Complications Following Colorectal Cancer Surgery

Abstract

Postoperative complications following colorectal cancer surgery occur in approximately 50% of patients, resulting in increased healthcare expenses and a decline in quality of life. Complication classification systems are commonly used to assess and categorize these adverse events across various healthcare institutions. The widely used Clavien-Dindo system is effective in classifying complications based on their clinical severity, yet it does not provide insights into the underlying factors contributing to their occurrence. Another classification system, the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) surgical risk calculator, was developed to accurately predict complications and length of stay. Most current studies primarily focus on the prevention of complications, employing preoperative, intraoperative, and postoperative interventions. Factors such as surgical technique selection, fluid therapy, transfusion preferences, and mechanical bowel cleaning can all play a significant role in reducing the occurrence of complications. Furthermore, patient-associated factors such as age, gender, tumor location, and body mass index (BMI) also influence the likelihood of experiencing complications. Postoperative complications not only negatively impact short-term quality of life and healthcare costs but also have long-term implications on oncological outcomes. These complications can result in delays or discontinuation of chemotherapy, even in patients who have clear indications for systemic therapy.

1. Introduction

Postoperative complications in patients undergoing colorectal cancer surgery occur in approximately 50% of cases and have been found to be associated with increased rates of morbidity and mortality, elevated healthcare costs, and a decline in overall quality of life.

A study conducted in the United Kingdom examining complications following colorectal surgery revealed that the in-hospital mortality rate ranged from 1 to 6.5%, while mortality within 30 days ranged from 0.7 to 11.3%. Additionally, the study reported a morbidity rate between 26.4 and 54.5%. Similarly, a separate study conducted in the United States, with a comparable objective, observed a mortality rate of 3.9% after colorectal surgery, a general morbidity rate of 24.3%, and a severe morbidity rate of 11.4%.

2. Classification and prediction of complications

Most existing research focuses on the prevention of complications, and several classification systems have been developed for this purpose. Among these systems, the Clavien-Dindo classification system stands out as the most useful. This system allows for easy comparison of complications across different time periods within the same institution, as well as between different institutions. Furthermore, it enables the comparison of surgical and conservative treatments, standardized documentation of operations, and associated complications and facilitates meta-analysis. However, it is important to note that the Clavien-Dindo classification system does not assess pre-existing conditions and comorbidities, despite their significant role in the occurrence of complications. In the Clavien-Dindo classification, only five grades of postoperative complications are defined (Table 1). Another classification system that offers a different approach is the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) surgical risk calculator. This model is built using data from over 4.3 million operations in the ACS NSQIP database. The current Universal Risk Calculator can be used for any procedure, in most surgical subspecialties, while previously developed NSQIP-based risk calculators can only be used for individual procedures (e.g., colectomy, pancreatectomy, etc.). The primary goal of this system is to accurately predict the risk of complications and length of stay for patients. The NSQIP takes into consideration the impact of a patient’s comorbidities on the risk of postoperative complications. The calculator is online and accessible available at https://riskcalculator.facs.org/RiskCalculator/index.jsp.

Grade I	Any deviation from the normal postoperative course without the need for pharmacological treatment or surgical, endoscopic, and radiological interventions. Allowed therapeutic regimens are drugs as antiemetics, antipyretics, analgetics, diuretics, electrolytes, and physiotherapy. This grade also includes wound infections opened at the bedside.
Grade II	Requiring pharmacological treatment with drugs other than such allowed for grade I complications. Blood transfusions and total parenteral nutrition are also included.
Grade III	Requiring surgical, endoscopic, or radiological intervention
a	Intervention not under general anesthesia
b	Intervention under general anesthesia
Grade IV	Life-threatening complication (including CNS complications)* requiring IC/ICU management
a	Single organ dysfunction (including dialysis)
b	Multiorgan dysfunction
Grade V	Death of a patient
d	If the patient suffers from a complication at the time of discharge, the suffix “d” (for“disability”) is added to the respective grade of complication. This label indicates the need for a follow-up to fully evaluate the complication.

Table 1.

Classification of surgical complications.

