Table 2.

Baseline characteristics

Characteristics	p16 positive		p16 negative		Total patients		p-value
	No	%	No	%	No	%
Sex
Males	23	100	144	93.5	167	94.4	0.364
Females	0	0	10	6.5	10	5.6
Age
≤ 55 years	14	60.6	69	44.8	83	46.9	0.150
> 55 years	9	39.1	85	55.2	94	53.1
Smoking
Yes	20	87	142	92.2	162	91.5	0.399
No	3	13	12	7.8	15	8.5
Smokeless tobacco (N = 168)
Yes	16	76.2	97	66	113	67.3	0.051
No	5	23.8	50	34	55	32.7
Subsite
Tonsil	3	13	31	20.3	34	19.3	0.376
Base of tongue	11	47.3	73	47.7	84	47.7
Vallecula	5	21.7	27	17.6	32	18.2
Soft palate	4	17.4	12	7.8	16	9.1
PPW	0	0	10	6.5	10	5.7
Tumourstage
T1-2	7	30.4	44	28.6	51	28.8	0.443
T3	10	43.5	50	32.5	60	33.9
T4	6	26.1	60	39	66	37.3
Nodal stage
N0	8	34.8	39	25.3	47	26.6	0.338
N +	15	65.2	115	74.7	130	73.4
Composite stage
I-II	4	17.4	14	9.1	18	10.2	0.469
III	6	26.1	43	27.9	49	27.7
IV	13	56.5	97	63	110	62.1
EBRT type
Conventional fractionation	19	82.6	120	120	139	79.4	0.686
Altered fractionation	4	17.4	32	32	36	20.6

PPW, Posterior pharyngeal wall; EBRT, External Beam Radiotherapy