Development and validation of a nomogram for predicting metachronous peritoneal metastasis in colorectal cancer: A retrospective study

Table 1 Baseline characteristics of patients (n = 878), n (%)

Variables	Training cohort (n = 586)	Validation cohort (n = 292)	P value
Gender			0.777
Male	321 (54.8)	157 (53.8)
Female	265 (45.2)	135 (46.2)
Age (yr)			0.924
≥ 60	293 (50.0)	147 (50.3)
< 60	293 (50.0)	145 (49.7)
BMI (kg/m2)			0.683
≥ 25	154 (26.3)	73 (25.0)
< 25	432 (73.7)	219 (75.0)
Preoperative ascites			0.794
Yes	80 (13.7)	38 (13.0)
No	506 (86.3)	254 (87.0)
Operation mode			0.228
Open	183 (31.2)	103 (35.3)
Laparoscopic	403 (68.8)	189 (64.7)
Anastomotic leakage			0.585
Yes	44 (7.5)	25 (8.6)
No	542 (92.5)	267 (91.4)
Tumor site			0.767
Right colon	160 (27.3)	80 (27.4)
Left colon	176 (30.0)	94 (32.2)
Rectum	250 (42.7)	118 (40.4)
Tumor size (cm)			0.223
≥ 5	254 (43.3)	114 (39.0)
< 5	332 (56.7)	178 (61.0)
Tumor type			0.819
Ulcer	395 (67.4)	202 (69.2)
Uplift	152 (25.9)	70 (24.0)
Infiltrating	39 (6.7)	20 (6.8)
Differentiation			0.448
Well/moderate	519 (88.6)	253 (86.6)
Poor/undifferentiated	67 (11.4)	39 (13.4)
Histology			0.707
Adenocarcinoma	497 (84.8)	245 (83.9)
Mucinous	69 (11.8)	39 (13.4)
Signet-ring	20 (3.4)	8 (2.7)
T stage			0.650
1	54 (9.2)	21 (7.2)
2	137 (23.4)	64 (21.9)
3	272 (46.4)	146 (50.0)
4	123 (22.0)	61 (20.9)
N stage			0.976
0	263 (44.9)	129 (44.2)
1	168 (28.7)	84 (28.8)
2	155 (26.4)	79 (27.1)
Examined lymph nodes			0.147
≥ 12	509 (86.9)	243 (83.2)
< 12	77 (13.1)	49 (16.8)
Nerve invasion			0.985
Yes	185 (31.6)	92 (31.5)
No	401 (68.4)	200 (68.5)
Vascular invasion			0.680
Yes	213 (36.3)	102 (34.9)
No	373 (63.7)	190 (65.1)
CEA			0.535
Normal	344 (58.7)	165 (56.5)
Elevated	242 (41.3)	127 (43.5)
CA125			0.778
Normal	349 (59.6)	171 (58.6)
Elevated	237 (40.4)	121 (41.4)
CA199			0.781
Normal	490 (83.6)	242 (82.9)
Elevated	96 (16.4)	50 (17.1)
KRAS mutation			0.971
Wild	370 (63.1)	184 (63.0)
Mutation	216 (36.9)	108 (37.0)
NRAS mutation			0.392
Wild	561 (95.7)	283 (96.9)
Mutation	25 (4.3)	9 (3.1)
BRAF mutation			0.783
Wild	514 (87.7)	258 (88.4)
Mutation	72 (12.3)	34 (11.6)
MSI status			0.612
MSS/MSI-L	509 (86.9)	250 (85.6)
MSI-H	77 (13.1)	42 (14.4)
Peritoneal metastasis			0.600
Yes	521 (88.9)	263 (90.1)
No	65 (11.1)	29 (9.9)

BMI: Body mass index; CEA: Carcinoembryonic antigen; BRAF: V-raf murine sarcoma viral oncogene homolog B; CA125: Carbohydrate antigen 125; CA19-9: Carbohydrate antigen 19-9; KRAS: Kirsten rat sarcoma viral oncogene homolog; NRAS: Neuroblastoma RAS viral oncogene homolog; BRAF: V-raf murine sarcoma viral oncogene homolog B; MSI: Microsatellite instability; MSI-L: MSI-Low; MSI-H: MSI-High.

Table 2 Risk factors for metachronous peritoneal metastasis in colorectal cancer

Risk factors	Multivariate logistic regression
	OR	95%CI	P value
Tumor site
Right colon	1
Left colon	0.461	0.231-0.917	0.027
Rectum	0.250	0.120-0.520	< 0.001
Histology
Adenocarcinoma	1
Mucinous	2.993	1.441-6.220	0.003
Signet-ring	6.453	2.122-19.625	0.001
T stage
T1	1
T2	1.822	0.364-9.103	0.465
T3	2.284	0.498-10.484	0.288
T4	6.871	1.487-31.736	0.014
CA125
Normal	1
Elevated	2.176	1.211-3.912	0.009
BRAF mutation
Wild	1
Mutation	2.586	1.277-5.236	0.008
MSI status
MSS/MSI-L	1
MSI-H	2.547	1.245-5.212	0.010

CRC: Colorectal cancer; OR: Odds ratio; CI: Confidence interval; MSI: Microsatellite instability; MSS: Microsatellite stability; MSI-L: MSI-Low; MSI-H: MSI-High.

Table 3 Subgroup analysis of the risk of metachronous peritoneal metastasis, n (%)

	m-PM		P value
	No	Yes
Low-risk group	672 (94.4)	40 (5.6)	< 0.001
High-risk group	112 (67.5)	54 (32.5)

m-PM: Metachronous peritoneal metastasis.