Visceral obesity is associated with better recurrence-free survival after curative surgery for Japanese patients with localized clear cell renal cell carcinoma

Prognostic value of preoperative radiographic perinephric fat features in renal cell carcinoma patients undergoing surgery

BACKGROUND

We aimed to assess the prognostic importance of perinephric fat features in images of patients with non-metastatic renal cell carcinoma (RCC) undergoing surgery.

METHODS

We enrolled RCC patients who underwent surgical treatment between 2011 and 2019. Two characteristics, including perinephric fat thickness and perinephric fat stranding, were evaluated using preoperative computed tomography or magnetic resonance images. The association between perinephric fat characteristics and disease progression was examined by Kaplan-Meier survival analysis and Cox regression model.

RESULTS

In a multivariate Cox proportional hazards model adjusting for tumor stage, intratumoral necrosis, and neutrophil-to-lymphocyte ratio, we found that patients in the thin perinephric fat group (<1 cm) had a poorer progression-free survival (PFS) compared to the thick perinephric fat group (≥1 cm) (HR 2.8; 95% CI 1.175-6.674, p = 0.02). Additionally, the fat stranding group had a poorer PFS than the non-stranding group (HR 3.852; 95% CI 1.082-13.704, p = 0.037). The non-stranding with thick perinephric fat group exhibits the highest cumulative PFS while the stranding with thin perinephric fat group has the lowest cumulative PFS. In receiver operating characteristic curve analysis, combing these two perinephric fat characteristics with tumor stage can achieve a better discriminatory power than tumor stage alone.

CONCLUSIONS

Our study indicates that the evaluation of image-based perinephric fat features is a simple, straightforward, reproducible tool for predicting RCC prognosis and may assist in preoperative risk stratification.

Skeletal muscle and visceral adipose radiodensities are pre-surgical, non-invasive markers of aggressive kidney cancer

INTRODUCTION

Most studies on body composition in kidney cancer have been conducted among patients with metastatic disease. Given that aggressive tumours can adversely impact body composition and even non-metastatic tumours can be aggressive, we evaluated associations between pre-surgical body composition features and tumour pathological features in patients with non-metastatic clear cell renal cell cancer (ccRCC).

METHODS

The Resolve Cohort consists of 1239 patients with non-metastatic ccRCC who underwent nephrectomy at Memorial Sloan Kettering Cancer Center between 2000 and 2020. The cross-sectional areas and radiodensities of skeletal muscle, visceral adipose, and subcutaneous adipose tissues were determined from pre-surgical computed tomography (CT) scans at the third lumbar vertebrae using Automatica software. Pearson's correlation coefficients describe inter-relationships among BMI and body composition variables, while odds ratios (OR) and 95% confidence intervals (CI) estimate associations between continuous body composition features (per 1-standard deviation) and advanced stage (Stage III vs. Stages I-II) and high Fuhrman grade (Grades 3-4 vs. 1-2) from multivariable logistic regression models that considered the potential impact of biological sex, contrast enhanced CTs, and early age at onset of ccRCC.

RESULTS

The cohort was predominantly male (69%), white (89%), and had a median age of 58. The proportion of patients presenting with advanced stage and high-grade disease were 31% and 51%, respectively. In models that adjusted for demographics and all body composition variables simultaneously, decreasing skeletal muscle radiodensity (i.e., more fat infiltration) but increasing visceral adipose tissue radiodensity (i.e., more lipid depletion) were associated with advanced tumour features. Per 8.4 HU decrease in skeletal muscle radiodensity, the odds of presenting with advanced stage was 1.61 (95% CI: 1.34-1.93). Per 7.22 HU increase in visceral adipose tissue radiodensity, the odds of presenting with advanced stage was 1.45 (95% CI: 1.22-1.74). Skeletal muscle index (i.e., sarcopenia) was not associated with either tumour feature. Similar associations were observed for Fuhrman grade, a more direct marker of tumour aggressiveness. Associations did not differ by sex, contrast use, or age at onset of ccRCC.

CONCLUSIONS

Lipid infiltrated skeletal muscle, but lipid depleted visceral adipose tissue were independently associated with advanced tumour features in non-metastatic ccRCC. Findings highlight the importance of evaluating the full range of body composition features simultaneously in multivariable models. Interpreting pre-surgical CTs for body composition for patients may be a novel and non-invasive way to identify patients with aggressive renal tumours, which is clinically relevant as renal biopsies are not routinely performed.

Effect of smoking, hypertension and lifestyle factors on kidney cancer - perspectives for prevention and screening programmes

Renal cell carcinoma (RCC) incidence has doubled over the past few decades. However, death rates have remained stable as the number of incidental renal mass diagnoses peaked. RCC has been recognized as a European health care issue, but to date, no screening programmes have been introduced. Well-known modifiable risk factors for RCC are smoking, obesity and hypertension. A direct association between cigarette consumption and increased RCC incidence and RCC-related death has been reported, but the underlying mechanistic pathways for this association are still unclear. Obesity is associated with an increased risk of RCC, but interestingly, improved survival outcomes have been reported in obese patients, a phenomenon known as the obesity paradox. Data on the association between other modifiable risk factors such as diet, dyslipidaemia and physical activity with RCC incidence are conflicting, and potential mechanisms underlying these associations remain to be elucidated.

Association Between Visceral Fat Area and Cancer Prognosis: A Population-Based Multicenter Prospective Study

BACKGROUND

Diverse indicators have been used to represent adipose tissue, while the relationship between body adipose mass and the prognosis of patients with cancer remains controversial.

OBJECTIVE

This study aimed to explore the indicators of optimal body composition that represent body fat mass to predict risk of cancer-related mortality.

METHODS

We conducted a population-based multicenter prospective cohort study of patients with initial cancer between February 2012 and September 2020. Clinical information, body composition indicators, hematologic test results, and follow-up data were collected. Body composition indicators were analyzed using principal component analysis to select the most representative indicators, and the cutoff value was set according to the optimal stratification method. The hazard ratio (HR) for mortality was calculated using Cox proportional hazards regression models.

RESULTS

Among 14,018 patients with complete body composition data, visceral fat area (VFA) is a more optimal indicator for body fat content (principal component index: 0.961) than body mass index (principal component index: 0.850). The cutoff points for VFA in terms of time to mortality were 66 cm2 and 102 cm2 for gastric/esophageal cancer and other cancers, respectively. Among the 2788 patients treated systemically, multivariate analyses demonstrated that a lower VFA was associated with a higher risk of death in patients with cancer of diverse types (HR: 1.33; 95% CI: 1.08, 1.64; P = 0.007), especially gastric cancer (HR: 2.13; 95% CI: 1.3, 3.49; P = 0.003), colorectal cancer HR: 1.81; 95% CI: 1.06, 3.08; P = 0.030) and nonsmall-cell lung cancer (HR: 1.27; 95% CI: 1.01, 1.59; P = 0.040).

