0.006

The multivariate analysis was conducted using a backward elimination procedure for variables with p < 0.2 in the univariate analysis. In univariate analysis, adjuvant chemotherapy, age, sex, histology, tumor diameter, smoking history, and high-risk factors were analyzed.

RFS, recurrence-free survival; OS, overall survival; HR, hazard ratio; CI, confidence interval.