Revisiting Cancer Cachexia: Pathogenesis, Diagnosis, and Current Treatment Approaches

TLR/NLRP3 inflammasome signaling pathways as a main target in frailty, cachexia and sarcopenia

Mobility disability is a common condition affecting older adults, making walking and the performance of activities of daily living difficult. Frailty, cachexia and sarcopenia are related conditions that occur with advancing age and are characterized by a decline in muscle mass, strength, and functionality that negatively impacts health. Chronic low-grade inflammation is a significant factor in the onset and progression of these conditions. The toll-like receptors (TLRs) and the NLRP3 inflammasome are the pathways of signaling that regulate inflammation. These pathways can potentially be targeted therapeutically for frailty, cachexia and sarcopenia as research has shown that dysregulation of the TLR/NLRP3 inflammasome signaling pathways is linked to these conditions. Activation of TLRs with pathogen-associated molecular patterns (PAMPs or DAMPs) results in chronic inflammation and tissue damage by releasing pro-inflammatory cytokines. Additionally, NLRP3 inflammasome activation enhances the inflammatory response by promoting the production and release of interleukins (ILs), thus exacerbating the underlying inflammatory mechanisms. These pathways are activated in the advancement of disease in frail and sarcopenic individuals. Targeting these pathways may offer therapeutic options to reduce frailty, improve musculoskeletal resilience and prevent or reverse cachexia-associated muscle wasting. Modulating TLR/NLRP3 inflammasome pathways may also hold promise in slowing down the progression of sarcopenia, preserving muscle mass and enhancing overall functional ability in elderly people. The aim of this review is to investigate the signaling pathways of the TLR/NLRP3 inflammasome as a main target in frailty, cachexia and sarcopenia.

Metabolic, Inflammatory, and Molecular Impact of Cancer Cachexia on the Liver

Cancer-associated cachexia (CAC) is a severe wasting syndrome, marked by involuntary weight loss and muscle wasting. It is a leading cause of cancer-related morbidity and mortality, and is driven by systemic, chronic low-grade inflammation. Key cytokines, such as IL-6 and GDF15, activate catabolic pathways in many organs. This study examined the role of inflammation and metabolic disruption in the liver during CAC, focusing on its dual role as both a target and a source of inflammatory factors. The analysis covered protein and lipid metabolism disturbances, including the hepatic production of acute-phase proteins and insulin resistance. Hepatic inflammation contributes to systemic dysfunction in CAC. The increased production of C-Reactive Protein (CRP) impacts muscle wasting, while liver inflammation leads to insulin resistance and hepatic steatosis, aggravating the cachectic state. Therefore, understanding the molecular mechanisms of liver metabolism in CAC is essential for developing effective therapies. Potential interventions include anti-inflammatory treatments, anabolic strategies, and restoration of lipid metabolism. Further research is necessary to explore the liver's full contribution to CAC and its systemic effects, allowing to the development of liver-targeted therapeutic strategies.

Cancer-associated muscle weakness - From triggers to molecular mechanisms

Skeletal muscle weakness is a debilitating consequence of many malignancies. Muscle weakness has a negative impact on both patient wellbeing and outcome in a range of cancer types and can be the result of loss of muscle mass (i.e. muscle atrophy, cachexia) and occur independently of muscle atrophy or cachexia. There are multiple cancer specific triggers that can initiate the progression of muscle weakness, including the malignancy itself and the tumour environment, as well as chemotherapy, radiotherapy and malnutrition. This can induce weakness via different routes: 1) impaired intrinsic capacity (i.e., contractile dysfunction and intramuscular impairments in excitation-contraction coupling or crossbridge cycling), 2) neuromuscular disconnection and/or 3) muscle atrophy. The mechanisms that underlie these pathways are a complex interplay of inflammation, autophagy, disrupted protein synthesis/degradation, and mitochondrial dysfunction. The current lack of therapies to treat cancer-associated muscle weakness highlight the critical need for novel interventions (both pharmacological and non-pharmacological) and mechanistic insight. Moreover, most research in the field has placed emphasis on directly improving muscle mass to improve muscle strength. However, accumulating evidence suggests that loss of muscle function precedes atrophy. This review primarily focuses on cancer-associated muscle weakness, independent of cachexia, and provides a solid background on the underlying mechanisms, methodology, current interventions, gaps in knowledge, and limitations of research in the field. Moreover, we have performed a mini-systematic review of recent research into the mechanisms behind muscle weakness in specific cancer types, along with the main pathways implicated.

