Cancer is the second leading cause of death in the world and an important barrier to increasing life expectancy in China, placing a heavy burden on economic and public health systems (1). Over the past 35 years, the incidence and mortality rate of liver and stomach cancers have remained high, while that of lung, breast, colorectal, and prostate cancers has been growing rapidly in China (2).

The utilization of bioelectrical impedance analysis (BIA) for measuring body composition has generated significant interest in using various indicators, including skeletal muscle index (SMI), phase angle (PA), fat mass (FM), fat-free mass (FFM), fat-free mass index (FFMI), cellular water, to predict outcomes in patients with lung cancer (3, 4), breast cancer (5), prostate cancer (6), gastric cancer (7) and colorectal cancer (8). In contrast to traditional BIA methods, bioelectrical impedance vector analysis BIVA can provide more objective information about hy and BCM (9). Such equipment is faster, more portable, and provides more information for diagnosing malnutrition compared to cross-sectional imaging and has been proven good agreement with body composition data provided by the computed tomography (CT) (10) and dual-energy X-ray absorptiometry (DXA) (11) methods. Malnutrition is associated with disease progression and cancer treatments, with negative impacts on quality of life, high grade state of inflammation (12), poor tolerance to antineoplastic treatment and decreased survival, in addition to increasing postoperative complications (13), hospital stay and costs (14). Tumor subsite is one of the major risks of malnutrition, with cancers that affect gastrointestinal function having the highest prevalence (75% for gastroesophageal and 70.6% for pancreatic tumors). And the risk of malnutrition in patients with non-gastrointestinal tumors is significantly reduced (26.6–42.9% for lung tumors and 28.6% for prostate/testicle neoplasms), especially since prevalence is lower in patients with breast cancers (15, 16).

It is important to note that cancer treatments, including surgery, may further change body composition, and increase the risk of malnutrition. Patients with operable colorectal cancer showed a significant decrease in current body weight, FM, and visceral fat score and increased the average percentage of SMI and total water content at 3 months after surgery (17). Fredrix et al. were documented that after surgical removal of the tumor 1 year in non-small cell lung carcinoma patients with FM and FFM increased (18). For patients with gastric cancer, FFM and SMI were significantly decreased at 18 to 24 months after operative treatment (19), moreover, lean body mass after gastrectomy had a greater decrease in elderly (≥80 years old) than in non-elderly patients (<80 years old) (20). The above literature describes body composition changes 3-12 months or even more after malignant tumor surgery, and few literatures reported short-term body composition changes during hospitalization. Previous studies had reported that post-operation 1 week loss of lean body mass was significantly greater than the loss of fat mass in gastric cancer patients (21). Moreover, the changes in water distribution, PA, initial reduced muscle function, and altered biochemical values during the first 9 postoperative days were observed in patients after pancreatic surgery (22). However, few studies have reported a comparative analysis of body composition changes during surgical treatment in patients with gastrointestinal cancer and non-gastrointestinal cancer, which provide useful information for cancer prognosis and more precise nutritional support.

In this study, we performed serial evaluations of the body composition changes during surgical treatment using a bioelectrical impedance vector analyzer and compared the changes and contributing factors in body composition between patients with gastrointestinal cancer and non-gastrointestinal cancer.

In the present study, we prospectively analyzed the changes in body composition during the perioperative period with operable patients who were diagnosed with lung, breast, prostate, gastric and colorectal cancers, and divided them into a gastrointestinal cancer group (gastric cancer and colorectal cancer) and non-gastrointestinal cancer group (lung cancer, breast cancer and prostate cancer) to compare differences. The results showed all patients in the study had changes in body composition throughout the hospitalization, the trajectories of FM, FFM, and SMM were significantly different between groups. And the changes in body composition of the gastrointestinal cancer group and non-gastrointestinal cancer group were related to preoperative serum markers of nutrition and age, respectively. To the best of our knowledge, our study is the first to use BIVA to find changes in body composition in patients operated for gastrointestinal and non-gastrointestinal cancer among the Chinese.

