A. Univariant analysis for tumor onset age, smoking and drinking habits, cervical lymph node status, cancer stage, lymphovascular permeation and survival status were different between DM and non-DM groups. Multivariate logistical regression analysis showed age, survival status and lymph node status were associated with DM.

	Non-DM (N = 487)		DM (N = 126)		Total (N = 613)		P-value	OR	95% C.I.	P-value
	N	%	N	%	N	%
Gender							0.449
Male	454	93.2%	115	91.3%	569	92.8%
Female	33	6.8%	11	8.7%	44	7.2%
Tobacco smoking							0.4
Daily	290	59.5%	70	55.6%	360	58.7%
Non-smoker	197	40.5%	56	44.4%	253	41.3%
Alcohol abuse							0.6
Daily	51	10.5%	15	11.9%	66	10.8%
None or social	436	89.5%	111	88.1%	547	89.2%
Age (yr)	52.46 ± 11.30		56.42 ± 9.46		53.28 ± 11.06		p < 0.001	1.04	1.02–1.06
Survival status							p < 0.001
Dead	128	26.3%	70	55.6%	198	32.3%		2.59	1.65–4.05	p < 0.001
Survival	359	73.7%	56	44.4%	415	67.7%		1.00
N status							p < 0.001
N = 0	317	65.4%	55	43.7%	372	60.9%		1.00
N > 0	168	34.6%	71	56.3%	239	39.1%		1.68	1.01–2.79	0.044
Tumor size							0.081
T1 – T3	215	44.3%	45	35.7%	260	42.6%
T4	270	55.7%	81	64.3%	351	57.4%
Tumor stage							p < 0.001
I–II	126	26.0%	14	11.1%	140	22.9%		1.00
III–IV	359	74.0%	112	88.9%	471	77.1%		1.55	0.8–3.03	0.196
Lymphovascular permeation							0.031
Positive	81	16.9%	31	25.4%	112	18.6%		0.89	0.51–1.54	0.669
Negative	398	83.1%	91	74.6%	489	81.4%		1.00
Cell differentation							0.572
Well	178	36.6%	42	33.3%	220	35.9%
Moderate	278	57.1%	73	57.9%	351	57.3%
Poor	31	6.4%	11	8.7%	42	6.9%
Perineural invasion							0.306
Negative	381	78.9%	91	74.6%	472	78.0%
Positive	102	21.1%	31	25.4%	133	22.0%