CONCLUSION

VFA is an independent prognostic indicator of muscle mass in patients with diverse types of cancer, particularly gastric, colorectal, and nonsmall-cell lung cancers.

TRIAL REGISTRATION NUMBER

ChiCTR1800020329.

Cohort profile - the Renal cell cancer: Lifestyle, prognosis and quality of life (ReLife) study in the Netherlands

PURPOSE

The Renal cell cancer: Lifestyle, prognosis and quality of life (ReLife) study is set up to obtain insight into the association of patient and tumour characteristics, lifestyle habits and circulating biomarkers with body composition features in patients with localised renal cell cancer (RCC). Further, it aims to assess the association of body composition features, lifestyle habits and circulating biomarkers with clinical outcomes, including health-related quality of life.

PARTICIPANTS

The ReLife study is a multicentre prospective cohort study involving 368 patients with newly diagnosed stages I-III RCC recruited from January 2018 to June 2021 from 18 hospitals in the Netherlands. At 3 months, 1 year and 2 years after treatment, participants fill out a general questionnaire and questionnaires about their lifestyle habits (eg, diet, physical activity, smoking and alcohol consumption), medical history and health-related quality of life. At all three time points, patients wear an accelerometer and have blood samples taken. CT scans for body composition analysis are being collected. Permission is asked for collection of tumour samples. Information about disease characteristics, treatment of the primary tumour and clinical outcomes is being collected from medical records by the Netherlands Cancer Registry.

FINDINGS TO DATE

A total of 836 invited patients were eligible and 368 patients were willing to participate and were included (response rate 44%). The mean age of patients was 62.5±9.0 years and 70% was male. The majority had stage I (65%) disease and were treated with radical nephrectomy (57%). Data collection at 3 months and 1 years after treatment have been finalised.

FUTURE PLANS

Data collection at 2 years after treatment is expected to be finalised in June 2023 and longitudinal clinical data will continue to be collected. Results of studies based on this cohort are important to develop personalised evidence-based lifestyle advice for patients with localised RCC to enable them to get more control over their disease course.

Sex Differences in Renal Cell Carcinoma: The Importance of Body Composition

PURPOSE

To examine sex-specific differences in renal cell carcinoma (RCC) in relation to abdominal fat accumulation, psoas muscle density, tumor size, pathology, and survival, and to evaluate possible associations with RCC characteristics and outcome.

METHODS

A total of 470 patients with RCC who underwent nephrectomy between 2006 and 2019 were included in this retrospective study. Specific characteristics of RCC patients were collected, including sex, height, tumor size, grade, and data on patient survival, if available. Abdominal fat measurements and psoas muscle area were determined at the level of L3 (cm²).

RESULTS

Women had a higher subcutaneous (p < 0.001) and men had a higher visceral fat area, relative proportion of visceral fat area (p < 0.001), and psoas muscle index (p < 0.001). Logistic regression analysis showed an association between higher psoas muscle index and lower grade tumors [women: odds ratio (OR) 0.94, 95% confidence interval (CI) 0.89-0.99, p = 0.011; men: OR 0.97 (95% CI, 0.95-0.99, p = 0.012]. Univariate regression analysis demonstrated an association between psoas muscle index and overall survival (women: OR 1.41, 95% CI 1.03-1.93, p = 0.033; men: OR 1.62 (95% CI, 1.33-1.97, p < 0.001). In contrast, there were no associations between abdominal fat measurements and tumor size, grade, or survival. Also, there were no sex-specific differences in tumor size or tumor grades.

CONCLUSIONS

A higher preoperative psoas muscle index was independently associated with overall survival in RCC patients, with a stronger association in men compared with women. In addition, the psoas muscle index showed an inverse association with tumor grade, whereby this association was slightly more pronounced in women than in men.

T-stage-specific abdominal visceral fat, haematological nutrition indicators and inflammation as prognostic factors in patients with clear renal cell carcinoma

Clear cell renal carcinoma (ccRCC) is the most common histological type of renal cancer and has the highest mortality. Several studies have been conducted on the relationship between adipose tissue and ccRCC prognosis, however, the results have been inconsistent to date. The current study aimed at establishing a link between abdominal fat composition and short-term prognosis in patients with ccRCC after T-stage stratification. We retrospectively analysed 250 patients with pathologically confirmed ccRCC (173 low T-stage and 77 high T-stage) in our hospital. The computed tomography (CT) images were evaluated using ImageJ. Then, subcutaneous and visceral fat areas (SFA and VFA), total fat areas (TFA) and the relative VFA (rVFA) were measured and computed. Meanwhile, biochemical indices of blood serum were analysed. The results showed that rVFA in low T-stage cohort who had a history of short-term postoperative complications were significantly lower than those who did not. No such association was observed in the high T-stage cohort. Further investigation revealed that the correlations between biochemical indexes and fat area-related variables varied across T-stage groups. As a result, rVFA is a reliable independent predictor of short-term prognosis in patients with low T-stage ccRCC but not in patients with high T-stage ccRCC.

Visceral Adipose Tissue Assessment Enhances the Prognostic Value of GLIM Criteria in Patients with Gastric Cancer Undergoing Radical Gastrectomy after Neoadjuvant Treatment

BACKGROUND

The Global Leadership Initiative on Malnutrition (GLIM) criteria has been recently published for diagnosing malnutrition in adults. However, the validity of the GLIM criteria has not been well-established in patients with gastric cancer (GC) treated with neoadjuvant treatment (NT) followed by radical gastrectomy. The present study aimed to explore the prognostic value of GLIM-defined malnutrition before NT and after NT in GC patients and to investigate whether additional visceral adipose tissue (VAT) assessment could improve the predictive power of the GLIM criteria for NT-related adverse events (AEs) and long-term survival.

METHODS

GC patients who underwent radical surgery after NT from June 2016 to June 2020 were enrolled in this study. The cross-sectional areas of total skeletal muscle (TSM) and VAT were measured using computed tomography (CT) before NT and after NT. GLIM-defined malnutrition was diagnosed using the two-step approach, including nutritional risk screening and diagnostic assessment. Low VAT was also added to the diagnosis of malnutrition in this study. The predictive value of these malnutrition diagnoses for NT-related AEs, and long-term survival was evaluated in GC patients.