*

Brain hemorrhage, ischemic stroke, sub-arrachnoidal bleeding, but excluding transient ischemic attacks. CNS, central nervous system; IC, intermediate care; ICU, intensive care unit.

2.1 Operative procedures in colorectal cancer and their effect on complications

The surgical techniques used in the management of colorectal malignancies can be categorized into three main types: open surgery, laparoscopic surgery, and robotic surgery. Recently, there has been a significant advancement in endoscopic interventions, leading to the inclusion of therapeutic endoscopic approaches as a distinct group in the treatment of colorectal malignancies.

Several publications have explored the impact of different surgical techniques on the occurrence of complications. Comparing open surgery to laparoscopic surgery, the latter has been found to offer several advantages, including smaller incision length, reduced blood loss, and decreased post-operative pain. However, it should be noted that, for larger tumors, laparoscopic surgery may be less effective due to limitations in traction, resulting in inadequate exploration [1].

Laparoscopic surgery is associated with reduced blood loss when compared to open surgery. This difference can be attributed to the implementation of a high-resolution camera system during laparoscopic procedures, which allows for enhanced visualization and the ability to thoroughly examine multiple anatomical areas.

The findings of the MRC CLASICC study indicated that patients who underwent laparoscopic surgery had a shorter hospital stay compared to those who had the open surgical approach. Furthermore, the study found no significant variation in the occurrence of complications among the two groups at both 30 days and 3 months post-surgery.

Various comparative effectiveness studies investigating the laparoscopic approach versus the open approach in colon surgery have consistently demonstrated that minimally invasive techniques yield better short-term outcomes.

3. Intraoperative complications

The complications observed during colorectal surgery can be identified as follows: bleeding, injury to the small intestine and colon, vascular injuries, ureter and bladder injury, seminal vesicle injury, vaginal injury, splenic injury, presacral bleeding, and pelvic nerve injury.

3.1 Presacral hemorrhage

Preservation of the presacral fascia during rectal mobilization is crucial in preventing such complications. In the event of a ruptured presacral vein, severe bleeding occurs; however, it can effectively be controlled through suturing or cauterization.

3.2 Splenic injury

Iatrogenic splenic laceration is a frequent occurrence in colorectal surgery, often seen during left colon mobilization. Typically, the injury is limited, manifesting as a capsular tear on the anterior and inner surface of the spleen’s lower pole, resulting from traction on the splenic ligaments or greater omentum. In instances where the greater omentum is pulled, the injury may extend to the splenic hilum. In the past, splenectomy was commonly performed in all types of splenic injuries; however, recent recommendations suggest prioritizing spleen preservation whenever feasible. To prevent bleeding caused by splenic capsule tears, local hemostatic agents or electrocoagulation can be employed. If uncertainty persists despite these measures, splenectomy remains the most appropriate procedure.

3.3 Ureter, bladder, and urethra injuries

Intraoperative iatrogenic urethral injuries can occur when pelvic anatomy is disrupted due to factors such as pelvic inflammation, previous surgical interventions, radiation therapy, or malignancy. The occurrence rate of iatrogenic ureteral injury in colorectal surgery ranges from 0.3 to 1.5%. However, only a small number of these injuries are actually identified during the surgical procedure itself. The suspicion of an injury can be confirmed through various diagnostic methods including intravenous pyelogram (IVP), retrograde injection of methylene blue, intravenous administration of methylene blue or indigo carmine, or the administration of contrast material through a ureteral catheter.

Timely recognition and repair of an injury significantly enhance the recovery process. Late diagnosis, on the other hand, leads to substantial morbidity and increases the likelihood of nephrectomy by seven times. In the context of colon surgeries, it is noteworthy that injuries to the left ureter are more prevalent compared to the right ureter.

Risk factors that contribute to bladder injury during colorectal surgery encompass a range of factors such as previous surgeries, radiation therapy, malignant infiltration, chronic infections, and inflammatory conditions. To diagnose such injuries radiologically, healthcare professionals typically utilize either a CT cystogram or a fluoroscopic cystogram. In cases where minor extraperitoneal injuries are identified, repair is necessary, and the condition can be effectively treated through a period of 7–14 days with foley catheter decompression.

