The association of body composition and outcomes following autologous hematopoietic stem cell transplantation in patients with non-Hodgkin lymphoma

Recently there has been a growing interest in evaluating body composition as a marker for prognosis in cancer patients. The association of body composition parameters and outcomes has not been deeply investigated in patients with autologous hematopoietic stem cell transplantation (HSCT) recipients with non-Hodgkin lymphoma (NHL). We conducted a retrospective cohort study of 264 NHL patients who received autologous HSCT. PreHSCT abdominal CT scans at the levels of L3 were assessed for body composition measures. We evaluated sarcopenia, myosteatosis, high visceral adipose tissue (VAT) and high visceral adipose tissue density (VATD). Using multivariable Cox proportional regression, we analyzed the association of clinical and transplant-related characteristics with overall survival (OS), relapse-free survival (RFS), and non-relapse mortality (NRM). In a multivariate regression model, patients with higher VATD had worse OS (HR 1.78; 95% confidence intervals CI 1.08–2.95, p = 0.02) and worse NRM (HR 2.31 95% CI 1.08–4.95, p = 0.02) than with lower VATD. Patients with lower levels of VAT also had worse RFS (HR 1.49 95% CI 1.03–2.15, p = 0.03). Sarcopenia and myosteatosis were not associated with outcomes. High pre-transplant VATD was associated with lower OS and higher NRM, and low pre-transplant VAT was associated with worse RFS in patients with NHL undergoing autologous HSCT.


INTRODUCTION
Obesity, defined by body mass index (BMI) greater than 30 Kg/m 2 , was the first measure of body composition to be studied in cancer.BMI has been postulated to play a role in developing multiple cancers by mechanisms such as reduction in apoptosis, increasing proliferation of tissues, increasing genomic instability, and alteration in macrophage functions due to an inflammatory state [1].However, BMI has been criticized as a prognostic marker in cancer because of its inaccuracy in distinguishing patients with different amounts of fat and muscle distribution, as well as its poor ability to account for ethnic differences among patients [2], leading to the development of techniques that show different body composition compartments.
Body composition parameters such as muscle and adiposity are typically assessed using diagnostic imaging techniques such as computed tomography (CT), dual-energy X-ray absorptiometry, magnetic resonance imaging (MRI), or bioelectrical impedance analysis.Because most patients with cancer get CT scans regularly most of body composition literature in patients with cancer relies on axial CT scans [3][4][5][6][7].The majority of the literature uses L3 as a marker for the evaluation of body composition because abdominal CT is commonly performed in patients with cancer, multiple muscles are at that level, and visceral adiposity not covered by liver.However, body composition has been assessed using other imaging levels such as psoas muscle [8], temporalis muscle [9] (using head and neck CT), and thoracic levels [10,11] (using chest CT).A recent systematic review determined that the current evidence was inadequate to provide definitive recommendations for alternate vertebral slice use for body composition evaluation in patients with cancer [12].Using CT scan-derived body composition, it is possible to obtain muscle mass (patients with low muscle mass are sarcopenic), fat infiltration inside the muscle (patients with high fat infiltration in the muscle have myosteatosis), subcutaneous adiposity, visceral adiposity, and the density of the adipose tissues.In the literature Most of the literature in oncology evaluates the impact of sarcopenia and myosteatosis, including a recent study with 78 patients showing that patients with lymphoma who received autologous hematopoietic stem cell transplantation (HSCT) and were sarcopenic had worse progression-free survival (this study did not analyze the impact of adiposity in the population) [13].Recently there has been a growing interest in other measures of adipose tissue [14,15].A recent review showed that patients with hematological malignancies with high visceral adipose tissue had better overall survival [15], contrary to observations in patients with solid tumors [16].Different adiposity types have been assessed by analyzing adipose tissue density in Hounsfield units (HU) to evaluate these mismatches further.Lower adipose tissue density indicates higher lipid content and is associated with weight gain, obesity, and cardiometabolic risks [17] (Fig. 1).In contrast, high lipid density is associated with poorer survival in multiple myeloma [18].
Autologous HSCT is a routine treatment for some patients with high-risk or relapsed/refractory non-Hodgkin lymphoma (NHL) [19].Patient assessment for risks of non-relapse morbidity and mortality for autologous HSCT relies on subjective parameters such as performance status, frailty measures, and tools such as the hematopoietic cell transplantation-comorbidity index (HCT-CI).In addition, pre-transplant assessments of body composition, especially markers for adiposity (VAT and VATD), may help risk stratify patients before undergoing autologous HSCT to discern patient "fitness" and identify patients at higher risk of adverse outcomes [20].However, there are limited studies that have investigated the impact of body composition parameters in patients deemed fit for autologous HSCT.In this study we evaluated the association of pre-autologous HSCT body composition parameters with outcomes in patients with NHL undergoing autologous transplantation.

