Low circulating total adiponectin, especially its non-high-molecular weight fraction, represents a promising risk factor for colorectal cancer: a meta-analysis

Multifaceted effects of obesity on cancer immunotherapies: Bridging preclinical models and clinical data

Obesity, defined by excessive body fat, is a highly complex condition affecting numerous physiological processes, such as metabolism, proliferation, and cellular homeostasis. These multifaceted effects impact cells and tissues throughout the host, including immune cells as well as cancer biology. Because of the multifaceted nature of obesity, common parameters used to define it (such as body mass index in humans) can be problematic, and more nuanced methods are needed to characterize the pleiotropic metabolic effects of obesity. Obesity is well-accepted as an overall negative prognostic factor for cancer incidence, progression, and outcome. This is in part due to the meta-inflammatory and immunosuppressive effects of obesity. Immunotherapy is increasingly used in cancer therapy, and there are many different types of immunotherapy approaches. The effects of obesity on immunotherapy have only recently been studied with the demonstration of an "obesity paradox", in which some immune therapies have been demonstrated to result in greater efficacy in obese subjects despite the direct adverse effects of obesity and excess body fat acting on the cancer itself. The multifactorial characteristics that influence the effects of obesity (age, sex, lean muscle mass, underlying metabolic conditions and drugs) further confound interpretation of clinical data and necessitate the use of more relevant preclinical models mirroring these variables in the human scenario. Such models will allow for more nuanced mechanistic assessment of how obesity can impact, both positively and negatively, cancer biology, host metabolism, immune regulation, and how these intersecting processes impact the delivery and outcome of cancer immunotherapy.

The ambiguous role of obesity in oncology by promoting cancer but boosting antitumor immunotherapy

Obesity is nowadays considered a pandemic which prevalence's has been steadily increasingly in western countries. It is a dynamic, complex, and multifactorial disease which propitiates the development of several metabolic and cardiovascular diseases, as well as cancer. Excessive adipose tissue has been causally related to cancer progression and is a preventable risk factor for overall and cancer-specific survival, associated with poor prognosis in cancer patients. The onset of obesity features a state of chronic low-grade inflammation and secretion of a diversity of adipocyte-derived molecules (adipokines, cytokines, hormones), responsible for altering the metabolic, inflammatory, and immune landscape. The crosstalk between adipocytes and tumor cells fuels the tumor microenvironment with pro-inflammatory factors, promoting tissue injury, mutagenesis, invasion, and metastasis. Although classically established as a risk factor for cancer and treatment toxicity, recent evidence suggests mild obesity is related to better outcomes, with obese cancer patients showing better responses to treatment when compared to lean cancer patients. This phenomenon is termed obesity paradox and has been reported in different types and stages of cancer. The mechanisms underlying this paradoxical relationship between obesity and cancer are still not fully described but point to systemic alterations in metabolic fitness and modulation of the tumor microenvironment by obesity-associated molecules. Obesity impacts the response to cancer treatments, such as chemotherapy and immunotherapy, and has been reported as having a positive association with immune checkpoint therapy. In this review, we discuss obesity's association to inflammation and cancer, also highlighting potential physiological and biological mechanisms underlying this association, hoping to clarify the existence and impact of obesity paradox in cancer development and treatment.

Expected and paradoxical effects of obesity on cancer treatment response

Obesity, whose prevalence is pandemic and continuing to increase, is a major preventable and modifiable risk factor for diabetes and cardiovascular diseases, as well as for cancer. Furthermore, epidemiological studies have shown that obesity is a negative independent prognostic factor for several oncological outcomes, including overall and cancer-specific survival, for several site-specific cancers as well as for all cancers combined. Yet, a recently growing body of evidence suggests that sometimes overweight and obesity may associate with better outcomes, and that immunotherapy may show improved response among obese patients compared with patients with a normal weight. The so-called 'obesity paradox' has been reported in several advanced cancer as well as in other diseases, albeit the mechanisms behind this unexpected relationship are still not clear. Aim of this review is to explore the expected as well as the paradoxical relationship between obesity and cancer prognosis, with a particular emphasis on the effects of cancer therapies in obese people.

