Table 2.

Univariate analysis of clinicopathological characteristics and incidence of distant metastasis.

Variables	Incidence of distant metastasis (%)	p value
Sex		0.081
Male	27/573 (5.1)
Female	9/354 (2.5)
Primary site		0.003*
PIOC of the mandible	4/16 (25.0)
Others	32/871 (3.7)
Histological differentiation		< 0.001*
Well/Moderately	26/824 (3.2)
Poorly	10/63 (15.9)
Initial treatment for primary tumor		0.202
Surgery	29/775 (3.7)
Brachytherapy	7/112 (6.3)
pN		< 0.001*
No	5/642 (0.8)
Yes	31/245 (12.7)
Number of metastatic nodes		< 0.001*
0–3	18/821 (2.2)
≥ 4	18/66 (27.3)
Level of metastatic node		< 0.001*
No metastasis or I + II + III	27/869 (3.1)
IV + V	9/18 (50.0)
Contralateral node metastasis		< 0.001*
No	27/850 (3.2)
Yes	10/38 (26.3)
ENE		< 0.001*
No	11/748 (1.5)
Yes	25/139 (18.0)
Postoperative CT and/or RT		< 0.001*
No	7/732 (1.0)
Yes	29/155 (18.7)
Total	36/887 (4.1)

PIOC, primary intraosseous carcinoma; CT, chemotherapy; RT, radiotherapy; ENE, extranodal extension.

*Significant at p < 0.05.