Cancer cachexia impairs neural respiratory drive in hypoxia but not hypercapnia

Effects of exercise and doxorubicin on acute diaphragm neuromuscular transmission failure

Doxorubicin (DOX) is a highly effective anthracycline antibiotic used to treat a wide variety of cancers including breast cancer, leukemia and lymphoma. Unfortunately, clinical use of DOX is limited due to adverse off-target effects resulting in fatigue, respiratory muscle weakness and dyspnea. The diaphragm is the primary muscle of inspiration and respiratory insufficiency is likely the result of both muscle weakness and neural impairment. However, the contribution of neuropathology to DOX-induced respiratory muscle dysfunction is unclear. We hypothesized that diaphragm weakness following acute DOX exposure is associated with neurotoxicity and that exercise preconditioning is sufficient to improve diaphragm muscle contractility by maintaining neuromuscular integrity. Adult female Sprague-Dawley rats were randomized into four experimental groups: 1) sedentary-saline, 2) sedentary-DOX, 3) exercise-saline or 4) exercise-DOX. Endurance exercise preconditioning consisted of treadmill running for 1 h/day at 30 m/min for 10 days. Twenty-four hours after the last bout of exercise, animals were treated with DOX (20 mg/kg, I.P.) or saline (equal volume). Our results demonstrate that 48-h following DOX administration diaphragm muscle specific force is reduced in sedentary-DOX rats in response to both phrenic nerve and direct diaphragm stimulation. Importantly, endurance exercise preconditioning in DOX-treated rats attenuated the decrease in diaphragm contractile function, reduced neuromuscular transmission failure and altered phrenic nerve morphology. These changes were associated with an exercise-induced reduction in circulating biomarkers of inflammation, nerve injury and reformation. Therefore, the results are consistent with exercise preconditioning as an effective way of reducing respiratory impairment via preservation of phrenic-diaphragm neuromuscular conduction.

An Estimation Formula for Resonance Frequency Using Sex and Height for Healthy Individuals and Patients with Incurable Cancers

Resonance frequency breathing is a technique that involves breathing that maximizes heart rate variability. It is specific to individuals and is determined through a procedure taking approximately 30 min, using a procedure that is often best carried out at specialized medical institutions. This is a physical and time-consuming burden because of hospital visits and measurements, particularly for patients with cancer. Therefore it would be beneficial if a procedure can be found to determine resonance frequency from the patient's physical characteristics, without the need for special assessment procedures. This exploratory cross-sectional study examined the correlation between individual characteristics and resonance frequency in healthy volunteers. Multiple regression analysis was performed with the measured resonance frequency as the target variable and individual characteristic parameters as explanatory variables. The study aims to build an estimation formula for resonance frequency with some of these parameters and assess its validity. In addition, the validity of the formula's applicability to patients with incurable cancers is assessed. A total of 122 healthy volunteers and 32 patients with incurable cancers were recruited as participants. The median resonance frequency of 154 participants was six breaths per min. Sex and height were selected as explanatory variables associated with the measured resonance frequency in the volunteers. The estimation formula for resonance frequency using individual characteristics was 17.90-0.07 × height for men and 15.88-0.06 × height for women. Adjusted R-squared values were 0.55 for men and 0.47 for women. When the measured resonance frequency in patients with incurable cancers was six breaths per minute or less, the resonance frequency estimated by this formula was slightly larger than the measured ones. Information on individual characteristics, such as sex and height, which can be easily obtained, was useful to construct an estimation formula for resonance frequency.

Low Muscle Mass and Radiodensity Associate with Impaired Pulmonary Function and Respiratory Complications in Patients with Esophageal Cancer

BACKGROUND

Sixty percent of patients with esophageal cancer display signs of cachexia at diagnosis. Changes in body composition are common, and muscle mass and quality are measurable through imaging studies. Cachexia leads to functional impairments that complicate treatments, including surgery. We hypothesize that low muscle mass and quality associate with pulmonary function testing parameters, highlighting ventilatory deficits, and postoperative complications in patients receiving esophagectomy.

