Obesity paradox in cancer: Is bigger really better?

Association of systemic inflammation with the obesity paradox in cancer: results from multi-cohort studies

AIMS

This study aimed to explore whether the obesity paradox exists in overall and specific cancers and to investigate the role of systemic inflammation in the obesity paradox.

METHODS

The Cox proportional hazard model was used to explore the relationship between body mass index (BMI) and all-cause mortality. The mediated effect was used to investigate the proportion of systemic inflammation mediating the relationship between BMI and cancer survival risk.

RESULTS

The survival probability showed a step-like increase with an increase in BMI regardless of pathological stage. Approximately 10.8%-24.0% of the overall association between BMI and all-cause mortality in cancer was mediated by inflammation. In the internal validation, we found evidence of the obesity paradox in all body composition obtained using BIA, with inflammation remaining an important mediating factor. Furthermore, we also validated the existence of the obesity paradox of cancer in NHANES. Systemic inflammation remains an important factor in mediating the association between BMI and prognosis in cancer patients.

CONCLUSIONS

The obesity paradox is prevalent in most cancers, except for hepatic biliary cancer and breast cancer. Inflammation may be one of the true features of the obesity paradox in cancer.

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.

The impact of body mass index on prognosis in patients with colon carcinoma

BACKGROUND

The impact of body mass index (BMI) on prognosis in patients with curatively resected stage I-III colon carcinoma was analyzed.

METHODS

The prospectively collected data of 694 patients who underwent complete mesocolic excision between 2003 and 2014 were analyzed. BMI was classified into four categories: underweight (BMI < 18.5 kg/m²; n = 13), normal weight (BMI 18.5 to 24.9 kg/m²; n = 221), overweight (BMI 25.0 to 29.9 kg/m²; n = 309), and obese (BMI ≥ 30.0 kg/m²; n = 151). Univariate and multivariate analyses for comparison of prognosis were performed.

RESULTS

The 5-year rate of locoregional recurrence in all 694 patients was 2.1%, and no differences were found with respect to BMI (p = 0.759). For distant metastasis, the 5-year rate for all patients was 13.4%, and BMI did not have a significant impact (p = 0.593). The 5-year rate of disease-free survival for all 694 patients was 72.4%. The differences with respect to BMI were not found to be significant in univariate analysis (p = 0.222). In multivariate Cox regression analysis, disease-free survival was significantly better in obese patients (HR 0.7; p = 0.034). Regarding overall survival, the 5-year rate for all patients was 78.1%. In univariate analyses, no significant differences were found for BMI (p = 0.094). In the Cox regression analysis, overweight and obese patients had significantly better survival (overweight: HR 0.7; p = 0.027; obese: HR 0.6; p = 0.019).

CONCLUSION

The better survival of overweight and obese patients in multivariate analyses must be interpreted with caution. It is influenced by several factors and seems to correspond to the phenomenon of the obesity paradox.

Association of Body Mass Index with Survival in Asian Patients with Colorectal Cancer

Purpose

The clinical significance of body mass index (BMI) on long-term outcomes has not been extensively investigated in Asian patients with colorectal cancer (CRC). This study aims to describe the association between BMI and survival, plus providing BMI cutoff value for predicting prognosis in CRC patients.

Materials and Methods

A total of 1,182 patients who had undergone surgery for stage I–III CRC from June 2004 to February 2014 were included. BMI was categorized into four groups based on the recommendation for Asian ethnicity. The optimal BMI cutoff value was determined to maximize overall survival (OS) difference.

Results

In multivariable analysis, underweight BMI was significantly associated with poor OS (hazard ratio [HR], 2.38; 95% confidence interval [CI], 1.55 to 3.71; p < 0.001) and obese BMI was associated with better OS (HR, 0.72; 95% CI, 0.53 to 0.97; p=0.036) compared with the normal BMI. Overweight and obese BMI were associated with better recurrence-free survival (HR, 0.64; 95% CI, 0.42 to 0.99; p=0.046 and HR, 0.58; 95% CI, 0.38 to 0.89; p=0.014, respectively) compared with the normal BMI group. BMI cutoff value was 20.44 kg/m². Adding the BMI cutoff value to cancer staging could increase discriminatory performance in terms of integrated area under the curve and Harrell’s concordance index.

