Liver cancer includes primary liver cancer and metastatic liver cancer. One of the most common types of metastatic liver cancer is colorectal liver metastasis (CRLM), which occurs when cancer cells originating from the colorectal rectum migrate through the bloodstream to the liver. The liver plays a critical role in nutrient metabolism, and liver diseases can lead to an imbalance in energy metabolism (1). Protein–energy malnutrition is commonly observed in patients with liver disease (2). Malnutrition is a common and intractable problem in operative hospitalized patients, with studies showing that between 30% and 50% of cancer patients are found to be malnourished or at risk of malnutrition at hospital admission (3). Gu et al. (4) have provided strong evidence that malnutrition was associated with poor postoperative outcomes, such as wound complications and infections, across joint replacement interventions. Moreover, malnutrition leads to adverse clinical outcomes, such as higher morbidity and mortality, longer hospital stays, and increased hospitalization costs (5–7).

Hepatocellular carcinoma (HCC) is the main pathological type of primary liver cancer. In China, most hepatic malignant tumors are attributed to hepatitis B and C viral infections, which contribute significantly to the global burden of cirrhosis and subsequent HCC (8). Most patients with HCC have a liver cirrhosis background, which affects liver function, particularly the production of serum albumin (9). Generally, liver cirrhotic patients suffer from protein–energy malnutrition (10). Nutritional status and dietary patterns are factors related to the risk of HCC, which also have a critical role in the prognosis of patients with HCC (11). Malnutrition is proposed to determine the postoperative outcome of surgery (12), which is a prognostic factor in patients with HCC and has been shown to negatively affect survival in these patients (13). Prognostic nutritional index and BMI are established immune-nutritional indices associated with postoperative outcomes in HCC (14). The albumin–bilirubin score may serve as a useful predictor of energy malnutrition in patients with HCC (15, 16). Serum albumin level and body mass index are generally used as indicators of malnutrition, with recent reports showing that both are correlated with postoperative mortality (17). The subjective global assessment (SGA), also known as the global clinical assessment (GCA), was proposed by Detsky in 1987 as a nutritional evaluation tool. It is currently used as a method for both screening and evaluating nutritional status, but it is frequently used as an evaluation tool (18).

Several studies have confirmed the association between preoperative malnutrition and surgical outcomes in colorectal cancer and HCC (19–21). However, the effects of malnutrition on colorectal liver metastasis (CRLM), especially in patients without cirrhosis background (22), have not been evaluated. Prehabilitation before a major operation, including muscle training and nutritional support, has been investigated comprehensively and shown to improve postoperative complications and reduce the length of hospital stay (23). However, for noncirrhotic patients with CRLM who are qualified for hepatectomy, the evidence supporting the efficacy of such adjuvant nutritional therapy for postoperative intervention is still lacking.

Therefore, this study aimed to investigate the correlation between preoperative malnutrition, based on albumin level and BMI, and operative outcomes, short-term prognosis, and complications in CRLM patients who underwent hepatectomy. Meanwhile, we prospect to provide clinical guidance for perioperative nutrition support.

Cancer patients with malnutrition often experience a combination of weight loss and dysmetabolism. Whether due to voluntary or involuntary caloric restriction, malnutrition increases the risk of cachexia. Unfavorably, both conditions contribute to the depletion of fat and protein storage, negatively impacting treatment tolerance, complication rates, and survival (25). There is a high prevalence of malnutrition in cancer patients (26), with 50% who are presenting for the first time being malnourished or at risk of malnutrition (27) and 80% who are malnourished during treatment (28), which seriously affects the efficacy of anticancer treatment and patient outcomes (29, 30), contributing to the huge global disease burden.

Malnutrition is a matter of particular concern in patients with primary liver cancer, which is distinguished from liver metastases due to concomitant underlying cirrhosis. The present research was designed to investigate whether preoperative malnutrition impacted operative outcomes in noncirrhotic patients with CRLM. Here, we demonstrated that preoperative malnutrition was associated with high blood transfusion, major postoperative complications, postoperative drainage of the earlier stage, postoperative hemoglobin, and longer hospital stays than those without malnutrition. Moreover, there was no significant difference in mortality rates within 6 months after surgery. The present study reported for the first time that preoperative malnutrition, based on albumin level and BMI, is associated with postoperative outcomes and short-time prognosis of the patients who underwent hepatectomy for CRLM, although the mechanisms remain largely unknown.

Here, we observed that preoperative malnutrition was closely associated with adverse surgical outcomes. First, the blood transfusion and major complications were significantly higher in the malnutrition group. We speculated that high blood transfusion and hypohemoglobin may result from conditions such as malnutrition, severe hemorrhage, and abnormal coagulation factors. In addition, hypohemoglobin before partial hepatectomy was related to the worse nutriture. Multiple studies revealed a better prognosis after curative treatment of malignant tumors if the nutritional status had been optimized before any intervention (31–34). The elder patients were prone to malnutrition. Although the preoperative platelet and INR levels of patients were within the normal range in the malnutrition group, the platelet was lower, and INR was higher than that of those in the normal groups, which is more likely to affect blood loss and blood transfusion. Secondly, we identified that malnutrition was associated with postoperative drainage of the earlier stage. It is well known that malnutrition easily leads to tissue edema, friability, ascites, and susceptibility to infection. Moreover, malabsorption frequently occurring in CRLM patients also tends to result in hypoalbuminemia, which increases the risk of drainage.

Additionally, previous researches suggest that malnutrition increases the incidence of postoperative complications in patients with surgery (35–37). Boram et al. (5) reported that malnutrition is an independent risk factor for complications of pancreaticoduodenectomy in pancreatic head cancer. Here, we performed a multivariate analysis to determine the risk factors for complications after hepatectomy for CRLM and demonstrate that preoperative malnutrition and operation time are independent risk factors for complications. However, it is still unknown why patients with malnutrition have worse postoperative outcomes. Further study was needed to elucidate the exact mechanism of these adverse effects of malnutrition.

While malnutrition is a modifiable risk factor for surgical complications, special attention should be paid to nutritional support, including proper nutritional assessment and therapy by a multidisciplinary team. Nutritional therapy should center on providing enough energy and protein to manage the increased requirements of cancer and partial hepatectomy and overcome the highly catabolic state. Nutritional assessment is of great importance in patients with CRLM, and the goal is to establish a baseline body composition assessment and continue with frequent follow-ups to monitor the response to nutritional therapy. Multiple studies reported that adequate nutritional intervention may improve clinical outcomes and reduce hospital costs in patients (38, 39). For all of this, the study has several limitations. As a retrospective study, selection bias and information bias were inevitable. Therefore, strict and clear criteria were set up for the inclusion and exclusion of research objects, which could better represent the population from which they were derived, to avoid bias. Moreover, we just chose the albumin level and BMI to assess malnutrition because other information, such as bioelectrical impedance, midarm muscle circumference, and muscle mass was not available. A more comprehensive assessment was needed. In addition, blinded methods were used to collect patient information, and objective indicators were used as research information to reduce bias. In the end, this study was performed in a single center, and we need more centers to perform further prospective studies to elucidate the relationship between malnutrition and adverse operative outcomes.

In conclusion, this study suggests that preoperative nutritional assessment and the appropriate interventions can benefit CRLM patients who suffer from colorectal cancer liver metastasis without a cirrhosis background and who underwent hepatectomy to restore energy deficit, avoid worse surgical outcomes, and improve short-term prognostic outcomes. This approach is consistent with the recommendations from the European Society for Clinical Nutrition and Metabolism (ESPEN) expert group (40).