RESULTS

A total of 182 GC patients were included in this study, of which 66 (36.3%) patients before NT and 55 (30.2%) patients after NT were diagnosed with GLIM-defined malnutrition, respectively. In addition to GLIM-defined malnutrition, 54 (29.7%) patients had additional low VAT before NT, and 39 (21.4%) patients had additional low VAT after NT. GLIM-defined malnutrition alone before NT was not associated with NT-related AEs in GC patients. The addition of low VAT to GLIM-defined malnutrition led to a significant predictive value for NT-related AEs. Furthermore, GLIM-defined malnutrition before NT and after NT were both identified as independent risk factors for overall survival (OS) and disease-free survival (DFS). The combination of low VAT and GLIM-defined malnutrition showed a higher hazard ratio for the prediction of OS and DFS both before NT and after NT.

CONCLUSIONS

The addition of VAT assessment using CT improved the predictive value of GLIM-defined malnutrition for NT-related AEs and long-term survival in GC patients treated with NT followed by radical gastrectomy, which further supports the prognostic importance of assessing adipose tissue simultaneously during the routine nutritional assessment in patients with cancer.

A hint for the obesity paradox and the link between obesity, perirenal adipose tissue and Renal Cell Carcinoma progression

Increasing evidence supports a role for local fat depots in cancer outcomes. Despite the robust positive association of obesity with renal cell carcinoma (RCCa) diagnosis, increased adiposity is inversely related to RCCa oncological outcomes. Here, we sought to ascertain whether imagiologically assessed local fat depots associate with RCCa progression and survival and account for this apparent paradox. A retrospective cohort of renal carcinoma patients elective for nephrectomy (n = 137) were included. Beyond baseline clinicopathological characteristics, computed tomography (CT)-scans at the level of renal hilum evaluated areas and densities of different adipose tissue depots (perirenal, subcutaneous, visceral) and skeletal muscle (erector spinae, psoas and quadratus lumborum muscles) were analyzed. Univariate and multivariable Cox proportional hazards models were estimated following empirical analysis using stepwise Cox regression. Age, visceral adipose tissue (VAT) area and body mass index (BMI) predicted tumour-sided perirenal fat area (R² = 0.584), which presented upregulated UCP1 expression by 27-fold (P = 0.026) and smaller adipocyte areas, compared with subcutaneous depot. Multivariate analyses revealed that increased area of perirenal adipose tissue (PRAT) on the contralateral and tumour side associate with improved progression-free survival (HR = 0.3, 95CI = 0.1-0.8, P = 0.019) and overall survival (HR = 0.3, 95CI = 0.1-0.7, P = 0.009). PRAT measurements using CT, might become a possible tool, well correlated with other measures of obesity such as VAT and BMI, that will improve determination of obesity and contribute to assess the risk for disease progression and mortality in renal cancer patients. Present data supports the obesity paradox in RCCa, assumed that larger PRAT areas seem to protect from disease progression and death.

Association of visceral and subcutaneous adiposity with tumor stage and Fuhrman grade in renal cell carcinoma

Higher BMI has been associated with lower tumor stage and grade and improved survival in renal cell cancer (RCC). BMI cannot distinguish between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT). We examined associations of BMI, VAT, SAT, total adipose tissue (TAT) and relative VAT (rVAT) with tumor stage and grade in RCC patients. In a Dutch multicenter population-based historical cohort study 1039 RCC patients diagnosed between 2008 and 2012 were assessed for VAT and SAT using Computed Tomography images at L3. Sex-stratified multinomial logistic regression analyses were performed (linearly per 10-unit increase) between BMI, VAT, SAT, TAT and relative VAT (rVAT) with tumor stage and Fuhrman grade. Higher VAT, TAT and rVAT were associated with a lower risk of stage IV versus stage I in males (OR 0.93; 95%CI 0.91–0.96, OR 0.95; 95%CI 0.93–0.98, OR 0.97; 95%CI 0.96–0.99, respectively). Females showed similar associations, but only higher VAT was statistically significantly associated with reduced risk of stage IV (OR 0.95 95%CI 0.89–1.00). No associations with grade, SAT or BMI were found. In conclusion, higher VAT and TAT was associated with lower risk of stage IV RCC. This might be due to weight loss or cancer cachexia in stage IV patients.

Adiposity and cancer survival: a systematic review and meta-analysis

PURPOSE

The increasing availability of clinical imaging tests (especially CT and MRI) that directly quantify adipose tissue has led to a rapid increase in studies examining the relationship of visceral, subcutaneous, and overall adiposity to cancer survival. To summarize this emerging body of literature, we conducted a systematic review and meta-analysis of imaging-measured as well as anthropometric proxies for adipose tissue distribution and cancer survival across a wide range of cancer types.

METHODS

Using keywords related to adiposity, cancer, and survival, we conducted a systematic search of the literature in PubMed and MEDLINE, Embase, and Web of Science Core Collection databases from database inception to 30 June 2021. We used a random-effect method to calculate pooled hazard ratios (HR) and corresponding 95% confidence intervals (CI) within each cancer type and tested for heterogeneity using Cochran's Q test and the I2 test.

RESULTS

We included 203 records for this review, of which 128 records were utilized for quantitative analysis among 10 cancer types: breast, colorectal, gastroesophageal, head and neck, hepatocellular carcinoma, lung, ovarian, pancreatic, prostate, and renal cancer. We found that imaging-measured visceral, subcutaneous, and total adiposity were not significantly associated with increased risk of overall mortality, death from primary cancer, or cancer progression among patients diagnosed with these 10 cancer types; however, we found significant or high heterogeneity for many cancer types. For example, heterogeneity was similarly high when the pooled HRs (95% CI) for overall mortality associated with visceral adiposity were essentially null as in 1.03 (0.55, 1.92; I2 = 58%) for breast, 0.99 (0.81, 1.21; I2 = 71%) for colorectal, versus when they demonstrated a potential increased risk 1.17 (0.85, 1.60; I2 = 78%) for hepatocellular carcinoma and 1.62 (0.90, 2.95; I2 = 84%) for renal cancer.

CONCLUSION

Greater adiposity at diagnosis (directly measured by imaging) is not associated with worse survival among cancer survivors. However, heterogeneity and other potential limitations were noted across studies, suggesting differences in study design and adiposity measurement approaches, making interpretation of meta-analyses challenging. Future work to standardize imaging measurements and data analyses will strengthen research on the role of adiposity in cancer survival.

Sarcopenia and systemic inflammation are associated with decreased survival after cytoreductive nephrectomy for metastatic renal cell carcinoma

BACKGROUND

This study was aimed at assessing the associations of sarcopenia, muscle density, adiposity, and inflammation with overall survival (OS) after cytoreductive nephrectomy (CN) for metastatic renal cell carcinoma.