Among intraoperative urologic injuries, damage to the urethra is considered the least common. This type of injury frequently arises during abdominoperineal resection procedures. Fistula or stricture formation is a typical complication associated with such injuries. To accurately locate the site of injury, medical professionals rely on various diagnostic methods including cystoscopy, retrograde urethrogram, examination under anesthesia, and CT scan with both oral and rectal contrast. The preferred approach for management involves a double primary repair utilizing absorbable sutures at the time of injury. Additionally, utilizing an omental flap or a local tissue flap may help reduce the likelihood of postoperative fistula development.

4. Postoperative complications

Postoperative complications can be classified into two categories based on their occurrence in the early or late postoperative period. Early and late complications are closely interconnected clinical parameters. The early postoperative period is associated with the development of anastomotic leakage, anastomotic bleeding, and stenosis, in addition to postoperative ileus. In the case of inflammatory bowel diseases, there is a higher prevalence of thromboembolism and portal vein thrombosis. In the early postoperative period, hollow organ injuries may present with symptoms. Furthermore, wound complications, surgical site infections, and perineal complications can also arise during this period. On the other hand, in the late postoperative period, one may encounter complications related to stomas. Peristomal infection and skin problems may manifest as early clinical symptoms during this period.

4.1 Ileus

Postoperative ileus refers to the transient loss of intestinal motor function that typically occurs after abdominal surgery. This response is triggered by the stimulation of splanchnic sympathetic nerves as a result of bowel manipulation during the surgical procedure. However, it can also be seen following surgery or trauma to other organs. Gastric atony, which is the loss of muscle tone in the stomach, usually resolves within one to 2 hours. The small intestine recovers its normal motor function within 1–2 days, while the large intestine takes approximately 2–3 days. It may take up to 5 days for the resumption of regular motor function in the intestines following postoperative ileus.

In the context of intra-abdominal infection, it is important to address the underlying cause in order to resolve persistent ileus. Symptoms such as fever, leukocytosis, and abdominal pain may suggest the presence of intra-abdominal infection or anastomotic leakage. To address this condition, certain measures should be implemented. These include the use of a nasogastric tube for decompression, suitable intravenous fluid replacement, administration of antiemetic and prokinetic agents, and correction of any electrolyte imbalances.

4.2 Bladder dysfunction

Bladder dysfunction is a frequently encountered issue that arises when the parasympathetic nerves responsible for innervating the detrusor muscle or the sympathetic nerves responsible for innervating the bladder neck, trigone, and urethra sustain damage during pelvic dissection. This condition can be further exacerbated by postoperative distension, prostatic hypertrophy, and pain. Following rectal dissection, bladder dysfunction has been observed to occur in approximately 20–30% of cases. However, it is important to note that the majority of patients gradually regain their bladder emptying capabilities, although this recovery process may take up to six months.

4.3 Sexual dysfunction

Sexual dysfunction can result from damage to the sympathetic and parasympathetic nerves in the pelvic region. Studies have reported a wide range of prevalence rates, with sexual dysfunction occurring in approximately 15–60% of cases. The parasympathetic erigentes nerves are responsible for the neurological impulse that triggers an erection, while the sympathetic nerves are involved in the neurological impulse for ejaculation. It is worth noting that female patients are generally less likely to experience sexual dysfunction in comparison to their male counterparts.

Here is evidence to suggest that sexual dysfunction following proctectomy may show spontaneous improvement within 6–12 months post-surgery. Additionally, the use of sildenafil has shown promising results in improving erectile dysfunction in approximately 80% of patients. Notably, the use of sildenafil may also contribute to reducing postoperative morbidity [2].

4.4 Fecal incontinence

Following an inferior anterior resection procedure, a small percentage of patients (approximately 5–6%) may experience the development of fecal incontinence, an increased number of bowel movements, and a decrease in the overall quality of life. The causes of anal sphincter dysfunction in these cases are multifactorial. Possible factors include damage to the sphincter caused by anastomotic staples applied through the anus or denervation of the pelvic muscles during rectal mobilization. However, it is important to note that these dysfunctions have the potential to improve within one-year post-surgery.

