Statistical analysis of clinical baseline data
This study included 94 colorectal cancer patients with chronic schistosomiasis (CRCS+) who underwent surgery at Xiangya Hospital of Central South University between January 1, 2014 and December 31, 2019. Analysis of patient residence showed that all but two patients (who lived along the Yangtze River in Jingzhou City, Hubei Province) lived in Dongting Lake and its tributaries, including 43 patients in Yueyang City, 24 in Yiyang City, 17 in Changde City, 5 in Changsha City, 2 in Yongzhou City, and 1 in Hengyang City, Hunan Province. All patients had a history of contact with schistosomiasis water. The distribution of patients is shown in Fig. 1.
According to TNM stage, 17 CRCS+ patients (18.1%) were stage I; 41 (43.6%) were stage II; 32 (34.0%) were stage III; and 4 (4.3%) were stage IV. By tumor location, 47 cases (50.0%) were rectal cancer; 16 (17.0%) were sigmoid colon cancer; 7 (7.4%) were left colon cancer; and 24 (25.5%) were right colon cancer.
A total of 6025 colorectal cancer patients without schistosomiasis who met the inclusion and exclusion criteria and underwent surgery at Xiangya Hospital of Central South University between January 1, 2014 and December 31, 2019 were included in this study. Of these patients, 782 (13.0%) were stage I; 2158 (35.8%) were stage II; 2525 (41.9%) were stage III; and 560 (9.3%) were stage IV. By tumor location, 3005 cases (49.9%) were rectal cancer; 1085 (18.0%) were sigmoid colon cancer; 504 (8.4%) were left colon cancer; 71 (1.2%) were transverse colon cancer; and 1360 (22.6%) were right colon cancer.
The proportion of CRCS+ patients at stages I and II (61.7%) was higher than that of patients without schistosomiasis (48.8%), although the difference was not statistically significant (P = 0.062). There was no significant difference in tumor location between CRCS+ patients and patients without schistosomiasis (P = 0.807). See Table 1.
Gender was compared between CRCS+ patients and the 6025 colorectal cancer patients without schistosomiasis. Among CRCS+ patients, there were 64 males (68.1%) and 30 females (31.9%). Among the 6025 patients without schistosomiasis, there were 3606 males (59.9%) and 2419 females (40.1%). The proportion of males was higher among CRCS+ patients, but the difference was not statistically significant (P = 0.106).
The age of CRCS+ patients ranged from 29 to 81 years, with an average age of 66.13 ± 9.23 years; among them, 79 cases (84.0%) were over 60 years old. In contrast, the age of colorectal cancer patients without schistosomiasis ranged from 14 to 92 years, with an average age of 58.35 ± 12.07 years; among them, 2973 cases (49.3%) were over 60 years old. The proportion of patients aged over 60 years was significantly higher in CRCS+ patients compared to patients without schistosomiasis (P < 0.001), as shown in Fig. 2.
Table 1
Comparison between CRCS+ patients and 6025 patients without schistosomiasis
Clinicopathological characteristics | CRCS+ | 6025 Colorectal cancer patients without schistosomiasis | P-value |
TNM | I | 17(18.1%) | 782(13.0%) | 0.062 |
II | 41(43.6%) | 2158(35.8%) |
III | 32(34.0%) | 2525(41.9%) |
IV | 4(4.3%) | 560(9.3%) |
Location | Rectum | 47(50.0%) | 3005(49.9%) | 0.807 |
Sigmoid colon | 16(17.0%) | 1085(18.0%) |
Left colon | 7(7.4%) | 504(8.4%) |
Right colon | 24(25.5%) | 1360(22.6%) |
Transverse colon | 0(0.0%) | 71(1.2%) |
Gender | male | 64(68.1%) | 3606(59.9%) | 0.106 |
female | 30(31.9%) | 2419(40.1%) |
Age | ≤ 50 | 5(5.3%) | 1568(26.0%) | P<0.001 |
51–60 | 11(11.7%) | 1670(27.7%) |
61–70 | 50(53.2%) | 1866(31.0%) |
71–80 | 24(25.5%) | 755(12.5%) |
≥ 81 | 4(4.3%) | 166(2.8%) |
CRCS+: colorectal cancer patients with chronic schistosomiasis |
To reduce potential confounding factors, propensity score matching was performed based on gender, age, tumor location, year of surgery, TNM stage, and preoperative chemotherapy. As a result, a total of 94 colorectal cancer patients without chronic schistosomiasis (CRCS−) were randomly matched in a 1:1 ratio. See Table 2.