Our results indicate that the trajectories of FM, FFM, and SMM were minor increased after surgery and then decreased to below the preoperative level, while the non-gastrointestinal cancer group consistently increased before hospital discharge. This means that the nutritional status of patients with non-gastrointestinal cancer is less affected by surgery, while patients with gastrointestinal cancers have worse nutritional status after surgery. Moreover, patients with longer postoperative stays in bed and lack of exercise had more muscle atrophy and lost significant FFM at the time of discharge for gastrointestinal cancer patients. In addition, the short-term decrease in FM may be related to the accelerated rate of protein catabolism and metabolism caused by the stressful trauma of surgery, the postoperative fasting of patients, the slow recovery of digestive tract function, and the relative lack of nutrition supplemented by food intake (28). In contrast, patients with non-gastrointestinal cancer are less affected by postoperative food intake and activity limited.

Skeletal muscle contributes to systemic effects by secreting cytokines and other myokines (including IL-6, IL-8, IL-15, and leukemia inhibitory factors) through local autocrine, paracrine, and endocrine actions (29). Therefore, lower levels of muscle associated with longer length of stay, higher risk of postsurgical complications and mortality (30), as well as lead to local and systemic inflammation (31), which may enhance catabolism, lead to ongoing muscle loss in cancer patients and associations with cancer survival (32, 33). Supplementation with whey protein, branched-chain amino acid, and vitamin D is not only beneficial for maintaining muscle mass (34), in conjunction with age-appropriate exercise, but also boosts FFM and strength that contribute to well-being in patients (35).

Researchers have considered that cellular hydration plays a protective role against weakness, frailty status and functional decline (36). We observed that the hydration status of the gastrointestinal cancer group temporarily increases after surgery, then declines and remains below preoperative levels. The non-gastrointestinal group had increases in TBW, ECW, and hydration, and this state occurred after surgery and persisted for the remainder of the study period. There is evidence that the cellular hydration state is an important factor controlling cellular protein turnover, protein synthesis and protein degradation are affected in opposite directions by cell swelling and shrinking (37). An increase in cellular hydration (swelling) acts as an anabolic proliferative signal, and loss of plasma fluid and small proteins leads to a decreased plasma capillary oncotic pressure, with ongoing interstitial leakage of fluid and electrolytes resulting in localized edema, which is increased as inflammation impedes the reabsorption and return of fluid to the circulation via the lymphatics (38). Our results showed that the higher the preoperative CRP, the less the decrease in FFM, FFMI, and SMM and the more the increase in ECW before discharge, suggesting that the preoperative inflammatory status of patients with gastrointestinal cancer may influence the distribution of hydration after operation. FFM contains virtually all the water and conducting electrolytes in the body, and its hydration is constant (39). Thus, high preoperative CRP levels and a smaller postoperative decrease in FFM may be associated with an increase in postoperative ECW. The shift in water distribution reflects the depletion of BCM (40), which indicates the impairment of organ function in patients with malignant tumors and affects patient prognosis (41). Moreover, we observed an increase in changes in hydration declines with age in the non-gastrointestinal tumor group. Risks of dehydration increase with advancing age (42), mechanistically, dehydration yields stable metabolism remodeling, an elevation of markers of inflammation and coagulation, and renal glomerular injury (43). Improving hydration throughout life may greatly decrease the prevalence of degenerative diseases relate to age.