4.5 Femoral and peroneal neuropathies

Automatic retractors have been identified as a common cause of femoral neuropathies. The reported incidence of femoral neuropathy following colon resection is approximately 0.7%. The femoral nerve, as the largest branch of the lumbar plexus, can potentially be injured during the passage through the psoas muscle. Patients experiencing this condition may present with symptoms such as weakness of the quadriceps femoris, reduced or absent patellar tendon reflexes, and hypoesthesia of the anteromedial thigh. However, the prognosis for femoral neuropathy is generally positive, with over 90% of patients showing recovery through the implementation of physical therapy.

4.6 Thromboembolism

The occurrence rate of thromboembolic events typically ranges from 1 to 7%. Although many deep vein thromboses do not show symptoms, they can occasionally progress to pulmonary embolism, which carries the risk of fatality. Findings from various randomized trials indicate that the preventive measures for deep vein thrombosis include the use of low molecular weight heparin, elastic stockings or bandages, and early mobilization.

4.7 Myocardial ischemia/infarction

The clinical manifestation occurs when an imbalance arises between the oxygen demand and myocardial oxygenation. The etiology can be categorized into two main aspects: conditions that increase oxygen demand (e.g., anemia, hypoxemia, hypotension, fever, tachycardia, surgical stress, etc.) and conditions that restrict perfusion (e.g., atherosclerosis, vasospasm, etc.). This clinical presentation is associated with significant mortality and morbidity in the postoperative period and is considered one of the primary causes of post-surgical death. The presence of risk factors such as underlying diabetes mellitus, smoking, advanced age, and family history are indications of a poor prognosis.

4.8 Arrhythmia

Arrhythmia is frequently observed in patients with a cardiac disease history. It can be classified into three main categories: tachyarrhythmias, bradyarrhythmias, and blocks. Common presenting symptoms include palpitations, chest pain, shortness of breath, hypotension, and syncope. Typically, arrhythmias are transient in nature, and it is crucial to investigate and identify the underlying causes while prioritizing hemodynamic stability.

4.9 Pneumonia

Predisposing factors for pneumonia include chronic lung diseases, smoking, and atelectasis. Patients with this condition often experience symptoms such as fever, tachypnea, and tachycardia. Aspiration pneumonia is particularly a concern for patients who undergo emergency surgery without a prior fasting period and those with intestinal obstruction. Unfortunately, the mortality rate for aspiration pneumonia exceeds 50%.

4.10 Anastomotic complications

4.10.1 Anastomotic leakage

Anastomotic leakage commonly manifests within the 5–7-day postoperative period. Clinical follow-up may reveal fever, leukocytosis, tachypnea, hypotension, localized or diffuse tenderness, ileus, tachycardia, and distension as potential findings. Early leaks are associated with high morbidity.

In large series, the intra-abdominal leak rate ranges from 1 to 5%. However, when it comes to anastomoses in the pelvis, the leak rate is higher, ranging from 5 to 15%.

4.10.2 Bleeding from the anastomotic line

Bleeding from the anastomosis line is uncommon and usually self-limiting. However, in cases where the patient has a bleeding diathesis, it is important to correct this condition. If the bleeding persists and worsens clinically, it can be managed by placing sutures near the anal canal to control the bleeding. In the case of anastomoses in the high-level region, if bleeding cannot be successfully stopped, it may be necessary to perform a relaparotomy.

4.10.3 Anastomotic stenosis/stricture

Anastomotic stricture can be caused by various factors including ischemia, anastomotic leakage, the use of narrow staplers, radiotherapy, and proximal diversion. Stenosis in the rectum can be treated by methods such as rectal examination, surgical intervention, or balloon dilatation. On the other hand, stenosis in colonic anastomoses is less common. In large series, the rate of stenosis in rectal anastomoses is reported to be around 20%, while it is lower at approximately 1–2% in colonic anastomoses.