Medical cannabis use in oncology and associated outcomes: A scoping review

BACKGROUND

Natural and synthetic cannabinoids are being used worldwide to treat various symptoms in cancer patients. This study aims to map the therapeutic benefits and adverse effects associated with the use of cannabis-based drugs in these outcomes.

METHODS

Following Joanna Briggs Institute guidelines a scoping review was conducted. The study protocol was available in the Open Science Framework public repository. An extensive search strategy involving databases like Cochrane Library, Embase, CINAHL, Medline/PubMed, Lilacs, Google Scholar, and Open Gray for gray literature analysis was executed by a skilled librarian. The inclusion criteria were primary studies (observational and randomized) that evaluated the efficacy and safety of cannabinoids in cancer patients. The review encompassed studies of diverse designs, publication years, and types, as long as they addressed cannabinoids' impact in oncology.

RESULTS

Twenty-nine (82.86%) out of total of 35 were randomized and 6 (14.14%) were non-randomized. About 57.1% of studies utilized registered products as interventions, with THC being the most natural cannabinoid cited in variable doses and administration routes. Moreover, 62.85% of studies specified the cancer types (breast, lung, sarcomas, hematological and reproductive system), while only one study detailed cancer staging. The evaluated outcomes encompassed nausea and vomiting (77.14%), appetite (11.43%), pain (8.57%), and tumor regression (2.86%) across different proportions of studies.

CONCLUSION

Cannabinoids show promise in managing pain, emesis, and anorexia/cachexia linked to cancer progression. New randomized clinical trials with a larger number of participants and observational studies on long-term safety are crucial to affirm their medicinal utility for cancer patients unresponsive to conventional drugs.

Adaptation of nutritional risk screening tools may better predict response to nutritional treatment: a secondary analysis of the randomized controlled trial Effect of early nutritional therapy on Frailty, Functional Outcomes, and Recovery of malnourished medical inpatients Trial (EFFORT)

BACKGROUND

Nutritional screening tools have proven valuable for predicting clinical outcomes but have failed to determine which patients would be most likely to benefit from nourishment interventions. The Nutritional Risk Screening 2002 (NRS) and the Mini Nutritional Assessment (MNA) are 2 of these tools, which are based on both nutritional parameters and parameters reflecting disease severity.

OBJECTIVES

We hypothesized that the adaptation of nutritional risk scores, by removing parameters reflecting disease severity, would improve their predictive value regarding response to a nutritional intervention while providing similar prognostic information regarding mortality at short and long terms.

METHODS

We reanalyzed data of 2028 patients included in the Swiss-wide multicenter, randomized controlled trial EFFORT (Effect of early nutritional therapy on Frailty, Functional Outcomes, and Recovery of malnourished medical inpatients Trial) comparing individualized nutritional support with usual care nutrition in medical inpatients. The primary endpoint was 30-d all-cause mortality.

RESULTS

Although stratifying patients by high compared with low NRS score showed no difference in response to nutritional support, patients with high adapted NRS showed substantial benefit, whereas patients with low adapted NRS showed no survival benefit [adjusted hazard ratio: 0.55 [95% confidence interval (CI): 0.37, 0.80]] compared with 1.17 (95% CI: 0.70, 1.93), a finding that was significant in an interaction analysis [coefficient: 0.48 (95% CI: 0.25, 0.94), P = 0.031]. A similar effect regarding treatment response was found when stratifying patients on the basis of MNA compared with the adapted MNA. Regarding the prognostic performance, both original scores were slightly superior in predicting mortality than the adapted scores.

CONCLUSIONS

Adapting the NRS and MNA by including nutritional parameters only improves their ability to predict response to a nutrition intervention, but slightly reduces their overall prognostic performance. Scores dependent on disease severity may best be considered prognostic scores, whereas nutritional risk scores not including parameters reflecting disease severity may indeed improve a more personalized treatment approach for nourishment interventions. The trial was registered at clinicaltrials.gov as NCT02517476.