PA is a sign of cell membrane health and integrity, hydration, and nutritional status. Previous studies have demonstrated that PA is a predictor of mortality or postoperative complications in different clinical settings (27). Although the vector did not shift significantly in either group of subjects, we observed a shorter impedance vector in the gastrointestinal cancer group with respect to the non-gastrointestinal cancer group on preoperative day 1 and postoperative day 1 ( Figure 2 ). The present findings indicate a significant decrease of PA after surgery both in two groups, suggesting decreased cellular integrity and poorer nutritional status in them. Consistent with previous studies (44, 45), the changes of PA with serum Alb and pre-Alb were observed a remarkable positive correction on postoperative day 1 and before discharge in patients with gastrointestinal cancer. In addition, BCM showed similar postoperative changes to PA. It is suggested that postoperative PA and BCM loss decreases with the increase of preoperative serum nutrient parameters in patients with gastrointestinal cancer. Previously, Barrea et al. (46) documented that PA represents a valid predictor of CRP levels in both sexes regardless of body weight, and is possible to predict nutrition-related inflammation. On 1 day before discharge, we also observed a negative association between the changes of PA and CRP in the gastroenteric cancer group. High CRP before surgery may result in a significant decrease in PA. Therefore, preoperative nutritional supplementation should be encouraged in routine practice in patients undergoing operations for gastrointestinal cancer, which is helpful to suppress perioperative inflammation, improve the postoperative nutritional status, and reduce postoperative infection complications (47, 48). Additionally, body composition can inform the formulation of preoperative nutritional therapy for patients. Although no relationship was found between changes in body composition and baseline characteristics of patients with non-gastroenteric cancer in the present study, preoperative nutrition is also important for them (49).

PG-SGA is a tool to effectively assess the nutritional status of oncology patients (25). Compared to preoperative, the patients in this study all had higher PG-SGA scores and showed significant changes in body composition after surgical treatment. It is evident that body composition is an important component of the comprehensive nutritional evaluation of oncology patients, and this result is consistent with other studies (50, 51). Body composition measures can be a more effective predictor of the malnutrition than BMI or body weight and should be considered as part of preoperative risk management and when designing nutritional interventions for undergoing surgery cancer patients. The above findings indicated that the postoperative body composition of patients with malignant tumors is not only related to tumor type, but also significantly correlated with preoperative nutritional status and age.

Although the BIVA method is not considered the “gold standard” for assessing body composition, it has been shown to provide information on hydration and BCM, which allows for the evaluation of patients in whom we are unable to accurately extrapolated body composition due to altered hydration (52). This body composition measurement is useful in guiding the development of nutritional treatment.

This is the first study to use BIVA to identify early postoperative changes of body composition in Chinese patients undergoing surgery for gastrointestinal and non-gastrointestinal cancers, as a way to provide a foundation for personalized nutritional support during hospitalization. Understanding changes in body composition benefits personalized nutritional support and fluid rehydration programs for perioperative patients. For patients undergoing surgery for gastrointestinal, there is a significant loss and a slow recovery in FFM. Hence, it is important to focus on protein supplementation to prevent hypoproteinemia and excessive consumption of FFM during the perioperative period. For patients undergoing surgery for non-gastrointestinal cancer, it is crucial to prioritize correct fluid rehydration during the perioperative period. This study has several limitations. Although we included multiple cancer patients, the sample size for each cancer was small. A larger sample will be needed to collect more accurate data and make more precise conclusions. We only excluded patients who were diagnosed with abdominal fluid and did not define abnormal hydration status by changes in skinfold thickness, heart rate, blood pressure, and hematological and urine parameters, which can be due to the change in TBW. In addition, there was no data on body composition in patients with non-malignant tumors, so we cannot compare the difference in body composition between cancer patients and patients with non-malignant tumors. It would be helpful for subsequent comparisons if data of body composition closer to normal were available.

We observed significant changes in the early postoperative body composition both in patients with gastrointestinal cancer and non-gastrointestinal cancer after radical resection tumor surgery. Postoperative body composition changes in patients with gastrointestinal cancer are related to preoperative Alb, pre-Alb, CRP, and Hb, whereas postoperative body composition changes in patients with non-gastrointestinal cancer are related to age.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving humans were approved by Shaoxing People’s Hospital (Shaoxing Hospital Zhejiang University School of Medicine). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

BC: data collection, formal analysis and writing original draft. LL: data collection, conceptualization, validation, and writing review and editing. CZ: conceptualization, validation, and writing review and editing. LM: supervision and writing review and editing. QS: data collection, writing review and editing. YF: data collection. MW: conceptualization, supervision, methodology and writing review and editing. SC: project administration, conceptualization, methodology, supervision and data visualization. All authors contributed to the article and approved the submitted version.