Conclusion

Compared to normal BMI, underweight BMI was associated with poor survival whereas obese BMI was associated with better survival. BMI cutoff value of 20.44 kg/m² is a useful discriminator in Asian patients with CRC.

Association of BMI, comorbidities and all-cause mortality by using a baseline mortality risk model

Objective

The association of body mass index (BMI) and all-cause mortality is controversial, frequently referred to as a paradox. Whether the cause is metabolic factors or statistical biases is still controversial. We assessed the association of BMI and all-cause mortality considering a wide range of comorbidities and baseline mortality risk.

Methods

Retrospective cohort study of Olmsted County residents with at least one BMI measurement between 2000–2005, clinical data in the electronic health record and minimum 8 year follow-up or death within this time. The cohort was categorized based on baseline mortality risk: Low, Medium, Medium-high, High and Very-high. All-cause mortality was assessed for BMI intervals of 5 and 0.5 Kg/m².

Results

Of 39,739 subjects (average age 52.6, range 18–89; 38.1% male) 11.86% died during 8-year follow-up. The 8-year all-cause mortality risk had a “U” shape with a flat nadir in all the risk groups. Extreme BMI showed higher risk (BMI <15 = 36.4%, 15 to <20 = 15.4% and ≥45 = 13.7%), while intermediate BMI categories showed a plateau between 10.6 and 12.5%. The increased risk attributed to baseline risk and comorbidities was more obvious than the risk based on BMI increase within the same risk groups.

Conclusions

There is a complex association between BMI and all-cause mortality when evaluated including comorbidities and baseline mortality risk. In general, comorbidities are better predictors of mortality risk except at extreme BMIs. In patients with no or few comorbidities, BMI seems to better define mortality risk. Aggressive management of comorbidities may provide better survival outcome for patients with body mass between normal and moderate obesity.

Obesity-related Cancers: The Coming Epidemic

The world is in the grip of an obesity pandemic, with tripling of obesity rates since 1975; it is predicted that one-third of people on Earth will be obese by 2025. The health consequences of obesity are primarily thought to be related to cardiometabolic disorders such as diabetes and cardiovascular diseases. It is less well appreciated that obesity has been related to at least 13 different cancers and in future, (with increasing control over tobacco misuse and infections), obesity will be the main cause of cancers. While this is an area of active research, there are large gaps in the definition of what is an obesity related cancer (JRC) and more importantly, what are the underlying mechanisms. To an extent, this is due to the controversy on what constitutes “unhealthy obesity” which is further related to the causes of obesity. This narrative review examines the causes and measurement of obesity, the types of obesity-related cancers and possible mechanisms. The information has wide implications ranging from prevention, screening, prognosis and therapeutic strategies. Obesity related cancers should be an area of high-priority research. Oncologists can contribute by spreading awareness and instituting management measures for individual patients in their care.

Synergizing Mouse and Human Studies to Understand the Heterogeneity of Obesity

Obesity is routinely considered as a single disease state, which drives a "one-size-fits-all" approach to treatment. We recently convened the first annual University of North Carolina Interdisciplinary Nutrition Sciences Symposium to discuss the heterogeneity of obesity and the need for translational science to advance understanding of this heterogeneity. The symposium aimed to advance scientific rigor in translational studies from animal to human models with the goal of identifying underlying mechanisms and treatments. In this review, we discuss fundamental gaps in knowledge of the heterogeneity of obesity ranging from cellular to population perspectives. We also advocate approaches to overcoming limitations in the field. Examples include the use of contemporary mouse genetic reference population models such as the Collaborative Cross and Diversity Outbred mice that effectively model human genetic diversity and the use of translational models that integrate -omics and computational approaches from pre-clinical to clinical models of obesity. Finally, we suggest best scientific practices to ensure strong rigor that will allow investigators to delineate the sources of heterogeneity in the population with obesity. Collectively, we propose that it is critical to think of obesity as a heterogeneous disease with complex mechanisms and etiologies, requiring unique prevention and treatment strategies tailored to the individual.

