Colorectal cancer (CRC) was one of the most prevalent malignant tumors globally, with consistently high morbidity and mortality rates (1). Surgical resection remains the primary treatment modality for CRC (2), yet the postoperative recovery trajectory varies significantly among patients due to individual differences. In recent years, the widespread adoption of the Enhanced Recovery After Surgery (ERAS) paradigm has markedly shortened postoperative hospital stays, reduced healthcare costs, potentially improved surgical outcomes, and mitigated complications. This approach has not only shortened the length of stay (LOS) but also enhanced patient satisfaction (3). However, in clinical practice, a subset of patients experiences prolonged postoperative hospitalizations, which not only escalates the consumption of medical resources but may also adversely impact patient prognosis. Moreover, extended hospitalizations exert negative influences on medical costs, healthcare workflows, and, importantly, on the patients themselves, owing to heightened risks of nosocomial infections and deterioration of the hospital environment (4).

Postoperative ICU management is indicated for patients with severe complications or unstable vital signs. The main goals of ICU care include close monitoring of vital parameters, organ function maintenance, and provision of supportive therapies such as respiratory support, circulatory stabilization, and infection control. Colorectal cancer (CRC) patients with comorbidities are at increased risk of postoperative complications, which can result in prolonged hospital stays, higher healthcare costs, delays in adjuvant therapies, and elevated mortality (5). In Canada, 17.7% of postoperative CRC patients are transferred to the ICU, the highest rate among non - cardiac surgeries (6). Evidence shows that postoperative ICU admission reduces mortality in CRC patients (7). The reasons for ICU admission in these patients include surgical risks, patient - specific risks such as cardiovascular, renal, neurological (e.g., delirium) conditions, and the unpredictability of major postoperative complications (8).

The duration of ICU stay following CRC surgery serves as a crucial indicator of both the quality of postoperative recovery and the efficiency of medical resource utilization. Prolonged ICU stays not only reflect the risk and severity of postoperative complications but are also intimately linked to the consumption of medical resources, patients’ quality of life, and escalating healthcare costs. Shortening the ICU LOS is a cornerstone objective of the ERAS philosophy, contributing to the reduction of postoperative complications, lowering infection risks, enhancing the efficiency of medical resource utilization, and alleviating the economic burden on patients and their families. Furthermore, attention to prolonged ICU stays facilitates the identification of high-risk patients, the optimization of postoperative management strategies, and the delivery of more precise, individualized treatment plans. Therefore, a thorough analysis of the risk factors contributing to prolonged ICU stays following CRC surgery holds significant implications for improving patient outcomes, enhancing medical quality, and advancing the implementation of the ERAS concept. While current research predominantly focuses on postoperative hospital stays, studies specifically addressing ICU LOS are scarce. Consequently, the objective of this study is to analyze, within a retrospective cohort of CRC patients admitted to the ICU postoperatively, the risk factors associated with prolonged ICU stays. This endeavor is of paramount importance for optimizing postoperative management and elevating medical quality.

This study identified independent risk factors for prolonged ICU stay following colorectal cancer surgery, including an open surgical approach, perioperative sepsis, prolonged ventilator use time, the occurrence of lower extremity venous thrombosis, and lower average platelet counts within the first 24 hours of ICU admission.

The decision to admit oncology patients to the ICU is typically made based on the cancer diagnosis and the presence of complications. Recent research has shown that tumor staging is not associated with in-hospital mortality during ICU treatment (9). Consistent with this finding, our study found no correlation between prolonged ICU stay and tumor staging. The significantly higher incidence of postoperative complications in the prolonged ICU stay group compared to the normal ICU stay group may be attributed to multiple interacting factors. These include preoperative pathological status, surgical complexity, intraoperative blood loss, ventilator use time, and the patients’ overall health status. Collectively, these factors contribute to an increased risk of postoperative complications.

The higher proportion of preoperative bowel obstruction and perforation in the prolonged ICU stay group may place patients in a compromised physiological state prior to surgery, thereby increasing the difficulty and risk of the procedure, and consequently, the incidence of postoperative complications. The elevated rate of Class IV incisions in the prolonged ICU stay group, which typically indicates greater surgical complexity and trauma, can lead to more challenging postoperative recovery and a higher likelihood of complications. Additionally, the higher proportion of open surgical procedures in the prolonged ICU stay group, which are associated with greater trauma, longer recovery times, and higher complication rates compared to laparoscopic surgery, further contributes to this trend. The increased incidence of intraoperative blood loss ≥50ml in the prolonged ICU stay group may result in postoperative anemia, hypotension, and other conditions that impede recovery and increase the risk of complications. Prolonged ventilator use may also elevate the risk of respiratory complications, such as pulmonary infections.