METHODS
This was a single-center retrospective cohort study of consecutive patients with pathologically confirmed NHL who underwent pretreatment CT scans or positron emission tomography (PET)-CT (within 30 days from the HSCT) and received autologous HSCT at the Cleveland Clinic from January 2010 to January 2021.We excluded patients without radiology imaging performed within 45 days of HSCT at our institution (N = 139) and those where CT images had metal or other components that impaired the ability to measure body composition measures (N = 22) accurately.Overall, our analysis included 264 patients (Inclusion flowchart on Supplementary 1).Patient information was obtained from our Blood and Marrow Transplant Program's database, which prospectively collects data on demographic, disease, transplant, and outcome-related information.CT images were obtained from the Department of Radiology Informatics.The study was approved by the Cleveland Clinic's Institutional Review Board.Informed consent was obtained from patients.

Body composition assessment
Axial CT images from lumbar L3 segments were analyzed using Slice-O-Matic software with Automated Body Composition Analyzer using Computed Tomography image Segmentation (ABACS) extension (Tomovision Quebec, Canada) by one of the authors (GA), with the technique reviewed by another author (PHC, a musculoskeletal radiology subspecialist).The images reported abdominal body composition measures of muscle-skeletal muscle area in cm 2 , which is then divided by height in meters squared to obtain skeletal muscle index (SMI); which is a measure is used to screen for sarcopenia.
Skeletal muscle density (SMD) in Hounsfield units (HU) is the fat that infiltrates the muscle (myosteatosis).In addition, the CT images also report adiposity measures: visceral adipose tissue (VAT) represents the intraabdominal adipose tissue area at the L3 level in cm 2 [21].Furthermore, visceral adipose tissue density (VATD) pertains to the density of visceral adiposity in HU.
We used the run production average to determine the cut points for all body composition measures.Patients were categorized into high VAT (adiposity quantity) (>147 cm 2 ) and low VAT (≤147 cm 2 ), sarcopenia (SMI < 52 cm 2 /m 2 ), and no sarcopenia (SMI > 52 cm 2 /m 2 ).Similarly, we categorized VATD (adiposity quality) as high (≥ −86 HU) and as low (< −86 HU) density and myosteatosis (SMD < 29 HU) vs. no myosteatosis (SMD ≥ 29 HU).The primary objective was to analyze the impact of body composition in overall survival (OS).The secondary objective was to analyze the impact of body composition parameters in non-relapse mortality (NRM) and relapse-free survival (RFS).Also, we wanted to analyze the correlation between body composition parameters.

Statistical analysis
Pearson Spearman's rank coefficient was used to assess the correlation between variables (closer to 1 is higher correlation).Using log-rank statistics, Cox proportional hazards regression estimated RFS, OS, and NRM between subgroups.A backward elimination procedure was used to identify the final multivariable Cox model, starting with factors associated with disease and with transplant from the univariate table.All tests were two-sided with an alpha = 0.05.
Supplementary 2 demonstrates patients' baseline demographics according to their VAT and VATD.Supplementary 3 highlights demographic information on patients who were excluded from the study.Supplementary 4 shows the associations of low VAT with female gender, non-white race, nonobese patients, and high visceral adipose density.In addition, it highlights the association of high VATD with female gender and with low VAT.