Prognostic value of GLIM-defined malnutrition in combination with hand-grip strength or gait speed for the prediction of postoperative outcomes in gastric cancer patients with cachexia

BACKGROUND

Cancer cachexia is associated with impaired functional and nutritional status and worse clinical outcomes. Global Leadership Initiative in Malnutrition (GLIM) consensus recommended the application of GLIM criteria to diagnose malnutrition in patients with cachexia. However, few previous study has applied the GLIM criteria in patients with cancer cachexia.

METHODS

From July 2014 to May 2019, patients who were diagnosed with cancer cachexia and underwent radical gastrectomy for gastric cancer were included in this study. Malnutrition was diagnosed using the GLIM criteria. Skeletal muscle index was measured using abdominal computed tomography (CT) images at the third lumbar vertebra (L3) level. Hand-grip strength and 6-meters gait speed were measured before surgery.

RESULTS

A total of 356 patients with cancer cachexia were included in the present study, in which 269 (75.56%) were identified as having malnutrition based on the GLIM criteria. GLIM-defined malnutrition alone did not show significant association with short-term postoperative outcomes, including complications, costs or length of postoperative hospital stays. The combination of low hand-grip strength or low gait speed with GLIM-defined malnutrition led to a significant predictive value for these outcomes. Moreover, low hand-grip strength plus GLIM-defined malnutrition was independently associated with postoperative complications (OR 1.912, 95% CI 1.151-3.178, P = 0.012). GLIM-defined malnutrition was an independent predictive factor for worse OS (HR 2.310, 95% CI 1.421-3.754, P = 0.001) and DFS (HR 1.815, 95% CI 1.186-2.779, P = 0.006) after surgery. The addition of low hand-grip strength or low gait speed to GLIM-defined malnutrition did not increase its predictive value for survival.

CONCLUSION

GLIM-defined malnutrition predicted worse long-term survival in gastric cancer patients with cachexia. Gait speed and hand-grip strength added prognostic value to GLIM-defined malnutrition for the prediction of short-term postoperative outcomes, which could be incorporated into preoperative assessment protocols in patients with cancer cachexia.

Cancer Cachexia: New Insights and Future Directions

Cancer remains a major health problem and is associated with cachexia in up to 80% of cases, leading to decreased survival and quality of life. Cachexia involves complex metabolic disturbances in both protein and energy balance, muscle wasting phenomena, weight loss, systemic inflammation, overall decreased performance status, and tolerability to treatment. The clinical impact of cancer cachexia is very complex, with early detection of cachectic patients and identification of predictive biomarkers being two key factors for improving survival. Thus, a better understanding of the complexity of cancer cachexia phenomena and its main pathophysiological mechanism is much needed. Our review highlights the most important information about cancer cachexia, aiming to disseminate updated research findings about this highly deadly condition.

The role of the nurse in meeting the educational needs for self-care in cachectic cancer patients and their family caregivers: A scoping review

Objective

To give an overview of what is known about the nurse contribution to education in self-care by people with cancer cachexia and their family caregivers. Nurse-led patient education can help patients and their family caregivers to manage cancer symptoms, cancer treatments, and treatment side effects.

Methods

This scoping review explored the extent to which nurse-led education has become part of the multimodal management of cancer cachexia. It is based on a systematic search of Medline, Embase, CINAHL, APA PsycINFO, and the Cochrane Library. Search limits were English language, date ranges from January 2015 to March 2023, and adults 18 years and older.

Results

A total of 6370 titles were screened, 127 papers and conference abstracts were selected for full-text examination, and 9 publications were included in the review. The analysis found the nurses within the multidisciplinary cancer cachexia care team, like other healthcare professionals, do not have a shared understanding of cancer cachexia and its management. For nurses to be confident and competent in the provision of nurse-led cachexia education, they themselves need evidence-based education in cachexia care and how to tailor education according to cachexia stage, symptoms, emotional response, and social circumstance.

Conclusions

Nurses with the knowledge and confidence to provide cancer cachexia education for their patients can potentially play an important role in the management of cancer cachexia and mitigation of cachexia-related problems.

