Optimal postoperative surveillance strategies for stage III colorectal cancer

Table 1 Demographic and clinical characteristics of participants according to surveillance intensity (n = 1888)

Variables	Surveillance intensity		P value
	Lower intensity (n = 1024)	Higher intensity (n = 864)
Age, mean (IQR)	60.0 (52.0–68.0)	58.0 (50.3–67.0)	0.178
Gender, n (%)			0.502
Male	607 (59.3)	528 (61.1)
Female	417 (40.7)	336 (38.9)
Cancer site, n (%)			0.795
Colon	365 (35.6)	303 (35.1)
Rectum	659 (64.4)	561 (64.9)
Differentiation, n (%)			0.027
WD/MD	945 (92.3)	781 (90.4)
PD/SRC/MUC	72 (7.0)	82 (9.5)
Unknown	7 (0.7)	1 (0.1)
Total lymph nodes, n (%)			0.001
< 12	129 (12.6)	49 (5.7)
≥ 12	895 (87.4)	815 (94.3)
(y) pT, n (%)			0.002
0	12 (1.2)	6 (0.7)
1	66 (6.4)	36 (4.2)
2	126 (12.3)	89 (10.3)
3	770 (75.2)	660 (76.4)
4	50 (4.9)	73 (8.4)
(y) pN, n (%)			0.010
1c	14 (1.4)	8 (0.9)
1	735 (71.8)	570 (66.0)
2	275 (26.8)	286 (33.1)
Perineural invasion, n (%)	219 (21.4)	262 (30.3)	< 0.001
Lymphovascular invasion, n (%)	371 (36.2)	344 (39.8)	0.110
Resection margin, n (%)			0.004
Positive	18 (1.7)	41 (4.7)
Unknown	7 (0.7)	8 (0.9)
APCT, mean ± SD	1.49 ± 0.47	2.67 ± 1.31	< 0.001
CCT, mean ± SD	0.62 ± 0.41	1.48 ± 0.91	< 0.001
Total imaging studies, mean ± SD	2.11 ± 0.58	4.14 ± 1.64	< 0.001

IQR: Inter-quartile range; WD: Well differentiated; MD: Moderately differentiated; PD: Poorly differentiated; SRC: Signet ring cell type; MUC: Mucinous carcinoma; APCT: Abdomino-pelvic computed tomography; SD: Standard deviation; CCT: Chest computed tomography.

Table 2 Factors affecting overall survival of participants

Factors	Univariate		Multivariate
	OR (95%CI)	P value	OR (95%CI)	P value
Age (yr)	1.027 (1.019–1.035)	< 0.001	1.031 (1.023–1.039)	< 0.001
Sex	0.704 (0.592–0.836)	< 0.001	0.711 (0.598–0.845)	< 0.001
Surveillance intensity	1.650 (1.400–1.945)	< 0.001	1.531 (1.295–1.808)	< 0.001
Differentiation
WD/MD	Ref.		Ref.
PD/SRC/MUC	1.832 (1.424–2.356)	< 0.001	1.660 (1.285–2.143)	< 0.001
(y) pT stage
0–2	Ref.		Ref.
3–4	1.937 (1.491–2.516)	< 0.001	1.461 (1.111–1.921)	0.007
(y) pN stage
1c	Ref.		Ref.
1	5.136 (0.721–36.571)	0.102	4.754 (0.667–33.906)	0.12
2	9.322 (1.308–66.457)	0.026	7.067 (0.988–50.556)	0.051
Lymphovascular invasion	1.607 (1.365–1.891)	< 0.001	1.256 (1.057–1.491)	0.01
Perineural invasion	1.818 (1.535–2.154)	< 0.001	1.466 (1.224–1.755)	< 0.001
Resection margin1	1.972 (1.360–2.860)	< 0.001	1.603 (1.097–2.341)	0.015

¹Resection margin indicated circumferential resection margin, and were calculated with rectal cancer patients. OR: Odds ratio; CI: Confidence interval; Ref: Reference; WD: Well differentiated; MD: Moderately differentiated; PD: Poorly differentiated; SRC: Signet ring cell type; MUC: Mucinous carcinoma.

Table 3 Factors affecting recurrence-free interval of participants

Factors	Univariate		Multivariate
	OR (95%CI)	P value	OR (95%CI)	P value
Age (yr)	0.995 (0.987–1.002)	0.165	0.999 (0.991–1.006)	0.715
Sex	0.907 (0.765–1.076)	0.262
Surveillance intensity	2.218 (1.870–2.632)	< 0.001	1.999 (1.680–2.377)	< 0.001
Differentiation
WD/MD	Ref.		Ref.
PD/SRC/MUC	1.507 (1.151–1.974)	0.003	1.287 (0.979–1.694)	0.071
(y) pT stage
0–2	Ref.		Ref.
3–4	2.118 (1.610–2.785)	< 0.001	1.596 (1.197–2.127)	0.001
(y) pN stage
1c	Ref.		Ref.
1	2.737 (0.682–10.989)	0.156	2.501 (0.621–10.063)	0.197
2	5.260 (1.308–21.156)	0.019	3.813 (0.943–15.413)	0.060
Lymphovascular invasion	1.460 (1.236–1.724)	< 0.001	1.143 (0.957–1.364)	0.140
Perineural invasion	1.949 (1.641–2.313)	< 0.001	1.431 (1.192–1.719)	< 0.001
Resection margin1	2.192 (1.529–3.144)	< 0.001	1.565 (1.083–2.262)	0.017

¹Resection margin indicated circumferential resection margin, and were calculated with rectal cancer patients. OR: Odds ratio; CI: Confidence interval; Ref: Reference; WD: Well differentiated; MD: Moderately differentiated; PD: Poorly differentiated; SRC: Signet ring cell type; MUC: Mucinous carcinoma.

Table 4 Factors affecting post-recurrence survival of participants

Factors	Univariate		Multivariate
	OR (95%CI)	P value	OR (95%CI)	P value
Age (yr)	1.015 (1.007–1.024)	< 0.001	1.015 (1.006–1.024)	0.001
Sex	0.824 (0.676–1.004)	0.054	0.842 (0.688–1.032)	0.098
Image intensity	0.971 (0.799–1.179)	0.767
Differentiation
WD/MD	Ref.		Ref.
PD/SRC/MUC	2.632 (1.779–3.137)	< 0.001	2.072 (1.553–2.766)	< 0.001
(y) pT stage
0–2	Ref.
3–4	1.146 (0.833–1.576)	0.401
(y) pN stage
1c	Ref.
1	2.139 (0.300–15.256)	0.448
2	3.363 (0.471–24.009)	0.226
Lymphovascular invasion	1.456 (1.204–1.760)	< 0.001	1.152 (0.940–1.412)	0.174
Perineural invasion	1.384 (1.141–1.677)	0.001	1.284 (1.045–1.579)	0.018
Resection margin1	1.416 (0.966–2.075)	0.075	1.266 (0.856–1.871)	0.237
Curative resection	0.296 (0.229–0.381)	< 0.001	0.331 (0.255–0.428)	< 0.001

¹Resection margin indicated circumferential resection margin, and were calculated with rectal cancer patients. OR: Odds ratio; CI: Confidence interval; Ref: Reference; WD: Well differentiated; MD: Moderately differentiated; PD: Poorly differentiated; SRC: Signet ring cell type; MUC: Mucinous carcinoma.