Table 1.

Clinical characteristics of enrolled patients from the multicenter cohorts

	Discovery cohort		Training cohort	Internal validation cohort	External validation cohort
	Guangzhou cohort	Beijing discovery cohort	Beijing training cohort	Beijing validation cohort	Integrated external validation cohort
	(N = 28)	(N = 30)	(N = 71)	(N = 71)	(N = 52)
Age
≥60	8	17	32	38	40
<60	20	13	39	33	12
Sex
Male	25	28	64	63	37
Female	3	2	7	8	15
Tumor location
Upper	4	3	19	18	14
Middle	18	19	40	38	31
Lower	6	8	12	15	7
Tumor differentiation
Well	7	3	6	4	15
Moderate	16	20	37	36	22
Poor	5	7	28	31	15
Clinical T stage
T2	8	2	3	6	13
T3	20	11	45	41	32
T4	0	16	23	24	7
Clinical N stage
N0	0	3	9	14	25
N1, N2, N3	28	27	62	57	27
Clinical M stage
M0	28	30	71	71	52
M1	0	0	0	0	0
Clinical TNM stage
II	8	5	8	16	26
III	20	25	63	55	26
nCRT response
pCR	11	11	23	24	17
<pCR	17	19	48	47	35

nCRT neoadjuvant chemoradiotherapy, pCR pathological complete response, <pCR less than pCR