Evaluation and management of body composition changes in cancer patients

Wasting in cancer patients has long been recognized as a condition that adversely affects cancer patients' quality of life, treatment tolerance, and oncological outcomes. Historically, this condition was mainly evaluated by changes in body weight. However, this approach is not quite accurate because body weight is the overall change of all body compartments. Conditions such as edema and ascites can mask the severity of muscle and adipose tissue depletion. Changes in body composition assessment in cancer patients have historically been underappreciated because of the limited availability of measurement tools. As more evidence highlighting the importance of body composition has emerged, it is imperative to apply a more precise evaluation of nutritional status and a more targeted approach to provide nutritional support for cancer patients. In this review, we will discuss the modalities for evaluating body composition and how to manage body composition changes in cancer patients.

The Warburg effect drives cachectic states in patients with pancreatobiliary adenocarcinoma

We have studied whether the Warburg effect (uncontrolled glycolysis) in pancreatobiliary adenocarcinoma triggers cachexia in the patient. After 74 pancreatobiliary adenocarcinomas were removed by surgery, their glucose transporter-1 and four glycolytic enzymes were quantified using Western blotting. Based on the resulting data, the adenocarcinomas were equally divided into a group of low glycolysis (LG) and a group of high glycolysis (HG). Energy homeostasis was assessed in these cancer patients and in 74 non-cancer controls, using serum albumin and C-reactive protein and morphometrical analysis of abdominal skeletal muscle and fat on computed tomography scans. Some removed adenocarcinomas were transplanted in nude mice to see their impacts on host energy homeostasis. Separately, nude mice carrying tumor grafts of MiaPaCa-2 pancreatic adenocarcinoma cells were treated with the glycolytic inhibitor 3-bromopyruvate and with emodin that inhibited glycolysis by decreasing hypoxia-inducible factor-1α. Adenocarcinomas in both group LG and group HG impaired energy homeostasis in the cancer patients, compared to the non-cancer reference. The impaired energy homeostasis induced by the adenocarcinomas in group HG was more pronounced than that by the adenocarcinomas in group LG. When original adenocarcinomas were grown in nude mice, their glycolytic abilities determined the levels of hepatic gluconeogenesis, skeletal muscle proteolysis, adipose-tissue lipolysis, and weight loss in the mice. When MiaPaCa-2 cells were grown as tumors in nude mice, 3-bromopyruvate and emodin decreased tumor-induced glycolysis and cachexia, with the best effects being seen when the drugs were administered in combination. In conclusion, the Warburg effect in pancreatobiliary adenocarcinoma triggers cancer cachexia.

Race, Ethnicity, and Socioeconomic Factors as Determinants of Cachexia Incidence and Outcomes in a Retrospective Cohort of Patients With Gastrointestinal Tract Cancer

PURPOSE

Cachexia is a paraneoplastic syndrome of unintentional adipose and muscle tissue wasting with severe impacts to functionality and quality of life. Although health inequities across minority and socioeconomically disadvantaged groups are known, the role of these factors in cachexia progression is poorly characterized. This study aims to evaluate the relationship between these determinants and cachexia incidence and survival in patients with gastrointestinal tract cancer.

METHODS

Through retrospective chart review from a prospective tumor registry, we established a cohort of 882 patients with gastroesophageal or colorectal cancer diagnosed between 2006 and 2013. Patient race, ethnicity, private insurance coverage, and baseline characteristics were evaluated through multivariate, Kaplan-Meier, and Cox regression analyses to determine associations with cachexia incidence and survival outcomes.

RESULTS

When controlling for potentially confounding covariates (age, sex, alcohol and tobacco history, comorbidity score, tumor site, histology, and stage), Black (odds ratio [OR], 2.447; P < .0001) and Hispanic (OR, 3.039; P < .0001) patients are at an approximately 150% and 200%, respectively, greater risk of presenting with cachexia than non-Hispanic White patients. Absence of private insurance coverage was associated with elevated cachexia risk (OR, 1.439; P = .0427) compared to privately insured patients. Cox regression analyses with previously described covariates and treatment factors found Black race (hazard ratio [HR], 1.304; P = .0354) to predict survival detriments, while cachexia status did not reach significance (P = .6996).

