Introduction
Colorectal cancer (CRC) is the third most common cancer in men and women, and the second leading cause of cancer-related mortality worldwide1,2. In Mexico, it is the third most common cancer and the second leading cause of mortality, according to data from Globocan 20203. Up to 20% of patients present with metastasis at diagnosis, and 25% of patients with localized disease will develop metastasis later on3. The 5-year survival rate for the localized stage is 91%, if the cancer has spread to surrounding organs or tissues, the 5-year survival rate is 72%. If the cancer has spread to distant parts of the body, the survival rate is 15%4. There is a higher incidence rate in men versus women regardless of age group.
Up to one-third of CRC cases are located in the rectum5. Surgical resection remains the only curative treatment for locoregional CRC6. In patients with late-stage III metastasis, pre-operative chemotherapy, and post-operative adjuvant chemotherapy are added to the management, and in more advanced stages, palliative treatment is opted for. Candidates for immunotherapy are those patients with CRC who have genetic mutations different from those inherited (microsatellite instability)7.
Sphincter-preserving surgical management is preferred. Laparoscopic cancer resection is as safe as open surgery, but its contraindications are obesity, previous abdominal surgeries, and advanced stages8,9.
The technique of total mesorectal excision is associated with lower local recurrence versus conventional blunt dissection; therefore, it is considered the surgical technique of choice for rectal cancer8.
The most common complications, after surgical treatment, are surgical site infections, hematomas, ileus, bowel obstruction, anastomotic dehiscence, cardiorespiratory, urinary, vascular complications, and among others10.
There are predictive factors for complications and anastomotic leakage after colorectal surgery such as age > 70 years11, pre-operative albumin levels, surgical time longer than 120 min, peritoneal contamination, intraoperative blood loss > 200 mL or 300 mL, intraoperative transfusions. Comorbidities that predict anastomotic leakage after surgery include congestive heart failure, peripheral vascular disease, alcoholism, steroid use, weight loss, and sodium imbalance12.
Malnutrition increases perioperative morbidity and mortality. In addition, certain organ functions will be altered depending on the techniques employed and the systems they affect13.
There are different scales to assess nutritional status, one of which is the Control Nutritional (CONUT) score. It is based on levels of albumin, total cholesterol, and absolute lymphocyte count, providing sensitivity, and specificity in detecting malnutrition. This scale has been used as a predictor of severity and mortality in GI tumors and as a prognostic factor in patients undergoing surgery for CRC14. However, there is not enough literature on the use of the CONUT scale as a predictor of complications and mortality in patients undergoing surgery for CRC15.
The objective of this study was to evaluate the Control Nutritional (CONUT) score in predicting post-operative anastomotic complications in patients with CRC.
Materials and methods
We comparative, cross-sectional, retrospective, homodemic, and correlational study at a tertiary referral center of the Mexican Social Security Institute in Puebla, Mexico.
Records of patients older than 18 years with CRC who underwent intestinal anastomosis in this unit, with serum levels of albumin, cholesterol, and lymphocytes, were reviewed. Patients who were operated on outside the unit, with findings of synchronous tumors, treated with meritorious resection of intestinal diversion, were excluded from the study. Patients who did not complete the clinical and paraclinical study, those who died before surgery, or who did not obtain a surgical date within the study period were eliminated.
The CONUT scale was applied to the recruited patients with pre-operative paraclinicals, and then post-operative complications were reviewed within the first 24 h up to 7 days after surgery. Two groups were formed: Group 1 with a CONUT score of 5 or less, and Group 2 with a score > 5.
After surgery, early complications present during the first 24 h as well as the presence of pulmonary infections and hemorrhages were monitored. Intentional screening was performed for anastomotic leakage at 48-96 h post-surgery and for surgical site infection and anastomotic fistulas up to 7 days post-surgery.
Descriptive statistics was used, and the Chi-square test was applied for the association of complications and the CONUT scale. The phi coefficient was used for the correlation of surgical complications and the CONUT score. A p = 0.05 or less was considered statistically significant. Data were processed using SPSS software for IBM version 25.0.
This study was approved by the Mexican Social Security Institute Health Research Committee 2101 (registration R-2023-2101-099). Personal data were handled with strict confidentiality and exclusively for research purposes.
Results
Health records from 82 patients diagnosed with CRC from 2022 through 2023 were reviewed. Forty-nine patients who met the inclusion criteria were recruited. Twenty-three patients who did not have an anastomosis and underwent intestinal diversion were excluded, five were discarded for not having surgical intervention, and five more were eliminated for having died before the surgical procedure due to advanced disease stage.
Of the sample of 49 patients, 23 (47%) participants were women and 26 (53%) were men, with a mean age of 58 (± 12.5) years, the mean height of 160 cm (± 0.064), mean weight of 63 kg (± 12.5), and a mean BMI of 24.5 kg/m² (± 4.15).
Family history of malignant tumors was found in 12 (24%) patients (gastric cancer, endometrial cancer, breast cancer, and pharyngeal cancer), and family members with CRC in 8 (16.3%) patients. In 12 (24%) patients, a smoking history was recorded, and in 10 (20%) a history of alcoholism.
