Long-term efficacy and short-term outcomes of intersphincteric resection vs abdominoperineal resection in patients with ultra-low rectal cancer

Table 1 Baseline characteristics of patients before and after propensity score matching, n (%)

Variables	Before PSM			After PSM
	ISR group (n = 435)	APR group (n = 368)	P value	ISR group (n = 289)	APR group (n = 289)	P value
Sex			0.575			0.559
Female	245 (56.3)	200 (54.3)		160 (55.4)	153 (52.9)
Male	190 (43.7)	168 (45.7)		136 (47.1)	136 (47.1)
Age (years)			0.084			0.676
≤ 50	106 (24.4)	71 (19.3)		55 (19.0)	59 (20.4)
> 50	329 (75.6)	297 (80.7)		234 (81.0)	230 (79.6)
BMI (kg/m2)			0.435			0.400
≤ 25	350 (80.5)	304 (82.6)		237 (82.0)	229 (79.2)
> 25	85 (19.5)	64 (17.4)		52 (18.0)	60 (20.8)
ASA grade			0.025			0.970
I	41 (9.4)	27 (7.3)		22 (7.6)	22 (7.6)
II	350 (80.5)	281 (76.4)		228 (78.9)	230 (79.6)
III	44 (10.1)	60 (16.3)		39 (13.5)	37 (12.8)
Tumour diameter (cm)			< 0.001			0.491
≤ 3	225 (51.7)	119 (32.2)		103 (35.6)	111 (38.4)
> 3	210 (48.3)	249 (67.7)		186 (64.4)	178 (61.6)
CEA (ng/mL)			< 0.001			0.846
≤ 5	353 (81.1)	261 (70.9)		218 (75.4)	220 (76.1)
> 5	82 (18.9)	107 (29.1)		71 (24.6)	69 (23.9)
CA19-9 (U/mL)			< 0.001			0.883
≤ 37	410 (94.3)	316 (85.9)		264 (91.3)	263 (91.0)
> 37	25 (5.7)	52 (14.1)		25 (8.7)	26 (9.0)
pT stage			< 0.001			0.819
≤ T3	388 (89.2)	271 (73.6)		243 (84.1)	245 (84.8)
T4	47 (10.8)	97 (26.4)		46 (15.2)	44 (15.2)
pN stage			0.045			0.724
N0	300 (69.0)	229 (62.2)		191 (66.1)	195 (67.5)
N+	135 (31.0)	139 (37.8)		98 (33.9)	94 (32.5)
pTNM stage			< 0.001			0.705
0	36 (14.0)	36 (9.8)		31 (10.7)	31 (10.7)
I	135 (31.0)	77 (20.9)		86 (29.8)	77 (26.6)
II	104 (23.9)	116 (31.5)		74 (25.6)	85 (29.4)
III	135 (31.0)	139 (37.8)		98 (33.9)	94 (32.5)
Histopathology			0.719			0.761
Adenocarcinoma	426 (97.9)	359 (97.6)		283 (97.9)	284 (98.3)
Mucinous adenocarcinoma	9 (2.1)	9 (2.4)		6 (2.1)	5 (1.7)
nCRT			0.383			0.244
No	197 (45.3)	178 (48.4)		151 (52.2)	137 (47.4)
Yes	238 (54.7)	190 (51.6)		138 (47.8)	152 (52.6)
Surgical procedures			0.714			0.864
Laparoscopy	391 (89.9)	337 (91.6)		263 (91.7)	265 (91.7)
Open	34 (7.8)	24 (6.5)		18 (6.2)	18 (6.2)
Robotic	10 (2.3)	7 (1.9)		8 (2.8)	6 (2.1)
ISR approach			-1			-1
Complete trans-pelvic	372 (85.5)	0 (0.0)		249 (86.2)	0 (0.0)
Mixed	63 (14.5)	0 (0.0)		40 (13.8)	0 (0.0)
APR	0 (0.0)	368 (100.0)		0 (0.0)	289 (100.0)

¹Non-participation in propensity score matching.

PSM: Propensity score matching; ISR: Intersphincteric resection; APR: Abdomen perineal resection; BMI: Body mass index; ASA: American Society of Anesthesiologists; nCRT: Neoadjuvant chemoradiotherapy.