CONCLUSION

Our findings suggest that race, ethnicity, and insurance play significant roles in cachexia progression and related outcomes that are not accounted for by conventional predictors of health. Disproportionate financial burdens, chronic stress, and limitations of transportation and health literacy represent targetable factors for mitigating these health inequities.

Molecular Insights of MAP4K4 Signaling in Inflammatory and Malignant Diseases

Mitogen-activated protein kinase (MAPK) cascades are crucial in extracellular signal transduction to cellular responses. The classical three-tiered MAPK cascades include signaling through MAP kinase kinase kinase (MAP3K) that activates a MAP kinase kinase (MAP2K), which in turn induces MAPK activation and downstream cellular responses. The upstream activators of MAP3K are often small guanosine-5'-triphosphate (GTP)-binding proteins, but in some pathways, MAP3K can be activated by another kinase, which is known as a MAP kinase kinase kinase kinase (MAP4K). MAP4K4 is one of the widely studied MAP4K members, known to play a significant role in inflammatory, cardiovascular, and malignant diseases. The MAP4K4 signal transduction plays an essential role in cell proliferation, transformation, invasiveness, adhesiveness, inflammation, stress responses, and cell migration. Overexpression of MAP4K4 is frequently reported in many cancers, including glioblastoma, colon, prostate, and pancreatic cancers. Besides its mainstay pro-survival role in various malignancies, MAP4K4 has been implicated in cancer-associated cachexia. In the present review, we discuss the functional role of MAP4K4 in malignant/non-malignant diseases and cancer-associated cachexia and its possible use in targeted therapy.

Unveiling the Role of the Proton Gateway, Uncoupling Proteins (UCPs), in Cancer Cachexia

Uncoupling proteins (UCPs) are identified as carriers of proton ions between the mitochondrial inner membrane and the mitochondrial matrix. ATP is mainly generated through oxidative phosphorylation in mitochondria. The proton gradient is generated across the inner mitochondrial membrane and the mitochondrial matrix, which facilitates a smooth transfer of electrons across ETC complexes. Until now, it was thought that the role of UCPs was to break the electron transport chain and thereby inhibit the synthesis of ATP. UCPs allow protons to pass from the inner mitochondrial membrane to the mitochondrial matrix and decrease the proton gradient across the membrane, which results in decreased ATP synthesis and increased production of heat by mitochondria. In recent years, the role of UCPs in other physiological processes has been deciphered. In this review, we first highlighted the different types of UCPs and their precise location across the body. Second, we summarized the role of UCPs in different diseases, mainly metabolic disorders such as obesity and diabetes, cardiovascular complications, cancer, wasting syndrome, neurodegenerative diseases, and kidney complications. Based on our findings, we conclude that UCPs play a major role in maintaining energy homeostasis, mitochondrial functions, ROS production, and apoptosis. Finally, our findings reveal that mitochondrial uncoupling by UCPs may treat many diseases, and extensive clinical studies are required to meet the unmet need of certain diseases.

Metabolic crosstalk between thermogenic adipocyte and cancer cell: Dysfunction and therapeutics

As one of the largest endocrine organs with a wide distribution in organisms, adipose tissue secretes multiple adipokines, cytokines, metabolites, and exosomes to promote tumour development. Elaborating the crosstalk between cancer cells and adipocytes provides a tissue-level perspective of cancer progression, which reflects the heterogeneity and complexity of human tumours. Three main types of adipose tissues, white, brown, and beige adipose tissue, have been described. Thermogenic capacity is a prominent characteristic of brown and beige adipocytes. Most studies so far mainly focus on the contribution of white adipocytes to the tumour microenvironment. However, the role of thermogenic adipose tissue in malignant cancer behaviour has been largely overlooked. Recently, emerging evidence suggests that beige/brown adipocytes play a key role in the development and progression of various cancers. This review focuses on the bidirectional communication between tumour cells and thermogenic adipocytes and the therapeutic strategies to disrupt this interaction.

