Table 1 Patient demographics and baseline information

Number of patients

73

Males

41 (56 %)

Females

32 (44 %)

Mean age, years (range)

65 (44–86)

Adenocarcinoma localization

 Caecum

6 (8 %)

 Caecum and ascending colon

1 (≈1 %)

 Ascending colon

4 (5 %)

 Transverse colon

5 (7 %)

 Descending colon

1 (≈1 %)

 Sigmoid colon

13 (18 %)

 Rectum

43 (59 %)

Primary tumor, pathological stage

 T1

5 (7 %)

 T2

11 (15 %)

 T3

39 (53 %)

 T4

16 (22 %)

 TX

2 (3 %)

Lymph node involvement, pathological stage

 N0

41 (56 %)

 N1

18 (25 %)

 N2

13 (18 %)

 NX

1 (≈1 %)

Neoadjuvant therapy

 No

61 (84 %)

 Yes

12 (16 %)

Adjuvant chemotherapy

 No

51 (70 %)

 Yes

22 (30 %)

Time since last curative surgery and PET/CT scan

 <6 months

7 (10 %)

 6–12 months

10 (14 %)

 12–18 months

16 (22 %)

 18–24 months

14 (19 %)

 24–36 months

14 (19 %)

 >36 months

12 (16 %)

Time since last postoperative imaging and PET/CT scan

 <3 months

22 (30 %)

 3–6 months

14 (19 %)

 6–12 months

15 (21 %)

 >12 months

12 (16 %)

 No postoperative imaging

10 (14 %)

Last postoperative imaging modality before PET/CT scan

 CT

55 (75 %)

 MRI

4 (5 %)

 PET/CT (not due to increasing CEA)

4 (5 %)

 No postoperative imaging

10 (14 %)

CEA subgroups

 1 increase in CEA

30 (41 %)

 2 consecutive increases in CEA

26 (36 %)

 >2 consecutive increases in CEA

5 (7 %)

 Persistently elevated CEA

12 (16 %)