Table 1. Patient characteristics according to tumour methylation status.

	Tumour hypermethylation
	Informative (n=27)a	Non-informative (n=15)	P-valueb
Age, years
Mean±s.d.	59.67±9.7	57.07±10.46
Median (maximum, minimum)	61 (32, 77)	61 (39, 73)	0.72
Sex, n (%)
Male	22 (81.5)	12 (80)
Female	5 (18.5)	3 (20)	1
Site, n (%)
Oral cavity	10 (37.0)	6 (40.0)
Oropharynx	10 (37.0)	2 (13.3)
Hypopharynx	5 (18.5)	3 (20.0)
Larynx	2 (7.4)	4 (26.7)	0.218
Tumour stage, n (%)
I–II	8 (29.6)	2 (13.3)
III–IV	19 (70.4)	13 (86.7)	0.286
Histopathological gravity signsc, n (%)
No	24 (88.9)	10 (66.7)
Yes	3 (11.1)	5 (33.3)	0.11
Adjuvant therapyd, n (%)
No	14 (51.9)	12 (80.0)
Yes	13 (48.1)	3 (20.0)	0.102
Disease-specific events,n (%)
No	20 (74.1)	6 (40.0)
Yes	7 (25.9)	9 (60.0)	0.047
Disease-specific death,n (%)
No	22 (81.5)	6 (40.0)
Yes	5 (18.5)	9 (60.0)	0.015

^aInformative: high level of gene promotor hypermethylation (WTMI ⩾ 5%).

^bFisher's exact test.

^cHistopathological gravity signs: perineural invasion, angiolymphatic invasion or both.

^dConcurrent chemoradiotherapy or radiotherapy alone.