The results of our study suggest that malnutrition is associated with an increased likelihood of negative outcomes in individuals who have survived cancer. Our conclusions are supported by subgroup and sensitivity analyses, which reinforce the reliability of our findings.
The GNRI has become a widely accepted tool for predicting mortality risk in older patients. Bouillanne et al. introduced the GNRI in 2005 as a method for evaluating the nutritional status of elderly individuals, highlighting its effectiveness in quantifying the risk of mortality[10].In comparison to other screening tools, including the Nutritional Risk Screening 2002 (NRS-2002), Malnutrition Universal Screening Tool (MUST), and Malnutrition-Inflammation Score (MIS), the GNRI is noted for its ease of use and enhanced accuracy[9, 25]. The GNRI, a novel index based on body mass index and serum albumin levels, demonstrates a significant improvement in mortality risk prediction compared to utilizing solely body mass index and serum albumin levels[26].Moreover, the GNRI can serve as a valuable tool in everyday clinical settings and as a means of monitoring patients over an extended period, facilitating the early detection of individuals susceptible to malnutrition[11–13].
Prior research has investigated the correlation between GNRI levels and mortality among various cancer patients. Xie et al. conducted a meta-analysis incorporating data from 9 studies involving 2153 gastrointestinal cancer patients, revealing a significant association between lower GNRI levels and reduced overall survival (HR = 1.94, 95% CI 1.65–2.28, p < 0.001). These findings suggest that GNRI can function as an independent prognostic indicator for complications and long-term outcomes in patients with gastrointestinal cancer[27]. Yiu et al. conducted a systematic review of 10 studies encompassing a total of 2793 head and neck cancer patients. Their findings indicated a significant correlation between lower GNRI levels and decreased overall survival rates (HR = 2.84, 95% CI 2.07–3.91, P < 0.00001). This suggests that GNRI may serve as a valuable prognostic tool in routine clinical practice for predicting unfavorable outcomes in patients with head and neck cancer[28]. Shen et al. conducted a comprehensive literature review on the prognostic significance of GNRI in non-small cell lung cancer patients. Their findings indicate that lower GNRI levels are associated with decreased overall survival (HR = 1.96, 95% CI 1.66–2.30, p < 0.00001) and disease-free survival (HR = 1.74, 95% CI: 1.36–2.23, p < 0.0001). These results suggest the potential for GNRI to serve as a valuable tool for patient stratification and the development of personalized treatment strategies in this population[29]. Xu et al. highlighted the significance of malnutrition as an autonomous prognostic indicator for individuals with gastric cancer, correlating with suboptimal tumor treatment outcomes and heightened complication rates[30]. Our investigation, utilizing data from the National Health and Nutrition Examination Survey encompassing older adults in the United States, specifically examined survivors of various cancer types spanning from 1999 to 2018. By conducting an observational analysis on this extensive cohort, we substantiated the link between diminished GNRI values and elevated mortality rates, thereby enhancing the comprehension of the interplay between GNRI and cancer prognosis.
Yu et al. conducted a longitudinal study spanning six years, which revealed a significant association between severe malnutrition in the elderly and increased all-cause mortality. Utilizing the GNRI as a tool to evaluate nutritional status, the researchers observed that individuals aged 60–69 classified as malnourished had a hazard ratio (HR) for death of 2.86 (95% CI 1.44–5.68) compared to those with adequate nutrition. Similarly, in the 70–79 age group, malnourished individuals had a HR of 2.60 (95% CI 1.39–4.85) for mortality compared to their well-nourished counterparts[31]. Huo et al. conducted a study involving 10,037 elderly hypertensive patients from the NHANES database, which revealed a significant correlation between moderate to severe malnutrition, as assessed by GNRI, and reduced survival rates. Upon treating GNRI as a continuous variable and controlling for pertinent covariates, the researchers observed that lower GNRI levels were linked to elevated risks of all-cause mortality and cardiovascular mortality, with hazard ratios of 0.958 (95% CI 0.949–0.967) and 0.956 (95% CI 0.941–0.972), respectively. When treating GNRI as a categorical variable, individuals with moderate to severe malnutrition exhibited significantly higher risks of all-cause mortality and cardiovascular mortality compared to those with good nutrition (HR = 2.112, 95% CI 1.377–3.240, HR = 2.604, 95% CI 1.603–4.229)[11]. In their study, Shen et al. analyzed 4400 elderly diabetic patients from the NHANES database and, after adjusting for relevant covariates, observed that for every one-unit increase in GNRI, the risk of all-cause mortality decreased by 5% (HR = 0.95, 95% CI 0.942–0.966) and the risk of cardiovascular mortality decreased by 4% (HR = 0.96, 95% CI 0.935–0.989). Upon stratifying GNRI, it was observed that the group exhibiting moderate to severe malnutrition displayed the lowest survival rate[12]. In a study conducted by Chai et al., it was discovered that malnutrition was linked to a heightened long-term all-cause mortality risk in a cohort of 579 elderly individuals diagnosed with chronic obstructive pulmonary disease. Following adjustments for all pertinent covariates, the malnourished cohort exhibited a twofold increase in the risk of all-cause mortality in comparison to the nutritionally healthy group (HR = 2.47, 95% CI 1.36–4.5)[13]. This study is the first to examine the correlation between GNRI and mortality in elderly cancer patients. Our findings align with previous research, underscoring the widespread applicability of GNRI as a prognostic indicator for disease outcomes.