Comorbidities were reported in 22 (45%) patients, including 12 patients (54.5%) with Type 2 diabetes, 11 (50%) with hypertension, 2 (9%) with hypothyroidism, 2 (9%) with liver cirrhosis, 1 (4.5%) with vitiligo, and 1 (4.5%) with systemic lupus erythematosus; 11 (50%) had more than 1 comorbidity.
The anatomical location of CRC lesions is illustrated in Fig. 1. A predominance in the ascending colon was found.
Figure 1. Tumor location in patients diagnosed with CRC.
Based on the CONUT Scale, the risk of malnutrition was distributed as shown in table 1. The CONUT was dichotomized, obtaining 32 (65%) patients scores ≤ 5 (zero or mild risk of malnutrition) and 17 (35%) patients scores > 5 (moderate or severe risk).
Table 1. CONUT score in CRC patients (n = 49)
| Risk level | Frequency | Percentage |
|---|---|---|
| No risk | 12 | 24 |
| Mild | 20 | 41 |
| Moderate | 7 | 14 |
| Severe | 10 | 20 |
| Total | 49 | 100 |
The frequency of post-operative complications is illustrated in Fig. 2. The most common was anastomotic dehiscence (43%), manifested by tachycardia, pain at the surgical site, and signs of peritoneal irritation. This was followed by anastomotic fistula (with pain at the surgical site, peritoneal irritation, hemodynamic deterioration, and discharge of intestinal material from the wound) at 14%, and others (sigmoid volvulus, perforation, right ureter trauma, etc.) at 22%.
Figure 2. Percentage of complications in 49 patients with CRC.
The distribution of post-operative complications in patients with and without risk of malnutrition is illustrated in table 2. The differences were significant (p = 0.023). The correlation of anastomotic complications with the CONUT scale using the Phi coefficient obtained a rho of 0.327 (p = 0.022).
Table 2. Relationship between CONUT scale and post-operative complications
| Conut | Complications | Total | |
|---|---|---|---|
| Yes | No | ||
| ≤ 5 | 4 | 28 | 32 |
| > 5 | 7 | 10 | 17 |
| Total | 11 | 38 | 49 |
Discussion
The present study was conducted to evaluate the association of CONUT scale scores and anastomotic complications in CRC patients undergoing intestinal resection and anastomosis.
Risk factors associated with CRC include family history, personal history of inflammatory bowel disease and/or diabetes, lifestyle and dietary habits such as smoking, alcohol consumption, and consumption of smoked meat, as well as bacterial infections16. In this study, males predominated, which is consistent with international reports17. A family history of CRC and other types of cancer such as gastric cancer and breast cancer also predominated. Among comorbidities, diabetes was the most common.
Malnutrition is one of the main mechanisms leading to death in cancer patients due to tumor cachexia characterized by anorexia, asthenia, and weight loss with progressive loss of body tissues and inability to regulate normal metabolic and homeostatic mechanisms, leading to a gradual failure of vital functions18. Cancer patients with malnutrition who are not on treatment have a 2-5 times higher risk of death versus those who are not malnourished19.
The CONUT scale is a tool that assesses the risk of malnutrition in patients with CRC10 and considers laboratory test results including serum albumin, total cholesterol, and total lymphocyte count20. Serum albumin indicates nutritional status, severity, progression, and prognosis in CRC. Normal serum albumin levels in adults are 3. g/dL-5.0 g/dL; levels < 3.5 g/dL are termed hypoalbuminemia21. Hypocholesterolemia (serum levels < 25 g/dL) usually occurs late in prolonged malnutrition states22 and correlates with tumor progression as it reduces plasma concentration and caloric intake23. A total lymphocyte count of < 1500 cells is associated with protein-energy malnutrition, indicating the patient’s immunological status, and is associated with a worse prognosis due to an insufficient immune response20.
In this study, out of the sample of 49 patients, 20 had a mild risk and 17 had a moderate-to-severe risk of malnutrition. The most frequent anastomotic complications were anastomotic dehiscence followed by anastomotic fistulas.
Low CONUT scores are associated with better overall and disease-free survival24, and high scores with major complications and a higher risk of mortality25.
In this study, anastomotic complications (dehiscence and fistula) were significantly more frequent in the group of patients with high CONUT scores, and the correlation between CONUT results and complications was also significant. The differences in the frequency of complications between the high and low CONUT score groups are very small, most likely due to the lack of a larger sample size. The same applies to the barely moderate (but significant) correlation figure. This constitutes an area of opportunity for future studies.
Conclusions
A score < 5 on the CONUT scale is associated with a lower frequency of anastomotic complications in CRC patients undergoing intestinal resection and anastomosis.
Funding
The authors declare that they have not received funding.
Conflicts of interest
The authors declare no conflicts of interest.
Ethical Responsibilities
Protection of human and animal subjects. The authors declare that no experiments were performed on humans or animals for this study.
Confidentiality of data. The authors declare that no patient data appear in this article. Furthermore, they have acknowledged and followed the recommendations as per the SAGER guidelines depending on the type and nature of the study.
Right to privacy and informed consent. The authors declare that no patient data appear in this article.
Use of artificial intelligence for generating text. The authors declare that they have not used any type of generative artificial intelligence for the writing of this manuscript, nor for the creation of images, graphics, tables, or their corresponding captions.