Overweight and obesity in men with prostate cancer do not constitute risk factors for biochemical recurrence

AIM

To investigate if overweight and obesity were associated with a higher degree of biochemical recurrence (BCR) after radical prostatectomy, in Mexican men with prostate cancer (PCa).

METHODS

We included 180 men with PCa, who underwent radical prostatectomy (RP). Body mass index (BMI) was determined and the degree of PCa aggressiveness was established according to the D'Amico classification. Postoperative follow-up of all patients was performed with PSA quantification every/6 weeks after surgery and then at 3-month intervals for 1 year, followed every/6 months for 5 years. Postoperative BCR was defined as two consecutive increases in PSA levels ≥0.4 ng/mL, after RP.

RESULTS

Sixty eight percent of the patients presented overweight or obesity. We found that only intermediate/high risk patients presented an increased risk factor for BCR-free survival (HR = 4.39; 95% CI = 1.74-11.24; p = 0.002). The median follow-up of all men has been 7.9 years and no significant differences in BCR-free survival time has been observed between the BMI groups.

CONCLUSIONS

The overweight and obesity do not represent a risk factor to present BCR after RP for PCa. However, an intermediate/high risk, according to the D'Amico's classification, constitutes a risk factor to present BCR after radical prostatectomy, which is not related to the BMI.

Extracellular Vesicles Derived From Colorectal Cancer Affects CD8 T Cells: An Analysis Based on Body Mass Index

Colorectal cancer (CRC) is one of the most widely diagnosed cancers worldwide. It has been shown that the body-mass index (BMI) of the patients could influence the tumor microenvironment, treatment response, and overall survival rates. Nevertheless, the mechanism on how BMI affects the tumorigenesis process, particularly the tumor microenvironment is still elusive. Herein, we postulate that extracellular vesicles (EVs) from CRC patients and non-CRC volunteers with different BMI could affect immune cells differently, in CD8 T cells particularly. We isolated the EVs from the archived serum of CRC patients with high and low BMI, as well as healthy controls with similar BMI status. The EVs were further characterized via electron microscopy, western blot and dynamic light scattering. Then, functional analysis was performed on CD8 T cells including apoptosis, cell proliferation, gene expression profiling and cytokine release upon co-incubation with the different EVs. Our results suggest that CRC-derived EVs were able to regulate the CD8 T cells. In some assays, low BMI EVs were functionally different than high BMI EVs. This study highlights the possible difference in the regulatory mechanism of cancer patients-derived EVs, especially on CD8 T cells.

Obesity Paradox: Laboratory Findings in Uncomplicated Obesity. Is Bias a Plausible Explanation?

OBJECTIVES

Obesity predisposes to multiple diseases, such as heart disease, diabetes, stroke, arthritis, and malignancy. However, obese patients have better outcomes than normal-weight patients with some of these disorders, including those admitted to critical care units. We compared the results for common laboratory tests in patients with uncomplicated obesity against the findings in normal-weight patients.

METHODS

Patients who had a comprehensive metabolic profile test were identified. Patients with acute and/or chronic debilitating disorders were excluded, and the laboratory parameters were compared among 4 groups based on body mass index.

RESULTS

With the exception of elevated triglycerides and lower high-density lipoprotein in obese and morbidly obese patients, laboratory findings were not meaningfully different from those in normal-weight patients.

CONCLUSIONS

The obesity paradox of better outcomes in obese patients admitted to critical care units could not be explained on the basis of lower additional disease burden necessitating critical care admission due to abnormal laboratory values at the baseline. It is conceivable that unconscious bias against obese patients, with lower disease burden than normal-weight patients, triggers their admission to critical care, thus creating the appearance of better outcomes.