Relationship between postoperative tumor recurrence time and long-term survival in colorectal cancer patients

Table 1 Comparison of general clinical data between groups, n (%)

Clinical characteristics	Early recurrence group (n = 63)	Late recurrence group (n = 57)	Statistical value	P value
Gender			χ² = 0.046	0.831
Male	38 (60.3)	33 (57.9)
Female	25 (39.7)	24 (42.1)
Age (years, mean ± SD)	62.4 ± 11.3	59.7 ± 10.8	t = 1.338	0.183
BMI (kg/m², mean ± SD)	23.6 ± 3.2	24.1 ± 3.5	t = 0.892	0.374
Smoking history	24 (38.1)	19 (33.3)	χ² = 0.302	0.583
Drinking history	17 (27.0)	13 (22.8)	χ² = 0.286	0.593
Family history of CRC	8 (12.7)	6 (10.5)	χ² = 0.151	0.698
Comorbidities
Hypertension	23 (36.5)	18 (31.6)	χ² = 0.521	0.470
Diabetes	11 (17.5)	9 (15.8)	χ² = 0.338	0.561
Coronary heart disease	6 (9.5)	4 (7.0)	χ² = 0.245	0.621
ASA classification			χ² = 0.428	0.807
I-II	51 (81.0)	48 (84.2)
III	12 (19.0)	9 (15.8)
Tumor location			χ² = 0.228	0.633
Colon cancer	36 (57.1)	35 (61.4)
Rectal cancer	27 (42.9)	22 (38.6)

ASA: American Society of Anesthesiologists; BMI: Body mass index; CRC: Colorectal cancer.

Table 2 Comparison of tumor pathological characteristics between groups, n (%)

Pathological characteristics	Early recurrence group (n = 63)	Late recurrence group (n = 57)	Statistical value	P value
Tumor size (cm, mean ± SD)	4.8 ± 1.6	4.5 ± 1.4	t = 1.125	0.263
Tumor invasion depth			χ² = 2.847	0.092
T1-T2	8 (12.7)	13 (22.8)
T3-T4	55 (87.3)	44 (77.2)
TNM staging			χ² = 4.082	0.043
Stage II	15 (23.8)	23 (40.4)
Stage III	48 (76.2)	34 (59.6)
Lymph nodes dissected (n, mean ± SD)	16.3 ± 5.8	17.2 ± 6.1	t = 0.834	0.406
Positive lymph nodes (n, mean ± SD)	3.2 ± 2.7	2.4 ± 2.3	t = 1.724	0.087
Histological differentiation			χ² = 6.253	0.012
Well-moderate	42 (66.7)	49 (86.0)
Poor	21 (33.3)	8 (14.0)
Vascular invasion			χ² = 7.476	0.006
Negative	30 (47.6)	41 (71.9)
Positive	33 (52.4)	16 (28.1)
Neural invasion			χ² = 5.192	0.023
Negative	39 (61.9)	46 (80.7)
Positive	24 (38.1)	11 (19.3)
Pre-operative CEA level			χ² = 3.863	0.049
< 5 ng/mL	18 (28.6)	26 (45.6)
≥ 5 ng/mL	45 (71.4)	31 (54.4)
Pre-operative CA19-9 level			χ² = 2.156	0.142
< 37 U/mL	41 (65.1)	43 (75.4)
≥ 37 U/mL	22 (34.9)	14 (24.6)

CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9.

Table 3 Comparison of post-operative adjuvant treatment between groups, n (%)

Treatment parameters	Early recurrence group (n = 63)	Late recurrence group (n = 57)	Statistical value	P value
Received adjuvant chemotherapy			χ² = 0.033	0.856
Yes	58 (92.1)	53 (93.0)
No	5 (7.9)	4 (7.0)
Chemotherapy regimen	n = 58	n = 53	χ² = 0.215	0.643
FOLFOX	36 (62.1)	31 (58.5)
XELOX	22 (37.9)	22 (41.5)
Chemotherapy cycles (mean ± SD)	6.7 ± 1.6	6.9 ± 1.5	t = 0.723	0.471
Completed standard chemotherapy	n = 63	n = 57	χ² = 0.300	0.584
Yes (6-8 cycles)	46 (73.0)	44 (77.2)
No (< 6 cycles)	17 (27.0)	13 (22.8)
Chemotherapy adverse reactions	n = 58	n = 53	χ² = 0.158	0.691
≥ Grade 3	14 (24.1)	11 (20.8)
< Grade 3	44 (75.9)	42 (79.2)
Neoadjuvant chemoradiotherapy for RC	n = 27	n = 22	χ² = 0.000	0.988
Received	11 (40.7)	9 (40.9)
Not received	16 (59.3)	13 (59.1)
Post-operative radiotherapy for RC	n = 27	n = 22	χ² = 0.074	0.785
Received	9 (33.3)	8 (36.4)
Not received	18 (66.7)	14 (63.6)
Surgical approach			χ² = 0.186	0.666
Open surgery	37 (58.7)	31 (54.4)
Laparoscopic surgery	26 (41.3)	26 (45.6)

Denominators for chemotherapy regimen and adverse reactions are patients receiving adjuvant chemotherapy. Denominators for rectal cancer-related treatments are rectal cancer patients (27 in early recurrence group, 22 in late recurrence group). FOLFOX: Oxaliplatin + leucovorin + 5-fluorouracil; XELOX: Oxaliplatin + capecitabine; RC: Rectal cancer.

Table 4 Analysis of recurrence patterns and sites between groups, n (%)

Recurrence characteristics	Early recurrence group (n = 63)	Late recurrence group (n = 57)	Statistical value	P value
Recurrence pattern			χ² = 4.673	0.097
Local recurrence only	12 (19.0)	18 (31.6)
Distant metastasis only	38 (60.3)	31 (54.4)
Combined local and distant	13 (20.6)	8 (14.0)
Distant metastasis sites
Liver metastasis	34 (54.0)	26 (45.6)	χ² = 0.863	0.353
Lung metastasis	20 (31.7)	13 (22.8)	χ² = 1.226	0.268
Peritoneal metastasis	11 (17.5)	8 (14.0)	χ² = 0.278	0.598
Bone metastasis	5 (7.9)	3 (5.3)	χ² = 0.349	0.555
Lymph node metastasis	9 (14.3)	6 (10.5)	χ² = 0.409	0.522
Brain metastasis	2 (3.2)	1 (1.8)	χ² = 0.267	0.605
Number of metastatic organs			χ² = 3.428	0.180
Single organ	32 (50.8)	35 (61.4)
Multiple organs (≥ 2)	19 (30.2)	12 (21.1)
Local recurrence only	12 (19.0)	10 (17.5)
Recurrence detection method			χ² = 1.865	0.393
Imaging examination	48 (76.2)	47 (82.5)
Tumor marker elevation	11 (17.5)	7 (12.3)
Clinical symptoms	4 (6.3)	3 (5.3)
Tumor markers at recurrence
CEA ≥ 5 ng/mL	50 (79.4)	34 (59.6)	χ² = 5.705	0.017
CEA level (ng/mL, median)	18.6 (6.3-45.2)	9.8 (3.7-28.5)	Z = 2.315	0.021
CA19-9 ≥ 37 U/mL	28 (44.4)	19 (33.3)	χ² = 1.592	0.207
Time to diagnosis (months, mean ± SD)	2.8 ± 1.6	3.2 ± 1.8	t = 1.289	0.200

Values in parentheses after median represent interquartile range. CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9.