4.11 Stoma complications

4.11.1 Stoma ischemia and necrosis

Ischemia and necrosis occur more frequently in colostomies, particularly when the left colic artery is ligated, compared to ileostomies. An ischemic stoma can be identified by its pale, edematous, or grayish blue color. Without sufficient blood flow, the ischemic stoma can progress to necrosis over time. Consequently, it is crucial to closely observe the color of the stoma during the initial 24–48 hours following the surgery. Stoma ischemia can be caused by a narrow opening in the abdominal wall or a taut stoma opening.

4.11.2 Stoma retraction

Stoma retraction refers to the protrusion of the stoma into the abdominal cavity. While it typically occurs in the early stages, it can also manifest later on. Inadequate mobilization and fixation of the colon, as well as obesity, are contributing factors to stoma retraction. In some cases, surgical revision may be necessary to address this issue.

4.11.3 Stoma prolapse

Stoma prolapse refers to the outward protrusion of the stoma from the abdominal wall. In terms of functionality, stoma prolapse does not typically pose significant implications for the patient. This complication usually arises in the later stages following the surgery. The risk of stoma prolapse is greater in ostomies created from the transverse colon, ostomies with a wide opening that is inadequately secured to the abdominal wall, patients with weak abdominal fascia, and elderly individuals. Mild cases of prolapse can often be managed through manual reduction.

4.11.4 Stoma obstruction

Stoma obstruction commonly occurs in the later stages following the surgery. In the case of ileostomies, intestinal adhesion, volvulus, and stoma stenosis are among the factors contributing to obstruction. Specifically, obstruction caused by food intake is most frequently observed during the third and sixth months following the surgery for ileostomy patients. As for colostomies, causes of obstruction can include stenosis or parastomal hernia. Additionally, tumor recurrence and hardened stool are also potential factors leading to colostomy obstruction.

4.12 Wound site infection

Infection in the surgical wound typically occurs on the third or fourth day following the operation. Clinical indications of infection encompass erythema, stiffness, edema, enlargement, and elevated temperature in the wound area. The puncture or opening of the wound may yield purulent, hemopurulent, or seropurulent discharge. If left untreated, wound infection can lead to wound dehiscence. Treatment options usually involve drainage and administration of antibiotherapy.

5. Impact of perioperative interventions on complications

The extensive research and debate surrounding the role of mechanical bowel preparation in preventing surgical site infections is an ongoing topic of interest in the medical field. However, the existing data on this subject are often conflicting, and arguments for or against bowel preparation tend to be driven by personal preference rather than strong evidence.

There are limited available data regarding the use of oral antibiotic preparation without mechanical bowel cleansing. A study published in 2017 utilized data from the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) to compare different patient groups. Among the 14,080 patients included in the study, 1461 received only oral antibiotics, 9800 received mechanical bowel cleansing, and 8819 received both oral antibiotics and mechanical bowel cleansing. When comparing the group that received oral antibiotics alone with the group that underwent mechanical bowel cleansing, several outcomes were assessed. These included surgical site infection, anastomotic leakage, postoperative ileus, and major morbidity after colorectal surgery. Interestingly, the study found that the group receiving oral antibiotics alone had decreased rates of these complications compared to the group that underwent mechanical bowel cleansing. Based on these findings, the study suggests that the addition of mechanical bowel cleansing may not be necessary in the context of oral antibiotic administration. However, it is important to note that this study is retrospective and utilized data from a national database. Therefore, it is recommended that further research, specifically randomized controlled trials, be conducted to provide a more definitive understanding of this issue.

There are several skin preparation techniques and products that exist for colorectal procedures; however, a clear consensus regarding their efficacy is currently lacking. A randomized controlled trial revealed that the utilization of chlorhexidine-alcohol, as opposed to povidone-iodine, resulted in a notable reduction of both superficial surgical site infections and deep incisional infections.

The implementation of an active heating strategy perioperatively has been demonstrated to decrease surgical site infections in patients undergoing colorectal surgery.