STUDY DESIGN

We performed a retrospective review of patients receiving esophagectomy between 2012 and 2021 at our facility. PET/CT scans were used to quantify skeletal muscle at the L3 and T4 levels. Patient characteristics were recorded, including pulmonary function testing parameters. Regression models were created to characterize predictive associations.

RESULTS

One hundred eight patients were identified. All were included in the final analysis. In linear regression adjusted for sex, age, and COPD status, low L3 muscle mass independently associated with low forced vital capacity (p < 0.005, β 0.354) and forced expiratory volume in 1 second (p < 0.001, β 0.392). Similarly, T4 muscle mass independently predicted forced vital capacity (p < 0.005, β 0.524) and forced expiratory volume in 1 second (p < 0.01, β 0.480). L3 muscle quality correlated with total lung capacity ( R 0.2463, p < 0.05). Twenty-six patients had pleural effusions postoperatively, associated with low muscle quality on L3 images (p < 0.05). Similarly, patients with hospitalization more than 2 weeks presented with lower muscle quality (p < 0.005).

CONCLUSIONS

Cachexia and low muscle mass are common. Reduced muscle mass and quality independently associate with impaired forced vital capacity, forced expiratory volume in 1 second, and total lung capacity. We propose that respiratory muscle atrophy occurs with weight loss. Body composition analyses may aid in stratifying patients. Pulmonary function testing may also serve as a functional endpoint for clinical trials. These findings highlight the need to study mechanisms that lead to respiratory muscle pathology and dysfunction in tumor-bearing hosts.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

Associations of Overall Survival with Geriatric Nutritional Risk Index in Patients with Advanced Pancreatic Cancer

Nutritional assessment is critical in cancer care to maintain quality of life and improve survival. The Geriatric Nutritional Risk Index (GNRI) may be a practical tool to assess nutritional status and predict survival. This study aimed to examine survival using GNRI in advanced-stage pancreatic cancer (PC). The retrospective analysis used data of patients with stage III or IV PC. Inclusion criteria: age > 18 and hospital admission for at least three days at or following diagnosis between 2014 and 2017. Data collected: demographics, albumin levels, BMI and weight. Days between the first and last admission, median survival and GNRI scores calculated. Patients categorized into groups: any nutritional risk (GNRI ≤ 98) and no nutritional risk (GNRI > 98). 102 patients had a median survival of 87.5 days and mean GNRI of 98.7. Patients surviving longer than 90 days showed higher mean weight (p = 0.0128), albumin (p = 0.0002) and BMI (p = 0.0717) at the first admission. Mean survival days for patients at any nutritional risk were 110 days compared to 310 days for no nutritional risk (p = 0.0002). GNRI score at first admission after diagnosis is associated with survival. It is vital to monitor nutritional status using weight and albumin to promote increased survival from diagnosis.

Feasibility and Efficacy of Inspiratory Muscle Training in Patients with Head and Neck Cancer receiving Concurrent Chemoradiotherapy

OBJECTIVES

Patients with head and neck cancer (HNC) undergoing concurrent chemoradiotherapy (CCRT) often experience pulmonary symptoms. This study evaluated if a 7-week inspiratory muscle training (IMT) program during CCRT is feasible, adherent, and safe in patients with HNC. This study also evaluated the effect of IMT on diaphragm thickness, mobility, and cardiorespiratory parameters in patients with HNC receiving CCRT.

METHODS

Ten participants with advanced stage HNC receiving CCRT were recruited for the study. Feasibility, adherence, and safety of the intervention were the primary outcomes. Changes in diaphragm thickness and mobility, maximal inspiratory pressure, maximal expiratory pressure, forced vital capacity, forced expiratory volume in first second and functional capacity using 6-MWT were measured at baseline and post 7 weeks of CCRT. IMT was performed at one session per day for 5 days a week for 7 weeks. Eight sets of two minutes of inspiratory manoeuvres with one minute rest period between them with intensity of 40% MIP were given.

