Table 2. Patient and tumor characteristics according to postoperative ctDNA status.
Characteristics*All patients
(n = 230)
Postoperative
ctDNA-positive
(n = 20)
Postoperative
ctDNA-negative
(n = 210)
Age (years)
  Median
[interquartile
range (IQR)]
65 (59–73)64 (54–68)66 (59–74)
  Range23–8743–8623–87
Sex, no. (%)
  Male131 (57)10 (50)121 (58)
  Female99 (43)10 (50)89 (42)
Tumor site, no. (%)
  Right colon103 (45)5 (25)98 (47)
  Left colon127 (55)15 (75)112 (53)
Differentiation, no. (%)
  Well/moderate193 (84)18 (90)175 (83)
  Poor37 (16)2 (10)35 (17)
T stage, no. (%)
  T3192 (83)17 (85)175 (83)
  T438 (17)3 (15)35 (17)
Lymph node yield, no. (%)
  <1229 (13)5 (25)24 (11)
  ≥12201 (87)15 (75)186 (89)
Lymphovascular invasion, no./total no. (%)
  Yes41/221 (19)6/20 (30)35/201 (17)
  No180/221 (81)14/20 (70)166/201 (83)
MMR status, no. (%)
  Proficient189 (82)19 (95)170 (81)
  Deficient41 (18)1 (5)40 (19)
Clinicopathologic risk group, no. (%)
  Low140/224 (63)10 (50)130/204 (64)
  High84/224 (37)10 (50)74/204 (36)
Adjuvant chemotherapy, no. (%)
  Yes52 (23)6 (30)46 (22)
  No178 (77)14 (70)164 (78)

*There were no significant differences between the groups in any of the characteristics listed in this table.

†Right-sided colon cancer was defined as tumors arising from the cecum, ascending, hepatic flexure, or transverse colon; left-sided colon cancer was defined as tumors arising from the splenic flexure, descending, sigmoid, or rectosigmoid colon.

‡Except for two cases where oxaliplatin-based chemotherapy was used, all other adjuvant treatment was fluorouracil-based chemotherapy.