Phytochemicals: A potential therapeutic intervention for the prevention and treatment of cachexia

Cachexia, a multifactorial and often irreversible wasting syndrome, is often associated with the final phase of several chronic disorders. Although cachexia is characterized by skeletal muscle wasting and adipose tissue loss, it is a syndrome affecting different organs, which ultimately results in systemic complications and impaired quality of life. The pathogenesis and underlying molecular mechanisms of cachexia are not fully understood, and currently there are no effective standard treatments or approved drug therapies to completely reverse cachexia. Moreover, adequate nutritional interventions alone cannot significantly improve cachexia. Other approaches to ameliorate cachexia are urgently needed, and thus, the role of medicinal plants has received considerable importance in this respect due to their beneficial health properties. Increasing evidence indicates great potential of medicinal plants and their phytochemicals as an alternative and promising treatment strategy to reduce the symptoms of many diseases including cachexia. This article reviews the current status of cachexia, the molecular mechanisms of primary events driving cachexia, and state-of-the-art knowledge that reports the preventive and therapeutic activities of multiple families of phytochemical compounds and their pharmacological mode of action, which may hold promise as an alternative treatment modality for the management of cachexia. Based on our review of various in vitro and in vivo models of cachexia, we would conclude that phytochemicals may have therapeutic potential to attenuate cachexia, although clinical trials are required to unequivocally confirm this premise.

R-CSS: A clinically applicable score to classify cachexia stages in patients with cancer undergoing intensity-modulated radiation therapy

Objective

Accurate cachexia staging is the key to its management. However, there is currently a lack of tools to distinguish the staging of cachexia in patients with cancer undergoing radiotherapy. The Radiotherapy Cachexia Staging Scale (R-CSS) was developed for the stratification of cachexia in patients undergoing cancer radiotherapy.

Methods

Patients with cancer undergoing radiotherapy were divided into four stages - noncachexia, precachexia, cachexia, and refractory cachexia - by the R-CSS scale, and the clinical outcomes of the four groups were compared.

Results

A total of 270 patients with cancer undergoing radiation therapy were included in the study. All participants were classified into four stages of cachexia: stage 0, I, II, and III. Patients with a higher cachexia stage had a higher prevalence of sarcopenia (P ​= ​0.015). Scores on the 16-item M. D. Anderson Symptom Inventory were higher in patients with higher cachexia stages (P ​< ​0.05), but levels of forgetfulness, numbness, and shortness of breath were not higher in these patients (P ​> ​0.05). Patients with higher cachexia stages exhibited better scores on the QLQ-C30 scale (P ​< ​0.05), except for in the domains of cognitive functioning, diarrhea, and dyspnea (P ​> ​0.05). The incidence of treatment-related events (any grade III or higher grade of [non-]hematologic adverse events, the need for hospitalization, emergency room admission) was higher in patients with higher cachexia stages.

Conclusions

The R-CSS scale is a screening tool that can simultaneously distinguish different stages of cachexia.

Novel Diagnostic and Prognostic Tools for Lung Cancer Cachexia: Based on Nutritional and Inflammatory Status

Background

Cachexia is one of the most common complications affecting lung cancer patients that seriously affects their quality-of-life and survival time. This study aimed to analyze the predictors and prognostic factors of lung cancer cachexia as well as to develop a convenient and accurate clinical prediction tool for oncologists.

Methods

In this multicenter cohort study, 4022 patients with lung cancer were retrospectively analyzed. The patients were randomly categorized into training and verification sets (7:3 ratio). Univariate and multivariate logistic regression analyses were performed to determine the risk factors of cachexia in patients with lung cancer. Cox regression analysis was applied to determine independent prognostic factors in the patients with lung cancer cachexia. Meanwhile, two nomograms were established and evaluated by time-dependent receiver operating characteristic curve, calibration curve, and decision curve analysis (DCA).

Results

Stage, serum albumin, ALI, anemia, and surgery were independent risk factors for cachexia in patients with lung cancer. Patients with lung cancer cachexia have a shorter survival time. Sex, stage, serum albumin, ALI, KPS score, and surgery served as independent prognostic factors for patients with lung cancer cachexia. The area under the curves (AUCs) of diagnostic nomogram in the training and validation sets were 0.702 and 0.688, respectively, the AUCs of prognostic nomogram in the training set for 1-, 3-, and 5-year were 0.70, 0.72, and 0.75, respectively, while in the validation set the AUCs were 0.71, 0.75, and 0.79, respectively. The calibration curves and DCA of the two nomograms were consistent and the clinical benefit rate was high.

