Table 4.

Sensitivity analyses to assess the robustness of the association between number of dissected lymph nodes and Recurrence-free survival

Number of lymph nodes examined	No. patients	No. events	Adjusted model *
			Hazard ratio (95% confidence interval)	P value
Fewer than 9 a	51	20	1.00 (reference)
At least 9 a	407	98	0.43 (0.26, 0.73)	0.002
Fewer than 9 b	51	20	1.00 (reference)
At least 9 b	407	98	0.45 (0.27, 0.77)	0.003

^a Recounted the number of lymph nodes of single station which higher than 5 to 5

^b Death without recurrence was considered competing events for recurrence-free survival

* Adjusted for age, sex, age-adjusted Charlson Comorbidity Index, surgical year, tumor site, family history of malignancy, histopathological subtype, spread through air space, pT, pN and postoperative adjuvant therapy