The significantly higher rates of perioperative sepsis and acute kidney injury (AKI) in the prolonged ICU stay group may be linked to preoperative pathological status, surgical complexity, and intraoperative blood loss. These complications exacerbate the patient’s condition and prolong recovery time. Open surgery, compared to laparoscopic surgery, is associated with greater trauma and postoperative complications, which can lead to prolonged hospital stays (10). Meta-analyses have indicated that patients undergoing open surgery have significantly longer postoperative hospital stays (OR = 3.35) (10) and that open surgery extends postoperative hospital stays by 2–3 days and ICU stays by 1.5-fold compared to laparoscopic surgery (11). Previous studies have also highlighted the advantages of laparoscopic surgery in reducing postoperative complications and shortening hospital stays (12), with less need for postoperative ICU support. Despite these benefits, surgeons may opt for open surgery in cases of anticipated complexity or unexpected intraoperative challenges. Prior research has confirmed that the surgical approach (open vs. laparoscopic) is a risk factor for postoperative ICU admission in colorectal cancer patients (5). Our study further demonstrates that the surgical approach is also a risk factor for prolonged ICU stay in these patients, emphasizing the importance of selecting an appropriate surgical method to reduce ICU stay duration.

Despite advancements in oncological care, tumor-related complications such as bowel obstruction, intestinal perforation, sepsis, and acute kidney injury continue to pose challenges for oncologists and critical care specialists (13). Notably, cancer patients with septic shock do not exhibit increased in-hospital or ICU mortality rates compared to non-cancer patients (14). However, perioperative sepsis remains a significant factor contributing to prolonged ICU stay following colorectal cancer surgery. Postoperative sepsis in colorectal cancer often arises from intra-abdominal infections, anastomotic leaks, or bacterial translocation, leading to multi-organ dysfunction. Sepsis, identified as the strongest independent risk factor for prolonged ICU stay (OR = 4.2), triggers systemic inflammatory response syndrome (SIRS), multi-organ dysfunction, and immunosuppression (15). It exacerbates inflammatory responses and may cause multi-organ failure, thereby extending ICU stays. This aligns with existing literature on the detrimental effects of sepsis on postoperative recovery. Preoperative perforation and obstruction in colorectal cancer patients can precipitate intra-abdominal infections, with sepsis potentially masking the direct effects of perforation in multivariate models. Similarly, Class IV (contaminated) incisions may indirectly influence ICU stay duration by increasing infection risks, although their effects may be overshadowed by the more direct pathophysiological processes of sepsis.

Prolonged postoperative ventilator use is an independent predictor of prolonged ICU stay (OR = 2.8) (5). Extended ventilator use is often associated with impaired pulmonary function or postoperative complications. Prolonged mechanical ventilation increases the risk of ventilator-associated pneumonia and other complications, thereby prolonging ICU stays. Postoperative respiratory insufficiency in colorectal cancer patients may be linked to prolonged anesthesia times, postoperative pain restricting respiratory movements, or pulmonary infections. Optimizing postoperative respiratory management and reducing ventilator use time are critical measures to shorten ICU stays.

Postoperative venous thromboembolism (VTE), a major and potentially fatal complication of colorectal cancer surgery (16), is associated with tumor hypercoagulability, surgical trauma, and postoperative immobilization. Cancer patients admitted to the ICU postoperatively are at higher risk of lower extremity venous thrombosis compared to non-cancer patients, which may exacerbate systemic inflammatory responses and prolong ICU stays (17). Prophylactic anticoagulation therapy and early mobilization are key strategies to reduce the incidence of lower extremity venous thrombosis. Our study identified lower extremity venous thrombosis as a risk factor for prolonged ICU stay in postoperative colorectal cancer patients.

Lower platelet counts within the first 24 hours of ICU admission (<100×10^9/L) are independently associated with prolonged ICU stays (OR = 1.9) (18). Thrombocytopenia may result from sepsis-associated disseminated intravascular coagulation (DIC), bone marrow suppression, or drug toxicity. Lower average platelet counts within the first 24 hours of ICU admission may reflect postoperative coagulation abnormalities or occult bleeding. Thrombocytopenia is closely linked to sepsis, DIC, and multi-organ failure. Additionally, platelets play a role in inflammatory regulation, and abnormal platelet levels may exacerbate systemic inflammatory responses, impairing organ repair. Our study demonstrated a correlation between lower average platelet counts within the first 24 hours of ICU admission and prolonged ICU stays in postoperative colorectal cancer patients.

Severe complications are associated with prolonged ICU stay. Patients with colorectal cancer often face weakness due to the disease itself and treatment side effects (such as surgery, chemotherapy, malnutrition). Prolonged mechanical ventilation and sedative exposure, leading to ICU-acquired weakness and delirium. The hospitalization experience in the ICU may further exacerbate weakness (19). Preoperative nutritional status, laboratory results such as white blood cell count, liver and kidney function, and the duration of gastrointestinal perforation may also affect the length of ICU stay. Immunoparalysis and persistent systemic inflammation after AKI, predisposing to secondary infections. Non-clinical reasons remain a significant contributor to delayed discharge in a proportion of patients with no postoperative complications. Implementation of a nurse-led “DVT-prevention checklist” may reduce DVT incidence. Awakening-and-Breathing Coordination (ABC) protocol may decrease median ventilation time. Enhanced recovery after surgery (ERAS) protocols are multimodal perioperative care pathways. Implementation of the ERAS protocol for colorectal cancer led to a substantial improvement in compliance and a reduction in LOS, without meaningful effects on complications (20).

In summary, laparotomy, perioperative sepsis, prolonged ventilator use time, occurrence of lower extremity venous thrombosis, and lower average platelet counts within the first 24 hours of ICU admission are risk factors for prolonged ICU stay following colorectal cancer surgery. Therefore, in clinical practice, it is essential to identify, prevent, and control these risk factors early in such patients.