Ratio of metastatic lymph nodes is more important for rectal cancer patients treated with preoperative chemoradiotherapy

Table 1 Patient and tumor characteristics n (%)

	Non-PCRT,n = 724	PCRT,n = 243	P value
Age (mean ± SD) (yr)	54 ± 10.3	59.2 ± 11.3	< 0.001
< 50	154 (21.3)	80 (32.9)
50-65	346 (47.8)	130 (53.5)	< 0.001
> 65	224 (30.9)	33 (13.6)
Gender			0.005
Male	434 (59.9)	148 (60.9)
Female	290 (40.1)	95 (39.1)
Location1			< 0.001
6-10 cm	474 (65.5)	100 (41.2)
≤ 5 cm	250 (34.5)	143 (58.8)
Sphincter preservation	600 (82.9)	177 (72.8)	< 0.001
Among patients with low rectum	133 (53.2)	81 (56.6)	0.370
LNR2	0.25 ± 0.24	0.252 ± 0.19	0.170
Number of harvested LNs	18.2 ± 8.5	14.8 ± 7.1	< 0.001
< 12 LNs harvested	153 (21.1)	96 (39.5)	< 0.001
Number of positive LNs	3.9 ± 3.7	2.8 ± 2.8	< 0.001
p/yp N category			< 0.001
p/yp N1	445 (61.5)	181 (74.5)
p/yp N2	279 (38.5)	62 (25.5)
Follow-up duration, (Interquartile range) (mo)	60 (39-80)	56 (43-68)	0.540

¹From the anal verge;

²Lymph node ratio. PCRT: Preoperative chemoradiotherapy; LNR: Lymph node ratio; LNs: Lymph nodes.

Table 2 Five-year recurrence-free survival for T-stage subgroups stratified by lymph node ratio and pN category

	No PCRT			P value2	PCRT			P value2
	pN1	pN2	Overall		pN1	pN2	Overall
LNR1	78.6%	60.1%	76.2%	< 0.001	58.7%	42.0%	59.2%	< 0.001
LNR2	59.5%	51.2%	52.9%		27.6%	38.1%	33.8%
Overall	76.3%	53.4%			54.3%	44.3%
P value1	< 0.001				< 0.262

¹RFS according to the LNR;

²RFS according to pN category. PCRT: Preoperative chemoradiotherapy; LNR: Lymph node ratio; RFS: Recurrence-free survival.

Table 3 Five-year recurrence-free survival stratified by lymph node ratio and pN-category according to the number of harvested lymph nodes

	No PCRT				PCRT
	< 12	P value	≥12	P value	< 12	P value	≥12	P value
p/yp N1	67.8%	0.01	79.2%	< 0.001	43.8%	0.90	62.4%	0.080
p/yp N2	43.3%		55.0%		36.5%		47.2%
LNR1	74.2%	0.01	76.6%	< 0.001	50.2%	0.05	63.0%	0.007
LNR2	51.3%		53.6%		31.9%		38.1%

PCRT: Preoperative chemoradiotherapy; LNR: Lymph node ratio.

Table 4 Factors associated with recurrence-free survival: Multivariate analysis

Factor	No PCRT			PCRT
	HR	95%CI	P value	HR	95%CI	P value
p/yp N category			< 0.001			0.380
N1	1.00			1.00
N2	1.90	1.43-2.53		1.21	0.79-1.85
LNR category			< 0.001			0.001
LNR1	1.00			1.00
LNR2	1.97	1.48-2.63		1.94	1.31-2.88
Lymphovascular invasion			0.34
None	1.00			1.00		0.110
Present	1.24	0.93-1.67		1.42	0.89-2.27
Perineural invasion			0.04			0.030
None	1.00			1.00
Undetermined	1.65	1.12-2.43		1.86	1.18-2.93
Location			0.02			0.040
6-10 cm	1.00			1.00
≤ 5 cm	1.34	1.05-1.85		0.62	0.40-0.98
Preoperative CEA			0.02
Normal	1.00
Increased	1.46	1.07-1.98

PCRT: Preoperative chemoradiotherapy; LNR: Lymph node ratio; CEA: Carcinoembryoinc antigen.