Table 2
Comparison between CRCS+ and CRCS− patients after propensity score matching
Variable | CRCS+(N = 94) | CRCS−(N = 94) | P-value |
Gender | male | 64(68.1%) | 64(68.1%) | 1.000 |
female | 30(31.9%) | 30(31.9%) |
Age | 66.1 ± 9.23 | 65.6 ± 8.94 | 0.665 |
Year of operation | 2014 | 18(19.1%) | 13(13.8%) | 0.807 |
2015 | 16(17.0%) | 19(20.2%) |
2016 | 9(9.6%) | 13(13.8%) |
2017 | 16(17.0%) | 18(19.1%) |
2018 | 21(22.3%) | 20(21.3%) |
2019 | 14(14.9%) | 11(11.7%) |
Location | Rectum | 47(50.0%) | 48(51.1%) | 0.627 |
Sigmoid colon | 16(17.0%) | 21(22.3%) |
Left colon | 7(7.4%) | 5(5.3%) |
Right colon | 24(25.5%) | 19(20.2%) |
Transverse colon | 1(1.1%) | 1(1.1%) |
TNM | I | 17(18.1%) | 25(26.6%) | 0.308 |
II | 41(43.6%) | 40(42.6%) |
III | 32(34.0%) | 28(29.8%) |
IV | 4(4.3%) | 1(1.1%) |
Chemotherapy | yes | 10(10.6%) | 5(5.3%) | 0.178 |
no | 84(89.4%) | 89(94.7%) |
According to the patients' medical history, imaging data, and surgical records, 9 cases (9.6%) of CRCS+ patients had intestinal obstruction before surgery. Among CRCS− patients, 8 cases (8.5%) had intestinal obstruction before surgery, and there was no significant difference between the two groups (P = 0.799).
The preoperative colonoscopy reports revealed that 27 CRCS+ patients (28.7%) had multiple colon polyps (≥ 2). Similarly, 27 CRCS− patients (28.7%) had multiple colon polyps, and there was no significant difference observed between the two groups (P = 1.000).
Preoperative blood routine examination results were compared between CRCS+ and CRCS− patients; for patients with a history of chemotherapy, results before the first chemotherapy were taken into account. The blood routine indicators analyzed in this study included white blood cell count, red blood cell count, hemoglobin, platelet count, neutrophil count, lymphocyte count, eosinophil count, basophil count, monocyte count, neutrophil ratio, lymphocyte ratio, eosinophil ratio, basophil ratio, and monocyte ratio. The study found no significant difference in these blood routine examination results between the two patient groups. See Table 3.
Preoperative liver function results were compared between CRCS+ and CRCS− patients; for patients with a history of chemotherapy, results before the first chemotherapy were taken into account. The level of aspartate aminotransferase was significantly higher in CRCS+ patients than in CRCS− patients; the difference between the two groups was statistically significant (P = 0.047). However, no significant differences were observed in other liver function indicators such as total protein, albumin, globulin, total bilirubin, direct bilirubin, total bile acid, and alanine aminotransferase between the two groups. See Table 4.
In this study, 74 CRCS+ patients (78.7%) tested positive and 20 (21.3%) tested negative for fecal monoclonal occult blood test before surgery. Among CRCS− patients, 84 (89.4%) tested positive and 10 (10.6%) tested negative for fecal monoclonal occult blood before surgery. The difference was statistically significant (P = 0.046).
Table 3
Comparison of preoperative blood routine examination between CRCS+ and CRCS-
Variable | CRCS+ | CRCS- | P-value |
White blood cell count(10^9/L) | 6.25 ± 1.97 | 6.29 ± 1.77 | 0.907 |
Red blood cell count(10^12/L) | 4.17 ± 0.56 | 4.21 ± 0.55 | 0.633 |
Hemoglobin(g/L) | 120.48 ± 22.27 | 121.86 ± 22.04 | 0.669 |
Platelet(10^9/L) | 237.73 ± 114.03 | 227.46 ± 81.85 | 0.479 |
Neutrophil count(10^9/L) | 4.01 ± 1.64 | 3.93 ± 1.45 | 0.735 |
Lymphocyte count(10^9/L) | 1.53 ± 0.55 | 1.66 ± 0.62 | 0.126 |
Eosinophil count(10^9/L) | 0.18 ± 0.18 | 0.19 ± 0.13 | 0.852 |
Basophil count(10^9/L) | 0.02 ± 0.04 | 0.02 ± 0.04 | 0.865 |
Monocyte count(10^9/L) | 0.50 ± 0.20 | 0.48 ± 0.16 | 0.428 |
Neutrophil ratio(%) | 62.92 ± 9.50 | 61.72 ± 8.31 | 0.355 |
Lymphocyte ratio(%) | 25.47 ± 8.85 | 26.90 ± 8.12 | 0.251 |
Basophil ratio(%) | 0.55 ± 0.34 | 0.61 ± 0.43 | 0.229 |
Eosinophil ratio(%) | 2.90 ± 2.18 | 3.12 ± 2.23 | 0.501 |
Monocyte ratio(%) | 8.11 ± 2.22 | 7.66 ± 1.65 | 0.113 |
CRCS+: colorectal cancer patients with chronic schistosomiasis CRCS-༚colorectal cancer patients without chronic schistosomiasis
