Table 1.

Univariate analysis results show factors associated with pathological lateral lymph node metastasis

Factors	LLN-positive (n = 18)	LLN-negative (n = 49)	Univariate analysis (P value)
Patient factors
Age (years)	66.5 (47-83)	65 (33-78)	0.2529
Gender (male/female)	9/9	29/20	0.5024
Preoperative therapy (none/chemotherapy/chemoradiotherapy)	13/2/3	39/6/4	0.6262
cT (2/3/4a/4b)	0/8/2/8	3/34/4/8	0.0641
Clinically suspected mesorectal LN metastasis (+/−)	16/2	25/24	0.0027
MRI factors
MRI-AV (mm)	34.5 (9-66)	36 (0.5-95)	0.4613
Enlarged LLN (positive/negative) a	16/2	9/40	< 0.0001
MRI-EMVI (positive/negative)	14/4	18/31	0.0024
MRF involvement (positive/negative)	9/7	17/29	0.1800
Surgical factors
Approach to LLN dissection (laparoscopy/open)	5/13	32/17	0.0058
Operation (LAR/sLAR/ISR/APR/TPE)	1/4/1/10/2	7/27/1/13/1	0.0500
Pathological factors
Tumor size (mm)	35 (30–70)	50 (30–80)	0.6715
pT (≤ 2/≤ 3)	18/0	41/8	0.0289
Mesorectal LN metastasis (positive/negative)	12/6	22/27	0.1114
v (positive/negative)	16/2	37/12	0.2097
ly (positive/negative)	5/13	6/43	0.1443
Perineural invasion (positive/negative)	8/10	24/23	0.6326
Differentiation (Well or moderate/poor)	15/3	47/2	0.1044
CRM (0/1)	18/0	49/0	–
Postoperative course
Recurrence (positive/negative)	5/13	13/36	0.9189
Site of overall recurrence (local recurrence/distant recurrence/local and distant recurrence)	0/4/1	2/10/1	0.4177
LLN recurrence (yes/no)	1/4	1/12	0.4782

Values are the median (range) or number, as indicated

LN lymph node, MRI magnetic resonance imaging, AV anal verge, LLN lateral lymph node, EMVI extramural venous invasion, MRF mesorectal fascia, LAR low anterior rectectomy, sLAR super low anterior rectectomy, ISR intersphincteric resection, APR abdominoperineal resection, TPE total pelvic exenteration, v venous invasion, ly lymphatic invasion, CRM circumferential resection margin

^aPositive/negative value of the short axis of lateral lymph node (mm) (≥ 5/< 5)