METHODS

In all, 158 patients undergoing CN from 2001 to 2014 had digitized preoperative imaging for tissue segmentation via Slice-O-Matic software (version 5.0) at the mid-L3 level. The skeletal muscle index was calculated with the skeletal muscle area (cm² ) normalized for height (m² ), and the skeletal muscle density (SMD) was calculated with average Hounsfield units. Adiposity was measured with the cross-sectional area (cm² ) of visceral, subcutaneous, and intramuscular adiposity compartments and was similarly normalized for height. The average fat density was obtained in Hounsfield units. OS was estimated with the Kaplan-Meier method. Associations between body composition, inflammation metrics, and relevant clinicopathology and OS were assessed with univariable and multivariate Cox analyses.

RESULTS

Seventy-six of the 158 patients (48%) were sarcopenic. Sarcopenia was associated with elevated neutrophil to lymphocyte ratios (NLRs; P = .02), increased age (P = .001), lower body mass indices (P = .009), greater modified Motzer scores (P = .019), and lower SMD (P = .006). The median OS was 15.0 and 29.4 months for sarcopenic and nonsarcopenic patients, respectively (P = .04). Elevated inflammation (NLR or C-reactive protein), in addition to sarcopenia, was independently associated with OS, with an elevated NLR ≥ 3.5 and sarcopenia associated with the poorest OS at 10.2 months. No associations were observed between measurements of muscle density or adiposity and OS.

CONCLUSIONS

Sarcopenia and measures of high systemic inflammation are additively associated with inferior OS after CN and may be of use in preoperative risk stratification.

LAY SUMMARY

Body composition and sarcopenia (a deficiency in skeletal musculature) have been shown to affect outcomes in cancer. We found that sarcopenic patients had poor survival in comparison with nonsarcopenic patients in the setting of metastatic renal cell carcinoma (mRCC). Patients with both elevated inflammation and sarcopenia had the poorest survival. Sarcopenia is an objective measure of nutrition that can assist in therapeutic counseling and decision-making for individualized treatment in mRCC.

The value of sex-specific abdominal visceral fat as measured via CT as a predictor of clear renal cell carcinoma T stage

Although much is known about how adipose tissue affects the development of clear cell renal carcinoma (ccRCC), little information is available for the utility of sex-specific abdominal visceral fat composition as a predictor of clear cell renal carcinoma (ccRCC) T stage. We conducted CT-based sex-specific abdominal fat measurements in ccRCC patients to assess whether VFA distribution could predict the ccRCC T stage. In total, 253 patients (182 males and 71 females) from our hospital with pathologically confirmed ccRCC (178 low T-stage and 75 high T-stage) were retrospectively reviewed for the present study. Computed tomography (CT) scans were assessed using ImageJ to differentiate between the visceral and subcutaneous fat areas (VFA and SFA), after which the relative VFA (rVFA) and total fat area (TFA) were computed. The relationships between these fat area-related variables, patient age, sex, and BMI, and ccRCC T stage were then evaluated through univariate and multivariate logistic regression analysis to clarify the association between general or sex-specific abdominal visceral fat and T stage. Following adjustment for age, males with high T stage ccRCC exhibited an increased rVFA as compared to males with low T stage ccRCC, with the same relationship being observed among females. This association between rVFA and high T stage was confirmed through both univariate and multivariate models. As thus, sex-specific visceral fat composition is a reliable independent predictor that can identify both male and female patients with high T stage ccRCC.

Skeletal muscle radiodensity and visceral adipose tissue index are associated with survival in renal cell cancer - A multicenter population-based cohort study

INTRODUCTION

Body composition has been associated with disease outcome in several cancer types. Results for localized and metastatic renal cell cancer (RCC) are limited and inconsistent. Our aim was to examine the association between body composition and survival in RCC.

METHODS

We conducted a population-based historical cohort study including patients diagnosed with RCC from 2008 to 2012. Diagnostic Computed Tomography images at the third lumbar vertebra (L3) were assessed for skeletal muscle index (SMI), skeletal muscle density (SMD), visceral adipose tissue index (VATI) and subcutaneous adipose tissue index (SATI). Clinical data was retrieved from medical records. Multivariable Cox regressions with restricted cubic splines were used to determine hazard ratios (HRs) and 95% confidence intervals (95%CIs) for 10-unit increases in body composition features with overall survival (OS) and recurrence-free survival (RFS).

RESULTS

We included 719 stage I-III (of whom 254 (35.3%) died and 148 (21.9%) experienced recurrence) and 320 stage IV RCC patients (of whom 298 (93.1%) died). Median follow-up was 6.35 years (interquartile range; 1.41-8.23). For stage I-III, higher SMD was associated with better OS (men: HR 0.86; 95% CI 0.68-1.08; women: HR 0.69; 95% CI 0.50-0.95). Lower compared to median VATI was associated with worse OS for both men (HR 1.38; 95%CI 1.05-1.83 for VATI = 25) and women (HR 1.67; 95%CI 1.01-2.78 for VATI = 20). For stage IV, higher SMD and higher VATI were associated with better OS among men (HR 0.74; 95% CI 0.59-0.94 and HR 0.93; 95% CI 0.88-0.99, respectively). Results for women were similar but non-significant. No statistically significant associations were found for SMI or SATI.

CONCLUSION

Higher SMD and higher VATI were marginally associated with better survival in RCC patients and might be useful for better prognostication. However, the added value to current prognostic scores needs to be investigated.

Perirenal Fat as a New Independent Prognostic Factor in Patients With Surgically Treated Clear Cell Renal Cell Carcinoma

INTRODUCTION

Recently increasing evidence has suggested that obesity is associated with the development and prognosis of renal cell carcinoma. The aim of the study was to investigate the association between different obesity measurements and overall survival in patients with surgically treated clear cell renal cell carcinoma.

PATIENTS AND METHODS

The data of 342 consecutive patients who underwent radical or partial nephrectomy at Peking University People's Hospital from January 2009 to November 2014 were retrospectively reviewed. Median follow-up was 82 months. The association between different obesity measurements and overall survival was evaluated using the Kaplan-Meier method and Cox regression models.