Table 4
Comparison of preoperative liver function results between CRCS+ and CRCS-
Variable | CRCS+ | CRCS- | P-value |
Total protein(g/L) | 66.17 ± 6.63 | 67.74 ± 6.14 | 0.093 |
Albumin(g/L) | 39.04 ± 5.05 | 39.99 ± 4.63 | 0.177 |
Globulin(g/L) | 27.13 ± 4.36 | 27.75 ± 3.92 | 0.308 |
Total bilirubin (µmol/L) | 9.97 ± 4.36 | 9.64 ± 4.40 | 0.604 |
Direct bilirubin(µmol/L) | 4.25 ± 1.94 | 3.98 ± 1.87 | 0.333 |
Total bile acid(µmol/L) | 5.68 ± 6.78 | 4.73 ± 4.27 | 0.255 |
Alanine aminotransferase(U/L) | 19.35 ± 13.57 | 16.45 ± 8.49 | 0.081 |
Aspartate aminotransferase(U/L) | 23.53 ± 9.86 | 21.14 ± 6.06 | 0.047 |
CRCS+: colorectal cancer patients with chronic schistosomiasis CRCS-༚colorectal cancer patients without chronic schistosomiasis
Blood type was compared between the two groups. Among CRCS+ patients, there were 31 cases (33.0%) with blood type A, 26 (27.7%) with blood type B, 24 (25.5%) with blood type O, and 13 (13.8%) with blood type AB. Among CRCS− patients, there were 33 cases (35.1%) with blood type A, 15 (16.0%) with blood type B, 39 (41.5%) with blood type O, and 7 (7.4%) with blood type AB. The difference between the two groups was statistically significant (P = 0.039). See Table 5.
Table 5
Comparison of blood type between CRCS+ and CRCS-
Variable | CRCS+ | CRCS- | P-value |
Blood type | A | 31(33.0%) | 33(35.1%) | 0.039 |
B | 26(27.7%) | 15(16.0%) |
O | 24(25.5%) | 39(41.5%) |
AB | 13(13.8%) | 7(7.4%) |
CRCS+: colorectal cancer patients with chronic schistosomiasis CRCS-༚colorectal cancer patients without chronic schistosomiasis
Preoperative tumor marker results were compared between CRCS+ and CRCS− patients; for patients with a history of chemotherapy, results before the first chemotherapy were taken into account. This study compared CA125, CA199, CEA, and AFP levels but found no significant difference between the two groups. See Table 6.
Table 6
Comparison of preoperative tumor markers between CRCS+ and CRCS-
Variable | CRCS+ | CRCS- | P-value |
CA125 | 8.52 ± 6.47 | 7.22 ± 5.99 | 0.155 |
CA199 | 22.47 ± 55.78 | 15.94 ± 24.31 | 0.299 |
CEA | 10.74 ± 20.72 | 14.03 ± 50.10 | 0.558 |
AFP | 2.32 ± 1.98 | 2.00 ± 1.29 | 0.186 |
CRCS+: colorectal cancer patients with chronic schistosomiasis CRCS-༚colorectal cancer patients without chronic schistosomiasis
This study found that 18 CRCS+ patients (19.1%) had intestinal calcification on preoperative CT images while none of the CRCS− patients had intestinal calcification on preoperative CT images; the difference between the two groups was statistically significant (P < 0.001). See Fig. 3.
By reviewing preoperative CT imaging data, this study found that 6 CRCS+ patients had preoperative cirrhosis while none of the CRCS− patients had preoperative cirrhosis. Further analysis of blood routine examination and CT imaging was performed to compare whether the two groups of patients had portal hypertension before surgery. The main indicators were: 1) splenomegaly, with spleen long axis > 10cm and thickness diameter > 4.5cm; 2) preoperative white blood cell count < 4×109/L or platelet count < 100×109/L; 3) CT showing esophageal or gastric fundus varices; 4) portal vein width > 14mm or splenic vein width > 10mm. Patients meeting two or more criteria were diagnosed with portal hypertension. In this study, 2 CRCS+ patients were diagnosed with portal hypertension while none of the CRCS− patients were diagnosed with portal hypertension. Further comparison of Child-Pugh scores between the two groups showed that among CRCS+ patients, 87 had Child-Pugh grade A, 7 had grade B, and 0 had grade C. Among CRCS− patients, 86 had Child-Pugh grade A, 8 had grade B, and 0 had grade C. There was no significant difference between the two groups (P = 0.788). See Table 7.
Table 7
Comparison of preoperative liver profile between CRCS+ and CRCS-
Variable | CRCS+ | CRCS- | P-value |
Cirrhosis | 6 | 0 | 0.013 |
Portal hypertension | 2 | 0 | 0.155 |
Child-Pugh score | Child-Pugh A | 87 | 86 | 0.788 |
Child-Pugh B | 7 | 8 |
Child-Pugh C | 0 | 0 |
CRCS+: colorectal cancer patients with chronic schistosomiasis CRCS-༚colorectal cancer patients without chronic schistosomiasis