Conclusion

Cachexia brings an additional economic burden and worsens the prognosis of lung cancer patients. The two nomograms can accurately screen and predict the probability of occurrence of cachexia in lung cancer and the prognosis of patients with lung cancer cachexia, and guide clinical work.

Primary Tumor Fluorine‐18 Fluorodeoxydglucose (18F‐FDG) Is Associated With Cancer-Associated Weight Loss in Non-Small Cell Lung Cancer (NSCLC) and Portends Worse Survival

Aim

To investigate the diagnostic potential of and associations between tumor ¹⁸F‐FDG uptake on PET imaging and cancer-associated weight loss.

Methods

774 non-small cell lung cancer (NSCLC) patients with pre-treatment PET evaluated between 2006 and 2014 were identified. Using the international validated definition of cachexia, the presence of clinically significant pretreatment cancer-associated weight loss (WL) was retrospectively determined. Maximum Standardized Uptake Value (SUV_Max) of ¹⁸F‐FDG was recorded and dichotomized based on 3 experimental cutpoints for survival analyses. Each SUV_Max cutpoint prioritized either survival differences, total cohort comparison sample sizes, or sample size by stage. Patient outcomes and associations between SUV_Max and cancer-associated weight loss were assessed by multivariate, categorical, and survival analyses.

Results

Patients were found to have an increased likelihood of having WL at diagnosis associated with increasing primary tumor SUV_Max after controlling for potentially confounding patient and tumor characteristics on multivariate logistic regression (OR 1.038; 95% CI: 1.012, 1.064; P=0.0037). After stratifying the cohort by WL and dichotomized SUV_Max, both factors were found to be relevant in predicting survival outcomes when the alternative variable was constant. Of note, the most striking survival differences contributed by WL status occurred in high SUV_Max groups, where the presence of WL predicted a median survival time detriment of up to 10 months, significant regardless of cutpoint determination method applied to categorize high SUV_Max patients. SUV_Max classification was found to be most consistently relevant in both WL and no WL groups.

Conclusions

The significant positive association between significant pretreatment cancer-associated weight loss and primary tumor SUV_Max underscores increased glucose uptake as a component of catabolic tumor phenotypes. This substantiates ¹⁸F‐FDG PET analysis as a prospective tool for assessment of cancer-associated weight loss and corresponding survival outcomes. Furthermore, the survival differences observed between WL groups across multiple SUV_Max classifications supports the importance of weight loss monitoring in oncologic workups. Weight loss in the setting of NSCLCs with higher metabolic activity as determined by ¹⁸F‐FDG PET signal should encourage more aggressive and earlier palliative care interventions.

Tumor cell anabolism and host tissue catabolism-energetic inefficiency during cancer cachexia

Cancer-associated cachexia (CC) is a pathological condition characterized by sarcopenia, adipose tissue depletion, and progressive weight loss. CC is driven by multiple factors such as anorexia, excessive catabolism, elevated energy expenditure by growing tumor mass, and inflammatory mediators released by cancer cells and surrounding tissues. In addition, endocrine system, systemic metabolism, and central nervous system (CNS) perturbations in combination with cachexia mediators elicit exponential elevation in catabolism and reduced anabolism in skeletal muscle, adipose tissue, and cardiac muscle. At the molecular level, mechanisms of CC include inflammation, reduced protein synthesis, and lipogenesis, elevated proteolysis and lipolysis along with aggravated toxicity and complications of chemotherapy. Furthermore, CC is remarkably associated with intolerance to anti-neoplastic therapy, poor prognosis, and increased mortality with no established standard therapy. In this context, we discuss the spatio-temporal changes occurring in the various stages of CC and highlight the imbalance of host metabolism. We provide how multiple factors such as proteasomal pathways, inflammatory mediators, lipid and protein catabolism, glucocorticoids, and in-depth mechanisms of interplay between inflammatory molecules and CNS can trigger and amplify the cachectic processes. Finally, we highlight current diagnostic approaches and promising therapeutic interventions for CC.