RESULTS

Ten participants  were included in this study out of the 13 patients screened, indicating the feasibility to be 76.9%. Participants completed a total of 260 training sessions out of the 350 planned sessions denoting the adherence level as 74%. Diaphragm thickness and MEP remained significantly unchanged while significant decline was seen in diaphragm mobility, MIP,FVC, FEV1 and 6-MWD at the end of 7 weeks. No adverse events were reported following the intervention.

CONCLUSION

Inspiratory muscle training did not show significant effect on the diaphragm thickness, mobility, and cardiorespiratory parameters; however, it was feasible, adherent, and safe in patients with HNC receiving CCRT.

Mitochondrial Function and Protein Turnover in the Diaphragm are Altered in LLC Tumor Model of Cancer Cachexia

It is established that cancer cachexia causes limb muscle atrophy and is strongly associated with morbidity and mortality; less is known about how the development of cachexia impacts the diaphragm. The purpose of this study was to investigate cellular signaling mechanisms related to mitochondrial function, reactive oxygen species (ROS) production, and protein synthesis during the development of cancer cachexia. C57BL/J6 mice developed Lewis Lung Carcinoma for either 0 weeks (Control), 1 week, 2 weeks, 3 weeks, or 4 weeks. At designated time points, diaphragms were harvested and analyzed. Mitochondrial respiratory control ratio was ~50% lower in experimental groups, which was significant by 2 weeks of cancer development, with no difference in mitochondrial content markers COXIV or VDAC. Compared to the controls, ROS was 4-fold elevated in 2-week animals but then was not different at later time points. Only one antioxidant protein, GPX3, was altered by cancer development (~70% lower in experimental groups). Protein synthesis, measured by a fractional synthesis rate, appeared to become progressively lower with the cancer duration, but the mean difference was not significant. The development and progression of cancer cachexia induces marked alterations to mitochondrial function and ROS production in the diaphragm and may contribute to increased cachexia-associated morbidity and mortality.

Cancer Cachexia and Related Metabolic Dysfunction

Cancer cachexia is a complex multifactorial syndrome marked by a continuous depletion of skeletal muscle mass associated, in some cases, with a reduction in fat mass. It is irreversible by nutritional support alone and affects up to 74% of patients with cancer-dependent on the underlying type of cancer-and is associated with physical function impairment, reduced response to cancer-related therapy, and higher mortality. Organs, like muscle, adipose tissue, and liver, play an important role in the progression of cancer cachexia by exacerbating the pro- and anti-inflammatory response initially activated by the tumor and the immune system of the host. Moreover, this metabolic dysfunction is produced by alterations in glucose, lipids, and protein metabolism that, when maintained chronically, may lead to the loss of skeletal muscle and adipose tissue. Although a couple of drugs have yielded positive results in increasing lean body mass with limited impact on physical function, a single therapy has not lead to effective treatment of this condition. Therefore, a multimodal intervention, including pharmacological agents, nutritional support, and physical exercise, may be a reasonable approach for future studies to better understand and prevent the wasting of body compartments in patients with cancer cachexia.

Corticospinal Control of Human Locomotion as a New Determinant of Age-Related Sarcopenia: An Exploratory Study

