Table 1.

Distribution of selected characteristics of the patient cohort (n =1,287)

	Total		SPM-Free		SPM
Variable	No.	%	No.	%	No.	%	P-valuesc
Total patients	1,287	100	1,167	90.7	120	9.3
Age
≤ median (57 years)	664	51.6	625	53.6	39	32.5	< .001
> median (57 years)	623	48.4	542	46.4	81	67.5
Sex
Male	977	75.9	883	75.7	94	78.3	0.515
Female	310	24.1	284	24.3	26	21.7
Ethnicity
Non-Hispanic White	1,089	84.6	995	85.3	94	78.3	0.050
Other	198	15.4	172	14.7	26	21.7
Smoking
Never	345	26.8	320	27.4	25	20.8	0.121
Ever	942	73.2	847	72.6	95	79.2
Alcohol
Never	336	26.1	309	26.5	27	22.5	0.345
Ever	951	73.9	858	73.5	93	77.5
Index Cancer Site
Oral cavity	416	32.3	378	32.3	38	31.7	0.316
Oropharynx	575	44.7	527	45.2	48	40.0
Larynx/Hypopharynx	296	23.0	262	22.5	34	28.3
Index Cancer Stage
I or II	324	25.2	292	25.0	32	26.7	0.693
III or IV	963	74.8	875	75.0	88	73.3
Treatment
Surgery only	229	17.8	208	17.8	21	17.5	0.889
Surgery + Adjuvant Txa	320	24.9	287	24.6	33	27.5
XRTb	329	25.5	301	25.8	28	23.3
XRT + Chemotherapy	409	31.8	371	31.8	38	31.7

^aAdjuvant Treatment: adjuvant radiotherapy and/or chemotherapy

^bXRT: radiotherapy

^cP values were calculated from chi-square test