RESULTS

In univariate Cox regression analyses, perirenal fat accumulation was significantly associated with overall survival (HR: 2.271; 95% CI: 1.311-3.935; P = .003), as well as age, sex, clinical manifestation, surgical option, tumor size, and grade. The other obesity measurements, including body mass index, waist circumference, total adipose tissue, visceral adipose tissue, and percentage of visceral adipose tissue, were not assessed as prognostic indicators of overall survival in this study (P > .05). After adjusting for age, sex, clinical manifestation, surgical option, tumor size, T stage, and tumor grade, perirenal fat accumulation was still identified as an independent predictor of overall survival (HR: 2.264; 95% CI: 1.305-3.926; P == .004). The results of Kaplan-Meier model also revealing that patients with higher percentage of perirenal fat showed poorer overall survival (P == .003).

CONCLUSION

Higher percentage of perirenal adipose tissue is independently associated with increased mortality risk in surgically treated clear cell renal cell carcinoma.

Impact of body composition on clinical outcomes in people with gastric cancer undergoing radical gastrectomy after neoadjuvant treatment

OBJECTIVES

The influence of body composition on clinical outcomes in individuals with gastric cancer (GC) undergoing radical gastrectomy after neoadjuvant treatment (NT) remains unclear. The purpose of this retrospective study was to investigate the association between body composition before NT or after NT and clinical outcomes in individuals with GC receiving multimodal treatments.

METHODS

This retrospective study included individuals with GC who received NT followed by radical gastrectomy between January 2016 and December 2018. Skeletal muscle, visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) were measured by cross-sectional areas at the level of third lumbar vertebra based on single-slice computed tomography scan prior to NT and prior to the surgical operation. Sarcopenia, high VAT, and high SAT were defined using cutoff points of skeletal muscle index, visceral fat area, and subcutaneous fat area. Univariate and multivariate analyses were performed to evaluate risk factors of NT-related adverse events, postoperative complications and predictors of long-term survival.

RESULTS

A total of 110 individuals with GC were enrolled in this study. Sarcopenia was present in 62.7% of them before NT and in 56.4% after NT. Sarcopenia before NT was associated with more NT-related adverse events (odds ratio, 2.901; 95% confidence interval [CI], 1.205-6.983; P = 0.018). High VAT after NT (≥106 cm²) was associated with an increasing incidence of postoperative complications (odds ratio, 4.261; 95% CI, 1.332-13.632; P = 0.015). No body-composition parameter was relevant to tumor pathologic response to NT. As for long-term survival, poor overall survival was associated with both low VAT before NT (<120 cm²; hazard ratio [HR], 2.542; 95% CI, 1.111-5.817; P = 0.027) and low SAT after NT (<99.5 cm²; HR, 2.743; 95% CI, 1.248-6.027; P = 0.012). Similarly, shorter disease-free survival was associated with low VAT before NT (<120 cm²; HR, 2.502; 95% CI, 1.222-5.124; P = 0.012) and low VAT after NT (<106 cm²; HR, 2.505; 95% CI, 1.172-5.358; P = 0.018).

CONCLUSIONS

Body composition measured by computed tomography could predict NT-related adverse events, postoperative complications, and long-term survival in multimodal treatments for GC. More meaningfully, adipose-tissue status has significant prognostic value for individuals with advanced GC.

Visceral Adiposity as a Significant Predictor of Sunitinib-Induced Dose-Limiting Toxicities and Survival in Patients with Metastatic Clear Cell Renal Cell Carcinoma

Sunitinib is a first-line treatment for metastatic renal cell carcinoma (mRCC). Little is known about the predictive factors of sunitinib-induced dose-limiting toxicity (DLT) in Asian populations. We investigated whether body composition predicts sunitinib-induced DLT. We retrospectively reviewed sunitinib-treated Korean patients with clear cell mRCC from eight institutions. Body composition was measured using computed tomography. DLT was defined as any adverse event leading to dose reduction or treatment discontinuation. Univariate analysis was used to compare body composition indices, and logistic regression analyses were performed for factors predicting early DLT. Overall, 111/311 (32.5%) of patients experienced DLT. Significant differences were observed in the subcutaneous adipose tissue index (SATI; p = 0.001) and visceral adipose tissue index (VATI; p < 0.001) between patients with and without DLT. Multivariate analyses revealed that VATI (odds ratio: 1.013; p = 0.029) was significantly associated with early DLT. Additionally, 20% of patients who had a body mass index (BMI) greater than 23 kg/m² and a low VATI experienced DLT, whereas 34.3% of the remaining groups had DLT (p = 0.034). Significant differences were observed for median progression-free survival (13.0 vs. 26.0 months, respectively; p = 0.006) between patients with low and high VATI. Visceral adiposity was a significant predictor of sunitinib-associated DLT and survival. Patients with a low VATI and a BMI greater than 23 kg/m² experienced lower DLTs.

The association of body composition parameters and adverse events in women receiving chemotherapy for early breast cancer

BACKGROUND

Body composition metrics as predictors of adverse events are a growing area of interest in oncology research. One barrier to the use of these metrics in clinical practice is the lack of standardized cut points for identifying patients with at-risk body composition profiles. We examined the association of chemotherapy adverse events with several body composition measures, using alternative cut points from published studies.

METHODS

This is a retrospective study of women diagnosed with early breast cancer (EBC). Axial computerized tomography (CT) images from lumbar L3 segments were analyzed for the following body composition measures: myosteatosis (low Skeletal Muscle Density/SMD), sarcopenia (low Skeletal Muscle Index/SMI), and high Visceral Adipose Tissue (VAT). Adverse events during chemotherapy were dose reduction, early treatment discontinuation, and hospitalization. Log-binomial modeling was used to evaluate associations between body composition measures at different cut points with adverse events, adjusting for age, race, Body Mass Index/BMI, and comorbidities. Relative risks were reported as the measure of association.

RESULTS

In a sample of 338 women, mean age was 51, 14% were age 65 or older, 32% were non-white, 40% had obesity (/BMI ≥ 30 kg/m²), and mean number of comorbidities was 1.56. In multivariable analysis (MV), all three SMD cut points for myosteatosis had significant associations with total number of adverse events, as well as different cut points having significant associations with either dose reduction, early treatment discontinuation or hospitalization. SMI and VAT were not significant in the MV analysis; however, in some models, age and total comorbidities were significant for adverse events.

CONCLUSIONS

Among CT-derived measures of body composition, myosteatosis determined at any of three SMD cut points was associated with total and individual adverse events during chemotherapy for early breast cancer.

Prognostic Implication of Body Mass Index on Survival Outcomes in Surgically Treated Nonmetastatic Renal Cell Carcinoma: A Single-Institutional Retrospective Analysis of a Large Cohort

PURPOSE

Obesity is a well-known risk factor for renal cell carcinoma (RCC). However, the prognostic role of obesity in RCC has not been clearly established thus far. We aim to assess the effect of preoperative body mass index (BMI) on survival outcomes in nonmetastatic RCC patients.