Sarcopenia is a muscle disease listed within the ICD-10 classification. Several operational definitions have been created for sarcopenia screening; however, an international consensus is lacking. The Centers for Disease Control and Prevention have recently recognized that sarcopenia detection requires improved diagnosis and screening measures. Mounting evidence hints towards changes in the corticospinal communication system where corticomuscular coherence (CMC) reflects an effective mechanism of corticospinal interaction. CMC can be assessed during locomotion by means of simultaneously measuring Electroencephalography (EEG) and Electromyography (EMG). The aim of this study was to perform sarcopenia screening in community-dwelling older adults and explore the possibility of using CMC assessed during gait to discriminate between sarcopenic and non-sarcopenic older adults. Receiver Operating Characteristic (ROC) curves showed high sensitivity, precision and accuracy of CMC assessed from EEG Cz sensor and EMG sensors located over Musculus Vastus Medialis [Cz-VM; AUC (95.0%CI): 0.98 (0.92-1.04), sensitivity: 1.00, 1-specificity: 0.89, p < 0.001] and with Musculus Biceps Femoris [Cz-BF; AUC (95.0%CI): 0.86 (0.68-1.03), sensitivity: 1.00, 1-specificity: 0.70, p < 0.001]. These muscles showed significant differences with large magnitude of effect between sarcopenic and non-sarcopenic older adults [Hedge's g (95.0%CI): 2.2 (1.3-3.1), p = 0.005 and Hedge's g (95.0%CI): 1.5 (0.7-2.2), p = 0.010; respectively]. The novelty of this exploratory investigation is the hint toward a novel possible determinant of age-related sarcopenia, derived from corticospinal control of locomotion and shown by the observed large differences in CMC when sarcopenic and non-sarcopenic older adults are compared. This, in turn, might represent in future a potential treatment target to counteract sarcopenia as well as a parameter to monitor the progression of the disease and/or the potential recovery following other treatment interventions.

Cancer cachexia impairs neural respiratory drive in hypoxia but not hypercapnia

BACKGROUND

Cancer cachexia is an insidious process characterized by muscle atrophy with associated motor deficits, including diaphragm weakness and respiratory insufficiency. Although neuropathology contributes to muscle wasting and motor deficits in many clinical disorders, neural involvement in cachexia-linked respiratory insufficiency has not been explored.

METHODS

We first used whole-body plethysmography to assess ventilatory responses to hypoxic and hypercapnic chemoreflex activation in mice inoculated with the C26 colon adenocarcinoma cell line. Mice were exposed to a sequence of inspired gas mixtures consisting of (i) air, (ii) hypoxia (11% O₂ ) with normocapnia, (iii) hypercapnia (7% CO₂ ) with normoxia, and (iv) combined hypercapnia with hypoxia (i.e. maximal chemoreflex response). We also tested the respiratory neural network directly by recording inspiratory burst output from ligated phrenic nerves, thereby bypassing influences from changes in diaphragm muscle strength, respiratory mechanics, or compensation through recruitment of accessory motor pools.

RESULTS

Cachectic mice demonstrated a significant attenuation of the hypoxic tidal volume (0.26mL±0.01mL vs 0.30mL±0.01mL; p<0.05), breathing frequency (317±10bpm vs 344±6bpm; p<0.05) and phrenic nerve (29.5±2.6% vs 78.8±11.8%; p<0.05) responses. On the other hand, the much larger hypercapnic tidal volume (0.46±0.01mL vs 0.46±0.01mL; p>0.05), breathing frequency (392±5bpm vs 408±5bpm; p>0.05) and phrenic nerve (93.1±8.8% vs 111.1±13.2%; p>0.05) responses were not affected. Further, the concurrent hypercapnia/hypoxia tidal volume (0.45±0.01mL vs 0.45±0.01mL; p>0.05), breathing frequency (395±7bpm vs 400±3bpm; p>0.05), and phrenic nerve (106.8±7.1% vs 147.5±38.8%; p>0.05) responses were not different between C26 cachectic and control mice.

CONCLUSIONS

Breathing deficits associated with cancer cachexia are specific to the hypoxic ventilatory response and, thus, reflect disruptions in the hypoxic chemoafferent neural network. Diagnostic techniques that detect decompensation and therapeutic approaches that support the failing hypoxic respiratory response may benefit patients at risk for cancer cachectic-associated respiratory failure.