The etiology of heightened mortality rates linked to malnutrition among individuals with cancer is intricate and multifaceted. Primarily, cancer patients may exhibit anorexia and diminished appetite while hospitalized as a result of diverse treatment reactions, resulting in ongoing deterioration of their nutritional well-being[32, 33]. This phenomenon is particularly pronounced in elderly cancer patients, who are more vulnerable to malnutrition and face an elevated likelihood of experiencing negative outcomes due to prolonged illness and compromised immune function during hospitalization[34, 35]. Secondly, within the realm of cancer, systemic inflammation contributes to heightened metabolism and enhanced breakdown of fats and proteins[36]. This inflammatory response not only adversely affects blood vessels, causing endothelial dysfunction and smooth muscle cell proliferation and migration, but also heightens the likelihood of cardiovascular events in individuals with cancers[37, 38]. Prolonged cancer may ultimately lead to cachexia, a state characterized by severe metabolic disruption, negative protein and energy balance, and weight loss exceeding 5%[39]. In cachectic individuals, the inflammatory response is heightened, resulting in increased catabolic processes in multiple tissues, which worsens the adverse effects of cancer treatments and associated complications[40]. The persistent presence of cachexia and inflammation may also play a role in diminishing survival rates among cancer patients[41, 42]. Additionally, research on immune cells and cytokines within the tumor microenvironment has demonstrated a clear link between immune metabolism and cancer-induced cachexia. The dysregulated immune metabolism in cancer patients further contributes to the development of cachexia[43]. In conditions of malnutrition, there is a reduction in the quantity and efficacy of T cells in the body, resulting in the deactivation of immune cells and immune suppression[44, 45]. This can exacerbate the primary tumor or give rise to additional complications, ultimately impacting the patient's mortality[46].
Our study is constrained by the inherent limitations of the NHANES database, primarily due to its observational nature which precludes definitive establishment of causal relationships between GNRI levels and mortality rates among cancer survivors. Utilizing data from elderly cancer survivors in the United States, our study aimed to investigate the association between GNRI and mortality rates. However, further prospective studies are warranted to validate our findings in this domain.
Based on the inherent characteristics of the NHANES database, our study has several limitations. Firstly, as an observational study, we are unable to establish a definitive causal relationship between GNRI levels and various mortality rates among cancer survivors. Our research utilized data from elderly cancer survivors in the United States to explore this relationship, necessitating future prospective studies to validate our findings. Secondly, our observational design may be subject to selection bias, which could potentially affect the robustness of our conclusions. Despite controlling for relevant covariates based on previous literature and clinical evidence, the influence of confounding factors cannot be entirely excluded. To mitigate this, we employed a multivariable Cox proportional hazards regression model and conducted subgroup and sensitivity analyses. Thirdly, the NHANES database does not provide specific information regarding cancer characteristics such as type, grade, and stage, limiting our ability to assess the relationship between GNRI levels and mortality rates for different cancer types or stages. Nevertheless, our findings align with previous studies on the relationship between GNRI and mortality rates in individual cancers, suggesting the broader applicability of our results across all cancers. Fourthly, GNRI data in our study was based on a single measurement, and baseline data for patients may change over time, potentially affecting the stability of the observed relationship between GNRI and mortality rates. Finally, our analysis represents a secondary analysis of NHANES data, which generally provides lower evidence strength compared to primary study designs. However, secondary analysis allows for the comprehensive utilization of original data, and our application of weighting techniques enhances the generalizability of our findings.