PATIENTS AND METHODS

We retrospectively analyzed data on 2329 patients who underwent curative surgery for RCC between 2000 and 2014 in a single institution. Patients were divided into normal (< 23 kg/m²), overweight (23-24.9 kg/m²), and obese (≥ 25 kg/m²) groups depending on cutoffs for Asian population. Kaplan-Meier analysis with log-rank test was used to estimate and compare survival outcomes, including recurrence-free, overall, and cancer-specific survival, among each BMI group. The influence of BMI on each survival outcome was evaluated using multivariate Cox regression analyses.

RESULTS

Obese patients presented favorable 5-year recurrent-free (90.7% vs 84.9%, p < 0.001), overall (91.8% vs 86.8%, p = 0.002), and cancer-specific (94.8% vs 89.4%, p = 0.002) survival rates than the normal group. Multivariate analyses revealed that increasing BMI was an independent predictor of favorable survival outcomes (all p values < 0.05). In particular, overweight (p = 0.009) and obese (p = 0.009) patients showed better cancer-specific survival compared with normal patients.

CONCLUSIONS

Our data suggest that overweight and obesity defined based on BMI are generally related to favorable survival outcomes after surgery for RCC. Additional basic research is required to find out the biological mechanisms explaining the correlation between BMI and survival outcomes.

Clear cell renal cell carcinoma: the value of sex-specific abdominal visceral fat measured on CT for prediction of Fuhrman nuclear grade

OBJECTIVE

To explore whether sex-specific abdominal visceral fat composition on CT can predict the Fuhrman nuclear grade of clear cell renal cell carcinoma (ccRCC).

METHODS

One hundred seventy-one patients (123 males and 48 females) from four hospitals (multicentre group) and 159 patients (109 males and 50 females) from the cancer imaging archive (TCIA-KIRC group) with pathologically proven ccRCC (multicentre: 124 low grade and 47 high grade; TCIA-KIRC: 79 low grade and 80 high grade) were retrospectively included. Abdominal fat was segmented into subcutaneous fat area (SFA) and visceral fat area (VFA) on CT using ImageJ. The total fat area (TFA) and relative VFA (rVFA) were then calculated. Clinical characteristics (age, sex, waist circumference and maximum tumour diameter) were also assessed. Univariate and multivariate logistic regression analyses were performed to identify the association between general or sex-specific visceral fat composition and Fuhrman grade.

RESULTS

Females with high-grade ccRCC from the multicentre group had a higher rVFA (42.4 vs 31.3, p = 0.001) than those with low-grade ccRCC after adjusting for age. There was no significant difference in males. The rVFA remained a stable and independent predictor for females high-grade ccRCC in both the univariate (multicentre: OR 1.205, 95% CI 1.074-1.352, p = 0.001; TCIA-KIRC: OR 1.171, 95% CI 1.016-1.349, p = 0.029) and multivariate (multicentre: OR 1.095, 95% CI 1.024-1.170, p = 0.003; TCIA-KIRC: OR 1.103, 95% CI 1.024-1.187, p = 0.010) models.

CONCLUSIONS

Sex-specific visceral fat composition has different values for predicting high-grade ccRCC and could be used as an independent predictor for females with high-grade ccRCC.

KEY POINTS

• Visceral fat measurement (rVFA) as an independent predictor for high-grade ccRCC had good predictive power in females, but not in males. • Sex-specific visceral fat composition was significantly associated with high-grade ccRCC in females only. • The rVFA could be considered one of the risk factors for high-grade ccRCC for females.

The Importance of Body Composition in Explaining the Overweight Paradox in Cancer-Counterpoint

Despite a greater risk of cancer associated with higher BMI, overweight (BMI 25-<30 kg/m²) and class I obese (BMI 30-<35 kg/m²) patients often have a paradoxically lower risk of overall mortality after a cancer diagnosis, a phenomenon called the "obesity paradox." Only when patients exceed a BMI ≥35 kg/m² are elevations in mortality risk consistently noted. This paradox has been dismissed as the result of methodologic bias, which we will describe and debate here. However, even if such bias influences associations, there is growing evidence that body composition may in part explain the paradox. This phenomenon may more accurately be described as a BMI paradox. That is, BMI is a poor proxy for adiposity and does not distinguish muscle from adipose tissue, nor describe adipose tissue distribution. Low muscle mass is associated with higher risk of recurrence, overall and cancer-specific mortality, surgical complications, and treatment-related toxicities. Patients with who are overweight or obese have on average higher levels of muscle than their normal-weight counterparts. Also, there is some evidence that patients with moderate levels of subcutaneous adipose tissue may have lower mortality. More research utilizing body composition is needed to clarify the effects of adiposity on cancer mortality. Cancer Res; 78(8); 1906-12. ©2018 AACR.

The Plausibility of Obesity Paradox in Cancer-Point

In contrast to the convincing evidence that obesity (measured by body mass index, BMI) increases the risk of many different types of cancer, there is an ambiguity in the role of obesity in survival among cancer patients. Some studies suggested that higher BMI decreased mortality risk in cancer patients, a phenomenon called the obesity paradox. The spurious positive association between BMI and cancer survival is likely to be explained by several methodologic limitations including confounding, reverse causation, and collider stratification bias. Also, the inadequacy of BMI as a measure of body fatness in cancer patients commonly experiencing changes in body weight and body composition may have resulted in the paradox. Other factors contributing to the divergent results in literature are significant heterogeneity in study design and method (e.g., study population, follow-up length); time of BMI assessment (pre-, peri-, or post-diagnosis); and lack of consideration for variability in the strength and directions of associations by age, sex, race/ethnicity, and cancer subtype. Robust but practical methods to accurately assess body fatness and body compositions and weight trajectories in cancer survivors are needed to advance this emerging field and to develop weight guidelines to improve both the length and the quality of cancer survival. Cancer Res; 78(8); 1898-903. ©2018 AACR.

Preoperative Visceral Adiposity and Muscularity Predict Poor Outcomes after Hepatectomy for Hepatocellular Carcinoma

OBJECTIVE

Visceral adiposity, defined as a high visceral-to-subcutaneous adipose tissue area ratio (VSR), has been shown to be associated with poor outcomes in several cancers. However, in the surgical field, the significance of visceral adiposity remains controversial. The present study investigated the impact of visceral adiposity as well as sarcopenic factors (low muscularity) on outcomes in patients undergoing hepatectomy for hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

This retrospective study analyzed data from 606 patients undergoing hepatectomy for HCC at our institution between April 2005 and March 2016. Using preoperative plain computed tomography imaging at the level of the third lumbar vertebra, visceral adiposity, skeletal muscle mass, and muscle quality were evaluated by the VSR, skeletal muscle mass index (SMI), and intramuscular adipose tissue content (IMAC), respectively. The impact of these parameters on outcomes after hepatectomy for HCC was analyzed.