DISCUSSION
In our study, adiposity measures (VAT and VATD) were noted to play an important role in the outcomes of patients with hematological malignancies who receive autologous HSCT.First, the amount of visceral adipose tissue (VAT) impacted disease recurrence; patients with higher VAT had better RFS than those with normal adiposity.When looking at the density of the adipose tissues, patients with high visceral adiposity density (VATD) had worse survival (OS) and shorter time to death without relapse/ recurrence (NRM) than those with normal amount of visceral adiposity density.Measures of muscle (sarcopenia [low SMI] and myosteatosis [low SMD]) and obesity (BMI > 30 kg/m 2 ) were not associated with outcomes in the multivariate model.
Our findings support the current literature suggesting that in hematological malignancies, high VAT is protective [15] and that muscle measures such as sarcopenia, sarcopenic obesity and myosteatosis have an unclear impact on overall survival.Some studies suggest that sarcopenia did not impact overall survival [13,22], while another retrospective study showed that patients with sarcopenia had worse survival after allogeneic stem cell transplant [23].The protective role of high VAT was also confirmed in older patients with diffuse large B cell lymphoma treated with R-CHOP (rituximab, cyclophosphamide, Adriamycin, Vincristine, prednisone) or mini-RCHOP chemotherapy [24] and in older patients with acute myelogenous leukemia [25,26].The mechanism proposed relates to differences in the pharmacokinetics of chemotherapy and drug distribution through tissues [27,28].Cancer cachexia and concurrent adipopenia may result in the loss of some protective mechanisms by decreasing the maturation of regulatory T cells, as those cells are selectively dependent on lipid oxidation [29].
Even though the most recent meta-analysis showed that low VAT was predictive of worse outcomes in hematological malignancies, the results were not homogeneous [15].For example, some studies suggested that higher adiposity was associated with worse outcomes in multiple myeloma [30] and DLBCL [31].Because of these differences, researchers started HCT-CI hematopoietic cell transplantation-comorbidity index, G granulocyte stimulating factor.a American Society for Blood and Marrow Transplantation request for information.
evaluating different adipose tissue types by adiposity density [18], similar to the analysis done in muscle deemed myosteatosis [32].
In our study VATD was associated with outcomes that were not associated with the amount of visceral adiposity tissue (VAT) and the correlation between the two variables was moderate, which suggests that VATD may be a better marker for outcomes in patients who will receive autologous HSCT.Differences in visceral adipose tissue density (VATD) pertain mainly to the amount of lipids inside the adipocytes (Fig. 1).Adipose tissue with high lipid content has a low density (in some studies, this is suggestive of white adipose tissue [33]).Those adipocytes store food calories create a layer of thermal insulation, and provide mechanical protection essential for resisting infection and mechanical injury [34].
On the other hand, increased VATD means that the composition of the tissue is relatively low in lipid, and it has high vascularity and high extravascular matrix [35]; in some studies, these are the characteristics of brown adipose tissue [33].In addition, adipose tissue with high and low density participates in immunomodulation with different profiles of the complement system [36].Adiposity with low density increases proinflammatory cytokines that activate and recruit macrophages as well as dendritic cells [37].In contrast, adipose tissue with high density was found to express high levels of programmed death ligand 1, reducing T cell activation [38].All these mechanisms may be the reason for our cohort's high association of VATD and survival.
Our study supports most of the literature available regarding the impact of VATD in oncology [14].Increased VATD has been associated with worse survival in colorectal [39], gastric [40], pancreatic cancer [41], hepatocellular [42], and Multiple myeloma [18].Cancer cells usually use adipose tissue as their fuel to grow [43].Some studies have shown that the changes from high to low adiposity density in patients with cancer are associated with cachexia and wasting [44,45].Altogether our findings suggest that high VATD is a phenotype that may reflect the energy depletion caused by recurrent NHL.Some cancer-associated adipopenia and cachexia treatments have been proposed, including exercise therapy, nutrition interventions, and supplementation with vitamins and medications [46][47][48].Further trials may help clarify the best method to address abnormal body composition in cancer: therapies focusing on cachexia and adipopenia with physical therapy and nutritional therapy [49] can have a powerful impact; however, it may take a long time to achieve results.Currently, there are no approved medications to target sarcopenia and adipopenia, which may change with future technologies [50].In this study we analyzed pre-transplant body composition, which is clinically useful and routinely performed in lymphoma patients undergoing transplantation.However, future studies may assess how changes in body composition post-transplantation (e.g., at day 100) may impact survival in patients receiving autologous HSCT, which has been done in other cancers [51][52][53].
The limitations of our study come from the retrospective nature, which precludes an evaluation of cause and effect.Also, the homogeneous population with mostly white patients younger than 70 years old may impact the external validity of the results.Our study also did not have measures of frailty, as it would be interesting to evaluate the associations of frailty and adiposity.Another study limitation could be the lack of a standardized method for assessing body composition parameters from the CT scans.Variability in image acquisition protocols, slice thickness, and image resolution can influence the measurements of muscle and adipose tissue, potentially affecting the accuracy and consistency of the results.Despite the imaging limitations, we still found strong correlations between visceral adipose composition and outcomes and expect dedicated imaging protocols to strengthen the results.
The practical implications of our findings suggest that body composition may be used in patients who will undergo autologous HSCT to improve screening for the procedure and theoretically lead to a better determination of fitness before receiving the therapy.Overall, in patients with NHL treated with autologous HSCT, higher VAT is associated with more prolonged   relapse-free survival, and higher VATD is associated with worse overall Survival and Non-relapse mortality.Our findings warrant the need for future investigations into the impact of adiposity quantity and quality in NHL autologous HSCT recipients.

Table 1 .
Patients characteristics at transplant.

Table 2 .
Multivariable Cox model for overall survival, relapse-free survival and non-relapse mortality.VATD visceral adipose tissue density, VAT visceral adipose tissue.