Association of Adiponectin and Vitamin D With Tumor Infiltrating Lymphocytes and Survival in Stage III Colon Cancer

Background

Adipocyte-derived adiponectin may play a role in the host inflammatory response to cancer. We examined the association of plasma adiponectin with the density of tumor-infiltrating lymphocytes (TILs) in colon cancers and with vitamin D, clinicopathological features, and patient survival.

Methods

Plasma adiponectin and 25-hydroxyvitamin D [25(OH)D] were analyzed by radioimmunoassay in 600 patients with stage III colon cancer who received FOLFOX-based adjuvant chemotherapy (NCCTG N0147 [Alliance]). TIL densities were determined in histopathological sections. Associations with disease-free survival (DFS), time to recurrence, and overall survival were evaluated by multivariable Cox regression adjusting for potential confounders (ie, body mass index, race, TILs, and N stage). All statistical tests were 2-sided.

Results

We found a statistically significant reduction in adiponectin, but not 25(OH)D, levels in tumors with high vs low TIL densities (median = 6845 vs 8984 ng/mL; P = .04). A statistically significant reduction in adiponectin was also observed in obese (body mass index >30 kg/m²) vs nonobese patients (median = 6608 vs 12 351 ng/mL; P < .001), in men vs women (median = 8185 vs 11 567 ng/mL; P < .001), in Blacks vs Whites or Asians (median = 6412 vs 8847 vs 7858 ng/mL; P < .03), and in those with fewer lymph node metastases (N1 vs N2: median = 7768 vs 9253 ng/mL; P = .01). Insufficiency of 25(OH)D (<30 ng/mL) was detected in 291 (48.5%) patients. In multivariable analyses, neither adiponectin nor 25(OH)D were associated with a statistically significant difference in DFS, overall survival , or time to recurrence in models adjusted for potential confounders. We found a statistically significant association of TILs with prognosis, yet no such interaction was observed for the association of adiponectin with TILs for DFS.

Conclusions

Lower circulating adiponectin levels were associated with a statistically significant increase in TIL densities in colon cancers, indicating an enhanced antitumor immune response. In contrast to TILs, neither adiponectin nor 25(OH)D was independently prognostic.

Age-adjusted mortality from pancreatic cancer increased NINE-FOLD in japan from 1950 to 1995 - Was a low-protein quasi-vegan diet a key factor in their former low risk?

During the last half of the twentieth century, age-adjusted mortality from pancreatic cancer in Japan rose about nine-fold in both sexes. Well-characterized risk factors such as smoking, obesity/metabolic syndrome, and heavy alcohol use appear to explain only a modest part of this rise. It is proposed that a diet relatively low in protein, and particularly low in animal protein, was a key determinant of the low risk for pancreatic cancer in mid-century Japan. It is further proposed that pancreatic acinar cells, owing to their extraordinarily high rate of protein synthesis, are at high risk for ER stress; that such stress plays a fundamental role in the induction of most pancreatic cancers; and that low-protein diets help to offset such stress by modulating activities of the kinases GCN2 and mTORC1 while increasing autocrine and systemic production of fibroblast growth factor 21. This model appears to clarify the role of various risk factors and protective factors in pancreatic cancer induction. A vegan or quasi-vegan low-protein diet may have broader potential for decreasing risk for a range of common "Western" cancers.

High levels of leptin and non-high molecular weight-adiponectin in patients with colorectal cancer: Association with chemotherapy and common genetic polymorphisms

Colorectal cancer (CRC) is the third most frequently diagnosed cancer worldwide. Leptin and adiponectin are hormones produced by adipose tissues, which exhibit opposing effects on tumor growth. Leptin promotes tumor development and metastasis, whereas adiponectin attenuates this. The aim of the present study was to assess the possible association between leptin and adiponectin [both high molecular weight (HMW) and non-HMW factions] levels with CRC, CRC response to chemotherapy, and to study the relationship between LEPR (rs6588147), ADIPO (rs266729), LEP (rs2167270), and ADIPO (rs822369) polymorphisms and CRC. A total of 32 blood samples collected from CRC patients were analyzed to identify the serum levels of leptin and adiponectin, and the presence of CRC related polymorphisms. A total of 25 healthy subjects were recruited in the control group. Serum levels of leptin and adiponectin were detected using ELISA whereas DNA from patients and controls was amplified and analyzed using PCR-restriction fragment length polymorphism assay. The results showed that the levels of leptin and non-HMW adiponectin were significantly higher in CRC patients compared with the controls (P<0.05). In addition, HMW adiponectin was significantly higher in patients receiving chemotherapy. The association between LEPR (rs6588147), ADIPO (rs266729), LEP (rs2167270) and ADIPO (rs822369) polymorphisms and CRC was not significant (P>0.05). In conclusion, higher leptin and non-HMW adiponectin levels may be associated with increased CRC. Chemotherapy may positively influence the levels of HMW adiponectin. No association between LEPR (rs6588147), ADIPO (rs266729), LEP (rs2167270) and ADIPO (rs822369) polymorphisms with CRC was found.