The PROXI study evaluated whether the administration of 80% oxygen during anesthesia in individuals undergoing abdominal surgery is effective in reducing the occurrence of surgical site infections, while ensuring that the incidence of pulmonary complications remains unaffected. Prior research has proposed that the use of 80% oxygen during surgery may decrease the likelihood of surgical wound infections, but the results have not been uniformly established. Moreover, the impact of 80% oxygen on pulmonary complications remains poorly understood.

6. The effect of post-operative interventions on complications

The incorrect administration of intravenous fluids has been identified as a contributing factor to postoperative complications. A study indicated that patients who received restricted fluids experienced earlier return of bowel function, shorter hospital stays, and lower rates of complications.

The findings of a meta-analysis of randomized controlled trials reveal that patients who were treated with the Enhanced Recovery After Surgery (ERAS) protocol, which includes fluid restriction, experienced significant benefits compared to those receiving standard postoperative care. Specifically, the patients in the ERAS group had an average shorter length of stay by 2.5 days and a 50% lower rate of postoperative morbidity.

Perioperative pain is recognized as a potent stimulus for the stress response, which can induce activation of the autonomic nervous system and subsequently lead to negative postoperative outcomes. While it remains uncertain whether inadequate pain control directly contributes to complications, many surgeons have embraced the principle of ensuring effective pain management as part of their postoperative care protocol.

According to a recently published meta-analysis, it was concluded that while there was an improvement in pain control with the use of epidurals in patients undergoing laparoscopic colectomy, there was no significant difference observed in terms of the return of bowel function or the length of hospital stay.

Postoperative recovery protocols in academic journals have predominantly integrated non-opioid-based pain regimens. Various studies have also emphasized the utilization of local blocks, such as the transversus abdominis plane (TAP) block, with the aim of enhancing pain management.

Intraoperative contamination poses a risk of infection, with wound hematoma or seroma acting as a potential trigger. A study involving 76 patients with high-risk wounds examined the impact of daily negative pressure wound dressing compared to standard wound treatment. The results revealed that patients treated with daily negative pressure wound dressing had lower rates of surgical site infection. Implementing this technique on contaminated wounds can effectively reduce the incidence of surgical site infections. It is worth noting that this approach is minimally invasive and may potentially lead to shorter hospital stays.

7. Factors affecting complications

Age is recognized as an independent risk factor for both morbidity and mortality, surpassing the impact of other comorbidities [3]. Elderly patients often face a higher degree of challenges regarding their ability to tolerate surgical procedures, surpassing those experienced by other age groups. Moreover, the elderly population encounters additional issues specific to their age group, including cognitive impairment and a potential lack of social support.

Studies have demonstrated a link between cognitive impairment and an increased need for higher levels of care in the older adult population. Specifically, it has been found that preoperative cognitive impairment, regardless of age, is associated with a higher likelihood of experiencing postoperative complications, an extended length of hospital stay, and a higher six-month mortality rate.

Frailty is a syndrome characterized by age-related declines in functional reserves across various physiological systems. The presence of negative energy and nutritional imbalances exacerbates frailty, thereby prolonging postoperative care for affected patients.

Obesity poses several challenges during surgical procedures, including increased technical complexity and potentially longer duration. Additionally, it significantly elevates the risk of developing wound site infections. A study conducted by Itani et al. explored the connection between body mass index (BMI) and antibiotic prophylaxis among patients undergoing elective colorectal surgery. The findings revealed a higher incidence of surgical site infections among patients with a BMI above 30 kg/m², irrespective of the type of prophylaxis employed [4]. Another study by Yamamoto et al. identified BMI as an independent risk factor for the development of anastomotic leakage [5]. However, BMI alone fails to encompass the full risk of obesity-related wound infections, leading to recent investigations into the role of waist circumference (WC) and waist-to-hip ratio (WHR) in perioperative outcomes. A prospective, multicenter, international study involving 1349 patients undergoing elective colorectal surgery was carried out to evaluate the impact of WC and WHR on surgical complications. The results demonstrated that increased WHR independently predicted intraoperative complications, medical complications, and reinterventions, whereas increased BMI was only associated with abdominal wall complications.