RESULTS

The overall survival rate was significantly lower among patients with a high VSR (p < 0.001) than among patients with a normal VSR. Similarly, the recurrence-free survival rate was significantly lower among patients with a high VSR (p = 0.016). A high VSR, low SMI, and high IMAC contributed to an increased risk of death (p < 0.001) and HCC recurrence (p < 0.001) in an additive manner. Multivariate analysis showed that not only preoperative low muscularity but also visceral adiposity was a significant risk factor for mortality (hazard ratio [HR] = 1.566, p < 0.001) and HCC recurrence (HR = 1.329, p = 0.020) after hepatectomy for HCC.

CONCLUSIONS

Preoperative visceral adiposity, as well as low muscularity, was closely related to poor outcomes after hepatectomy for HCC. It is crucial to establish a new strategy including perioperative nutritional interventions with rehabilitation for better outcomes after hepatectomy for HCC.

Usefulness of metabolic activity of adipose tissue in FDG PET/CT of colorectal cancer

PURPOSE

To determine the relationship between metabolic activity of adipose tissue on FDG PET/CT and prognosis in colorectal cancer.

METHODS

A total of 176 colorectal cancer patients with curative surgical resection were retrospectively enrolled. Volume and metabolic activity of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) on FDG PET/CT images were measured. The maximum standardized uptake value (SUV) of primary tumor (SUVtumor) was also obtained. Univariate analysis with log-rank test and multivariate Cox regression analyses were used to evaluate prognostic values of volume and metabolic activity of SAT and VAT as well as SUVtumor and clinicopathologic factors.

RESULTS

Of 176 patients, 26 experienced recurrence during follow-up. SUVtumor showed significant correlation with serum C-reactive protein level (r = 0.242, p = 0.001), SUV of VAT (r = 0.167, p = 0.026), and size of primary tumor (r = 0.341, p < 0.001). In univariate analysis with log-rank test, SUV of VAT (p = 0.009) and SAT (p = 0.006), volume of VAT (p = 0.015), N stage (p < 0.001), M stage (p < 0.001), tumor involvement of resection margin (p = 0.001), and lymphatic invasion (p = 0.024) were significantly associated with recurrence-free survival (RFS). However, SUVtumor showed no significant association with RFS. In multivariate Cox regression analysis, SUV of VAT (p = 0.016), presence of lymph node metastasis (p < 0.001), and tumor involvement of resection margin (p = 0.011) were independent prognostic factors for RFS.

CONCLUSIONS

The SUV of VAT in patients with colorectal cancer is significantly associated with FDG uptake of primary tumor. It is an independent predictor for RFS.

Visceral adiposity increases risk for hepatocellular carcinoma in male patients with cirrhosis and recurrence after liver transplant

Visceral adipose tissue (VAT) is a metabolically active organ, associated with higher risk of malignancies. We evaluated whether VAT is associated with the risk of hepatocellular carcinoma (HCC) in patients presenting with cirrhosis as well as HCC recurrence after liver transplantation (LT). Patients with cirrhosis (n = 678; 457 male) who were assessed for LT (289 with HCC) were evaluated for body composition analysis. Patients who underwent LT (n = 247, 168 male) were subsequently evaluated for body composition, and 96 of these patients (78 male) had HCC. VAT, subcutaneous adipose tissues, and total adipose tissues were quantified by computed tomography at the level of the third lumbar vertebra and reported as indexes (cross-sectional area normalized for height [square centimeters per square meter]). At the time of LT assessment, the VAT index (VATI) was higher in male patients with HCC compared to non-HCC patients (75 ± 3 versus 60 ± 3 cm² /m² , P = 0.001). The VATI, subcutaneous adipose tissue index, and total adipose tissue index were higher in male patients with HCC compared to non-HCC patients. By multivariate analysis, male patients with VATI ≥65 cm² /m² had a higher risk of HCC (hazard ratio, 1.90; 95% confidence interval, 1.31-2.76; P = 0.001). In male patients with HCC who underwent LT, a VATI ≥65 cm² /m² adjusted for Milan criteria was independently associated with higher risk of HCC recurrence (hazard ratio, 5.34; 95% confidence interval, 1.19-23.97; P = 0.03).

CONCLUSION

High VATI is an independent risk factor for HCC in male patients with cirrhosis and for recurrence of HCC after LT. (Hepatology 2018;67:914-923).

High perirenal fat thickness predicts a poor progression-free survival in patients with localized clear cell renal cell carcinoma

OBJECTIVES

The aim of the study was to assess the association between the progression-free survival (PFS) and perirenal fat thickness (PFT) in a population of histopathologically confirmed, localized clear cell renal cell carcinoma (ccRCC) patients.

METHODS

We retrospectively enrolled 174 patients with localized ccRCC at our center between December 2009 and December 2015. The preoperative visceral fat area (VFA), PFT, and subcutaneous fat area (SFA) were evaluated. Kaplan-Meier curves were used to assess the differences in PFS between the high and the low PFT groups within sexes. Potential independent prognostic factors of PFS were identified by univariable and multivariable Cox analyses.

RESULTS

During the follow-up period (median, 38 months), 27 patients (21 with high PFT and 6 with low PFT) experienced tumor progression. Kaplan-Meier curves revealed that high PFT was associated with a worse PFS than low PFT (P = 0.005). In the univariable Cox analyses, high VFA, high PFT, T stage, and the presence of sarcomatoid differentiation were significantly associated with a poor PFS. Moreover, both high PFT and VFA retained significance in the multivariable analysis.

CONCLUSION

We first report the evidence that high PFT presents as an independent risk factor of tumor progression in localized ccRCC. We suggest that this noninvasive and readily available preoperative parameter may help in the risk stratification of ccRCC patients before surgery.

Sarcopenia Predicts Prognosis in Patients with Newly Diagnosed Hepatocellular Carcinoma, Independent of Tumor Stage and Liver Function

Purpose

The purpose of this study was to demonstrate the prognostic significance of changes in body composition in patients with newly diagnosed hepatocellular carcinoma (HCC).

Materials and Methods

Patients (n=178) newly diagnosed with HCC participated in the study between 2007 and 2012. Areas of skeletal muscle and abdominal fat were directly measured using a three-dimensional workstation. Cox proportional-hazards modes were used to estimate the effect of baseline variables on overall survival. The inverse probability of treatmentweighting (IPTW) method was used to minimize confounding bias.