Non-genetic biomarkers and colorectal cancer risk: Umbrella review and evidence triangulation

Several associations between non-genetic biomarkers and colorectal cancer (CRC) risk have been detected, but the strength of evidence and the direction of associations are not confirmed. We aimed to evaluate the evidence of these associations and integrate results from different approaches to assess causal inference. We searched Medline and Embase for meta-analyses of observational studies, meta-analyses of randomized clinical trials (RCTs), and Mendelian randomization (MR) studies measuring the associations between non-genetic biomarkers and CRC risk and meta-analyses of RCTs on supplementary micronutrients. We repeated the meta-analyses using random-effects models and categorized the evidence based on predefined criteria. We described each MR study and evaluated their credibility. Seventy-two meta-analyses of observational studies and 18 MR studies on non-genetic biomarkers and six meta-analyses of RCTs on micronutrient intake and CRC risk considering 65, 42, and five unique associations, respectively, were identified. No meta-analyses of RCTs on blood level biomarkers have been found. None of the associations were classified as convincing or highly suggestive, three were classified as suggestive, and 26 were classified as weak. For three biomarkers explored in MR studies, there was evidence of causality and seven were classified as likely noncausal. For the first time, results from both observational and MR studies were integrated by triangulating the evidence for a wide variety of non-genetic biomarkers and CRC risk. At blood level, lower vitamin D, higher homeostatic model assessment-insulin resistance, and human papillomavirus infection were associated with higher CRC risk while increased linoleic acid and oleic acid and decreased arachidonic acid were likely causally associated with lower CRC risk. No association was found convincing in both study types.

A longitudinal study of prediagnostic metabolic biomarkers and the risk of molecular subtypes of colorectal cancer

Body fatness increases the risk of colorectal cancer (CRC). Insulin resistance and altered adipokines are potential mechanisms, but previous biomarker studies have been inconsistent. Intertumoral heterogeneity might provide an explanation. We investigated insulin, C-peptide, adiponectin, and leptin in relation to CRC molecular subtypes using a nested case-control design (1010 cases, 1010 matched controls, median 12.3 years from baseline to CRC diagnosis) from the population-based Northern Sweden Health and Disease Study. Repeated samples were available from 518 participants. Risks of CRC and subtypes, defined by tumor BRAF and KRAS mutations and microsatellite instability (MSI) status, were estimated using conditional logistic regression and linear mixed models. Higher C-peptide and lower adiponectin were associated with increased CRC risk (odds ratios per standard deviation increase (95% CI): 1.11 (1.01, 1.23) and 0.91 (0.83, 1.00), respectively), though weakened when adjusted for body mass index. Insulin and leptin were not associated with CRC risk. Within-individual time trajectories were similar in cases and controls, and no subtype-specific relationships were identified (all P_{heterogeneity} > 0.1). Adiponectin was weakly inversely associated with the risk of KRAS-mutated (P = 0.08) but not BRAF-mutated or KRAS/BRAF-wildtype CRC, consistent with the one previous study. These findings contribute to an increased understanding of the complex role of body size in CRC.

Lower circulating adiponectin is associated with higher risk of renal cell carcinoma: A meta-analysis

BACKGROUND

Changes in circulating adiponectin have been related to the risks of various cancers. However, the association between circulating adiponectin and the risk of renal cell carcinoma has not been fully determined. A meta-analysis was performed to evaluate the relationship between circulating adiponectin and renal cell carcinoma risk.

