Table 1.

Patient characteristics.

	Characteristics	No. of patients (N = 138)	Training/validation set (N = 87)	Test set (N = 51)
Gender	Male	106	62	44
	Female	32	25	7
Age (years)	Range	46–94	46–94	46–89
	Mean ± SD	71.43 ± 9.44	71.35 ± 9.37	71.55 ± 10.00
Treatment	Radiotherapy only	68	30	28
	Chemoradiotherapy	70	57	23
Histology	Adenocarcinoma	82	51	29
	Squamous cell carcinoma	56	36	22
Clinical stage	I	0	0	0
	II	43	26	17
	III	95	61	34
	IV	0	0	0