Results

Cutoff values for sarcopenia, obtained from receiver-operating characteristic curves, were defined as skeletal muscle index at the third lumbar vertebra of ≤ 45.8 cm/m² for males and ≤ 43.0 cm/m² for females. Sarcopenia patients were older, more likely to be female, and had lower body mass index. Univariable analysis showed that the presence of sarcopenia and visceral to subcutaneous fat area ratio (VSR) were significantly associatedwith prognosis. The multivariable analyses revealed that VSR was predictive of overall survival. However, in the multivariable Cox model adjusted by IPTW, sarcopenia, not VSR, were associated with overall survival.

Conclusion

The presence of sarcopenia at HCC diagnosis is independently associated with survival.

The association between renal sinus fat area and the progression-free survival in Chinese non-metastatic clear-cell renal cell carcinoma patients

In this retrospective study, we evaluated the association between renal sinus fat area (RSFA) and survival in 268 Chinese non-metastatic clear-cell renal cell carcinoma (ccRCC) patients. Patients with high RSFA exhibited better progression-free survival than those with low RSFA in both univariable (HR: 0.240; 95% CI: 0.119–0.482; p < 0.001) and multivariable (HR: 0.432; 95% CI: 0.369–2.749; p = 0.027) analyses. A propensity-score matched (PSM) analysis using Kaplan-Meier curves confirmed our findings (log-rank test; p = 0.028). Based on the multivariable analysis, we constructed a prognostic nomogram with 4 factors, namely, RSFA, Fuhrman grade, AJCC stage and sarcomatoid component. The c-index values for the Leibovich scoring system and the nomogram were 0.762 (95%CI, 0.688–0.835) and 0.823 (95%CI, 0.759–0.888), respectively. These findings demonstrate that high RSFA is associated with better progression-free survival in non-metastatic ccRCC.

Subcutaneous adiposity is an independent predictor of mortality in cancer patients

BACKGROUND

Prognostic significance of adiposity, at the time of cancer diagnosis, on survival is not clear. Body mass index (kg m^-2) does not provide an appropriate assessment of body composition; therefore, the concept of the 'obesity paradox' needs to be investigated based on the prognostic significance of fat and muscle. Independent prognostic significance of adipose tissue in predicting mortality, importance of visceral and subcutaneous adiposity in the presence and absence of sarcopenia on survival, was investigated.

METHODS

Adiposity markers including total adipose index (TATI), visceral adipose tissue index (VATI) and subcutaneous adipose tissue index (SATI) were estimated for 1473 gastrointestinal and respiratory cancer patients and 273 metastatic renal cell carcinoma patients using computed tomography. Univariate and multivariate analysis to determine mortality hazard ratios (HR) were conducted using cox proportional hazard models.

RESULTS

Low SATI (SATI <50.0 cm² m^-2 in males and <42.0 cm² m^-2 in females) independently associated with increased mortality (HR: 1.26; 95% CI: 1.11-1.43; P<0.001) and shorter survival (13.1 months; 95% CI, 11.4-14.7) compared to patients with high SATI (19.3 months; 95% CI, 17.6-21.0; P<0.001). In the presence of sarcopenia, the longest survival was observed in patients with high subcutaneous adiposity.

CONCLUSIONS

Subcutaneous adipose tissues appear to associate with reduction in mortality risk demonstrating the prognostic importance of fat distribution. The effect of sarcopenia on survival was more pronounced in patients with low subcutaneous adiposity.

Visceral adiposity and cancer survival: a review of imaging studies

Although obesity is a well-known risk factor for cancer, the association between obesity and cancer survival remains controversial. This is partially due to the inability of conventional obesity measures to directly assess adiposity or adipose tissue distribution. As a metabolic organ, visceral adipose tissue (VAT) secrets a variety of cytokines and cytokine-like factors, potentially affecting cancer survival. The objective of this review was to investigate the influence of imaging-assessed VAT on cancer survival. A total of 22 studies assessing the impact of visceral adiposity on survival were included. Negative associations between VAT and survival were more frequently observed among patients with colorectal (four of six studies) and pancreatic (three of five studies) cancers, compared to higher VAT predicting longer survival in most studies of renal cell carcinoma patients (four of five studies). Methodological limitations, including unstandardised VAT measurement methods, lack of other body composition measurement (i.e. muscle mass), small sample size and heterogeneous cohort characteristics, may explain controversial findings related to the impact of VAT on cancer survival.

Renal cell carcinoma: links and risks

This review provides an overview of the incidence of renal cell carcinoma (RCC) and a summary of the most commonly associated risk factors. A literature review was performed with a focus on recent studies with a high level of evidence (large prospective cohort studies and meta-analyses). The incidence rate of RCC varies globally, with the rate rising rapidly in more developed regions, demonstrating the effects of increased use of diagnostic imaging and prevalence of modifiable risk factors. Based on the current evidence, cigarette smoking, obesity, and hypertension are the most well-established risk factors for sporadic RCC worldwide. Acquired cystic kidney disease is also a significant risk factor, specifically in dialysis patients. There is increasing evidence for an inverse association between RCC risk and moderate alcohol consumption. Certain analgesics and occupational exposure have been linked to an increased risk of RCC, although data are limited. Diets rich in fruits and vegetables may provide a protective effect.

Obesity and Kidney Cancer

Renal cell cancer (RCC) is the major type of kidney cancer with increasing incidence. Obesity is one of the well-established risk factors for RCC. Meta-analyses including multiple cohort and case-control studies have found a consistent positive association between obesity and RCC. The association appeared to be independent of other RCC risk factors including hypertension and has been often stronger in women, although a positive association has also been observed in men. Obesity has been largely measured as body mass index (BMI). Studies which evaluated other measures of obesity including waist circumference (WC), waist-to-hip ratio (WHR) as well as increase in weight have reported similar positive associations with RCC. Although the mechanisms by which obesity influences renal carcinogenesis have been under-explored, insulin resistance and certain growth factors including insulin-like growth factor (IGF-1), sex steroid hormones, and biochemical markers such as adiponectin may be involved. The positive association with obesity has been observed with the clear cell type of RCC, which is the major histological subtype. On the other hand, the association between obesity and RCC survival appears to be much more complex. An apparent inverse association between obesity at time of diagnosis and RCC survival has been observed in some studies' generating speculation of an "obesity paradox" hypothesis. However, this "paradox" may be due to reverse causation, selection bias, or other forms of bias rather than a true biological association.