METHODS

Observational studies that evaluated the association between circulating adiponectin and renal cell carcinoma risk were identified via a systematic search of PubMed and Embase databases. The difference between circulating adiponectin in renal cell carcinoma cases and healthy controls, and the multivariable adjusted association between circulating adiponectin and renal cell carcinoma risk were evaluated. A random effects model was used if significant heterogeneity existed; otherwise a fixed effects model was applied.

RESULTS

Eight case-control studies with 2624 renal cell carcinoma cases and 2904 healthy controls were included. Pooled results showed that circulating adiponectin was significantly lower in renal cell carcinoma cases than in healthy controls (mean difference = -1.08 ug/mL; 95% confidence interval (CI) -1.62, -0.54; P < 0.001). Higher circulating adiponectin was independently associated with a significantly lowered risk of renal cell carcinoma (adjusted odds ratio for 1 SD increment of adiponectin = 0.78; 95% CI: 0.63, 0.96; P = 0.02). Subgroup analyses according to characteristics including study design, ethnics of participants, blood samples, numbers of participants, mean ages of participants, and study quality showed consistent results.

CONCLUSIONS

Lower circulating adiponectin is associated with increased risk of renal cell carcinoma. The potential pathophysiological mechanisms underlying the role of circulating adiponectin in the pathogenesis of renal cell carcinoma deserve further investigation.

Friend or foe: Multiple roles of adipose tissue in cancer formation and progression

Obesity is well-known as the second factor for tumorigenesis after smoking and is bound up with the malignant progression of several kinds of cancers, including esophageal cancer, liver cancer, colorectal cancer, kidney cancer, and ovarian cancer. The increased morbidity and mortality of obesity-related cancer are mostly attributed to dysfunctional adipose tissue. The possible mechanisms connecting dysfunctional adipose tissue to high cancer risk mainly focus on chronic inflammation, obesity-related microenvironment, adipokine secretion disorder, and browning of adipose tissue, and so forth. The stromal vascular cells in adipose tissue trigger chronic inflammation through secreting inflammatory factors and promote cancer cell proliferation. Hypertrophic adipose tissues lead to metabolic disorders of adipocytes, such as abnormal levels of adipokines that mediate cancer progression and metastasis. Cancer patients often show adipose tissue browning and cancerous cachexia in an advanced stage, which lead to unsatisfied chemotherapy effect and poor prognosis. However, increasing evidence has shown that adipose tissue may display quite opposite effects in cancer development. Therefore, the interaction between cancers and adipose tissue exert a vital role in mediates adipose tissue dysfunction and further leads to cancer progression. In conclusion, targeting the dysfunction of adipose tissue provides a promising strategy for cancer prevention and therapy.

Obesity and cancer risk: Emerging biological mechanisms and perspectives

Continuously rising trends in obesity-related malignancies render this disease spectrum a public health priority. Worldwide, the burden of cancer attributable to obesity, expressed as population attributable fraction, is 11.9% in men and 13.1% in women. There is convincing evidence that excess body weight is associated with an increased risk for cancer of at least 13 anatomic sites, including endometrial, esophageal, renal and pancreatic adenocarcinomas; hepatocellular carcinoma; gastric cardia cancer; meningioma; multiple myeloma; colorectal, postmenopausal breast, ovarian, gallbladder and thyroid cancers. We first synopsize current epidemiologic evidence; the obesity paradox in cancer risk and mortality; the role of weight gain and weight loss in the modulation of cancer risk; reliable somatometric indicators for obesity and cancer research; and gender differences in obesity related cancers. We critically summarize emerging biological mechanisms linking obesity to cancer encompassing insulin resistance and abnormalities of the IGF-I system and signaling; sex hormones biosynthesis and pathway; subclinical chronic low-grade inflammation and oxidative stress; alterations in adipokine pathophysiology; factors deriving from ectopic fat deposition; microenvironment and cellular perturbations including vascular perturbations, epithelial-mesenchymal transition, endoplasmic reticulum stress and migrating adipose progenitor cells; disruption of circadian rhythms; dietary nutrients; factors with potential significance such as the altered intestinal microbiome; and mechanic factors in obesity and cancer. Future perspectives regarding prevention, diagnosis and therapeutics are discussed. The aim of this review is to investigate how the interplay of these main potential mechanisms and risk factors, exerts their effects on target tissues provoking them to acquire a cancerous phenotype.