Postoperative circulating tumor DNA detection predicts recurrence and guides adjuvant chemotherapy duration in high-risk stage III colorectal cancer

Table 1 Relationship between postoperative circulating tumor DNA status and clinicopathological features of high-risk stage III colorectal cancer

Clinicopathological features	n	Postoperative ctDNA		χ2	P value
		Negative (n = 29)	Positive (n = 21)
Age
< 60 years	20	9	11	2.313	0.128
≥ 60 years	30	20	10
Sex
Male	27	15	12	0.144	0.704
Female	23	14	9
Tumor location
Rectum	16	11	5	1.116	0.291
Colon	34	18	16
Tumor differentiation
Moderate/well-differentiated	30	17	13	0.055	0.815
Poorly differentiated/mucinous carcinoma	20	12	8
Tumor stage
IIIb	29	20	9	3.408	0.065
IIIc	21	9	12
T stage
T3	26	17	9	1.213	0.271
T4	24	12	12
N stage
N1	17	11	6	0.475	0.490
N2	33	18	15
Perineural invasion
Yes	31	19	12	0.363	0.547
No	19	10	9
Vascular invasion
Yes	25	12	13	2.053	0.152
No	25	17	8
CEA (ng/mL)
< 5	23	12	11	0.539	0.441
≥ 5	27	17	10
Recurrence
Yes	15	5	10	5.352	0.021
No	35	24	11

ctDNA: Circulating tumor DNA; CEA: Carcinoembryonic antigen.

Table 2 Univariable and multivariable Cox proportional hazards regression analysis of risk factors for recurrence-free survival in patients with high-risk stage III colorectal cancer

Parameter	Univariable analysis		Multivariate analysis
	HR (95%CI)	P value	HR (95%CI)	P value
Age (≥ 60 years vs <60 years)	0.613 (0.142-2.459)	0.512	-	-
Sex (male vs female)	0.257 (0.062-1.055)	0.059	-	-
Tumor location (rectum vs colon)	0.238 (0.044-1.273)	0.093	-	-
Tumor differentiation (moderate/well-differentiated vs poorly differentiated/mucinous carcinoma)	0.899 (0.222-3.631)	0.881	-	-
Tumor stage (IIIb vs IIIc)	0.172 (0.035-0.860)	0.032	0.241 (0.079-0.739)	0.013
T stage (T3 vs T4)	0.212 (0.044-1.015)	0.028	0.561 (0.193-1.632)	0.289
N stage (N1 vs N2)	0.212 (0.044-1.015)	0.052	-	-
Perineural invasion (no vs yes)	2.580 (0.529-12.573)	0.241	-	-
Vascular invasion (no vs yes)	1.277 (0.263-6.207)	0.761	-	-
Number of harvested lymph nodes (≥ 12 vs < 12)	1.678 (0.366-7.681)	0.505	-	-
Adjuvant chemotherapy duration (3 months vs 6 months)	2.852 (0.527-15.434)	0.224	-	-
CEA (ng/mL) (< 5 vs ≥ 5)	0.526 (0.116-2.381)	0.405	-	-
Postoperative ctDNA status (positive vs negative)	6.001 (1.203-29.927)	0.029	4.304 (1.412-13.115)	0.010

ctDNA: Circulating tumor DNA; HR: Hazard ratio; CI: Confidence interval; CEA: Carcinoembryonic antigen.