Table 4. Risk Factors for Contralateral Nodal Disease in Those With Clinically Negative Contralateral Neck Findings.

Risk Factor	Patient Populationa		Univariate Analysis, OR (95% CI)
	Contralateral pN0 Neck Findings (n = 55)b	Contralateral pN1+ Neck Findings (n = 15)c
Primary tumor location
Lateralized	34 (61.8)	4 (26.7)	6.23 (1.71-22.77)
Crosses midline	15 (27.3)	11 (73.3)
Unknown	6 (10.9)	0
Distance from midline, mean (SD), cm	0.46 (0.40)	0.31 (0.27)	0.32 (0.004-25.05)
Clinical T stage
T0	14 (25.5)	2 (13.3)	NA
T1-T2	34 (61.8)	10 (66.7)	2.06 (0.40-10.62)
T3-T4	7 (12.7)	3 (20.0)	3.00 (0.40-22.30)
Pathologic T stage
T1-T2	45 (81.8)	12 (80.0)	0.87 (0.27-4.74)
T3-T4	10 (18.2)	3 (20.0)
LVI
No	36 (65.5)	8 (53.3)	1.75 (0.55-5.59)
Yes	18 (32.7)	7 (46.7)
Unknown	1 (1.8)	0
PNI
No	50 (90.9)	14 (93.3)	0.89 (0.09-8.64)
Yes	4 (7.3)	1 (6.7)
Unknown	1 (1.8)	0
N stage in ipsilateral neck
N0	4 (7.3)	1 (6.7)	1.10 (0.11-10.63)
N1+	51 (92.7)	14 (93.3)
No. of positive nodes, mean (SD)	2 (2)	3 (4)	1.12 (0.90-1.39)
Largest node, mean (SD), cm	3.53 (1.52)	3.87 (1.29)	1.18 (0.78-1.78)
ECS
Absent	22 (40.0)	5 (33.3)	1.37 (0.40-4.65)
Present	29 (52.7)	9 (60.0)
Unknown	4 (7.3)	1 (6.7)

Abbreviations: BOT, base of tongue; ECS, extracapsular lymph node spread; LVI, lymphovascular invasion; NA, not available; OR, odds ratio; PNI, perineural invasion.

^aUnless otherwise indicated, data are expressed as number (percentage) of patients.

^bRefers to patients who on analysis of pathologic findings had no evidence of disease in contralateral neck nodes.

^cRefers to patients who on analysis of pathologic findings had at least 1 node with evidence of disease in the contralateral neck.