Minimally invasive surgery offers the advantage of reduced blood loss and a lower rate of blood transfusion compared to traditional open surgery. Research studies have consistently reported that perioperative blood transfusions can have detrimental effects on patient survival, and patients who receive transfusions are more likely to experience postoperative complications [6, 7]. It is worth noting that the administration of allogeneic blood transfusions is also a well-known risk factor for surgical site infections.

The American Society of Anesthesiologists (ASA) classification system is utilized to evaluate and categorize patients prior to surgery. This classification helps determine the appropriate anesthetic approach and monitoring methods for each patient. Longo et al. conducted a study examining the factors contributing to early mortality and morbidity among patients undergoing colectomy. Their findings revealed that patients classified as ASA 3, 4, and 5 exhibited higher rates of early mortality and complications [8].

Previous research has established a connection between diabetes mellitus and a greater risk of experiencing complications related to surgical site infection. Specifically, inadequate glucose regulation has been linked to a heightened likelihood of early postoperative surgical site infection in individuals undergoing colorectal surgery.

The location of a tumor plays a role in the occurrence of complications. Studies have demonstrated that rectal tumors are more prone to developing anastomotic leakage when compared to tumors located in the colon.

In a study conducted by Hamabe et al., the correlation between neoadjuvant chemotherapy and anastomotic leakage was investigated. The results indicated that the risk of experiencing anastomotic leakage was 3.5 times greater in patients who received neoadjuvant chemotherapy, as determined through multivariate analysis [9].

As the size of a tumor increases, there are limitations on intrapelvic manipulation, and the process of rectal transection becomes more challenging. Consequently, tumor size has been identified as a potential risk factor for anastomotic leakage. In a study comprising 154 rectal cancer patients, findings revealed a four-fold increased risk of anastomotic leakage in tumors that were equal to or larger than 5 cm in diameter [10].

According to existing literature, it has been noted that there is a higher incidence of anastomotic leakage following colorectal surgery among male patients. This observation has been attributed to potential technical challenges arising from the narrower pelvis in male individuals.

Considerable attention has been devoted to investigating the influence of surgical volume on the occurrence of complications. The relationship between the volume of surgeons and that of the medical institutions involved may be intricately interconnected. Prior reviews and meta-analyses, which primarily focused on patients treated prior to 2000, presented conflicting findings concerning the association between hospital or surgeon volume and outcomes in rectal cancer cases. With advancements in rectal cancer resection techniques, such as total mesorectal excision, it is crucial to establish whether surgical volume has an impact on outcomes in patients treated since 2000. Through a systematic literature search and meta-analysis comprising 2845 assessed articles, only 21 satisfied the specified inclusion and exclusion criteria. The study’s conclusion supports the notion that higher hospital volume among patients diagnosed since 2000 has shown a significant protective effect on outcomes for rectal cancer surgery [11].

8. Impact of complications on survival

Postoperative complications are widely recognized to have detrimental effects on both short-term quality of life and the financial burden of care. Additionally, emerging evidence suggests that these complications can also negatively influence long-term oncologic outcomes.

A conducted study by the Dutch cancer group focused on evaluating 11,000 stage-3 colorectal cancer patients within the period of 2008 to 2013. Among these patients, 4899 individuals did not receive adjuvant chemotherapy. In this group, the five-year survival rate was found to be merely 39%. However, when chemotherapy was initiated after the 12th week following surgery, the five-year survival rate witnessed a significant increase to 54%. Moreover, early initiation of chemotherapy, specifically within six weeks after surgery, resulted in a remarkable 5-year survival rate of 76%. These findings highlight the crucial impact of timely administration of adjuvant treatment on patient prognosis. Consequently, mitigating postoperative complications assumes added significance in terms of enhancing patient outcomes [12].

Complications that occur following surgery for colorectal cancer have been associated with a negative effect on survival rates. For instance, a meta-analysis examining the implications of anastomotic leakage revealed a decrease in survival rates along with an increased risk of local recurrence [13]. Similarly, another meta-analysis concentrating on patients with colorectal cancer emphasized the detrimental impact of infective complications on both disease-free survival and overall survival [14].

Postoperative complications may result in the delayed or complete cessation of chemotherapy in patients who have clear indications for systemic treatment.