Association between metabolically healthy obesity and metastasis in lung cancer patients - a systematic review and meta-analysis

Background

Many clinical trials have looked at the relationship between obesity and lung cancer (LC), however, there is scarcity of literature specifically addressing the association between metabolically healthy obesity and metastasis in LC patients. To address this gap in the body of evidence, the study was conducted to observe the association between metabolically healthy obesity and metastasis in LC patients.

Methods

We conducted a pre-registered systematic review by searching six major online databases to identify studies relevant related to our investigation, in adherence with the PRISMA guidelines. A proper data extraction protocol was further established to synthesize the findings from the selected papers through a meta-analysis.

Results

Eleven (11) studies met the requisite selection criterion and were included in the study. A random-effect model was used. Obesity was found to have a significant impact on readmission in LC patients. The combined analysis showed a significant effect size of 0.08 (95% CI 0.07 to 0.08), indicating a noticeable impact of obesity. It was also assessed that obese individuals had a 34% reduced risk of LC compared to normal weight individuals. Obesity was associated with a lower risk of surgical complications with a pooled risk ratio of 0.13 (95% CI 0.12 to 0.14). A statistically significant decreased risk of LC (pooled RR = 0.72, 95% CI: 0.68 to 0.77) was also observed in the obese individuals.

Conclusion

The analysis reveals that obesity is associated with a noticeable increase in readmissions, although the impact on LC risk itself is negligible. Moreover, obesity appears to have a beneficial effect by reducing the risk of surgical complications. These results highlight the complex relationship between the two aforementioned factors, emphasizing the importance of considering obesity as a significant factor in patient management and healthcare decision-making.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42023427612.

The Influence of Preoperative Nutritional and Systemic Inflammatory Status on Perioperative Outcomes following Da Vinci Robot-Assisted Thoracic Lung Cancer Surgery

Background: Nutrition is an important factor in the outcome of any disease process. We evaluated the relationship of nutritional status and inflammatory status of non-small cell lung cancer (NSCLC) patients undergoing robotic-assisted thoracic surgery (RATS) with postoperative complications. Methods: This prospective cohort study included 107 NSCLC patients undergoing surgical treatment, between 2019 and 2021. Nutritional status and inflammatory status were assessed before pulmonary resection using anthropometric assessment, blood tests, and body mass index (BMI). Results: The BMI was 27.5 ± 4.4. Based on BMI, 29% (n = 31) were classified as normal weight, 43% (n = 46) as overweight, and 28% (n = 30) as obese. The mean neutrophil/lymphocyte ratio (NLR) was 2.16 ± 0.85, the platelet/lymphocyte ratio (PLR) was 121.59 ± 44.21, and the lymphocyte/monocyte ratio (LMR) was 3.52 ± 1.17. There was no increase in the number of intraoperative complications or bleeding (p = 0.696), postoperative complications (p = 0.569), mean hospital stay (p = 0.258) or duration of chest drain (p = 0.369). Higher inflammatory status, with an NLR > 1.84, was associated with more overall postoperative complications (p = 0.028), only in univariate analysis, but this significance was not maintained on multivariate analysis. Conclusions: BMI was not a predictor of increased postoperative risk in this cohort; therefore, weight should not deter surgeons from using RATS for pulmonary resection.

HALP score and GNRI: Simple and easily accessible indexes for predicting prognosis in advanced stage NSCLC patients. The İzmir oncology group (IZOG) study

Objective

The Hemoglobin, Albumin, Lymphocyte, and Platelet (HALP) Score and the Geriatric Nutrition Risk Index (GNRI) are used as prognostic factors in different types of cancers. In this study we analyzed the prognostic value of the HALP Score and the GNRI calculated prior to first-line treatment in patients diagnosed with de novo metastatic non-small cell lung cancer (mNSCLC).

Materials and methods

De novo mNSCLC patients were retrospectively evaluated from January 2016 to December 2019. Patients with Driver’s mutation, severe comorbidities, active infection, or insufficient organ function, and those receiving anti-inflammatory treatment were excluded from the study. Optimal cut-off points for the HALP score and the GNRI were calculated with the receiver operating characteristic (ROC) curve analysis. Predictive factors for overall survival (OS) were assessed with univariate and multivariate Cox proportional hazard analyses, and OS was studied with the Kaplan–Meier analysis.

Results

The study included 401 patients in total. In the ROC curve analysis, the cut-off points were found 23.24 (AUC = 0.928; 95% CI: 0.901–0.955, p < 0.001) for HALP, and 53.60 (AUC = 0.932; 95% CI: 0.908–0.955, p < 0.001) for GNRI. Groups with lower HALP scores and lower GNRI had significantly shorter OS compared to those with higher HALP scores and GNRIs. Univariate analysis showed that male gender, smoking, high ECOG score, low HALP score and low GNRI were associated with worse survival rates. Multivariate analysis showed that low HALP score (HR = 2.988, 95% CI: 2.065–4.324, p < 0.001); low GNRI score (HR = 2.901, 95% CI: 2.045–4.114, p < 0.001) and smoking history (HR = 1.447, 95% CI: 1.046–2.001, p = 0.025) were independent factors associated with worse OS rates.

Conclusion

Our study showed the HALP score and the GNRI to be of prognostic value as simple, cost-effective, and useful markers that predict OS in de novo mNSCLC patients.

A scoring system to predict the risk of major complications after laparoscopic liver resection in elderly patients with hepatocellular carcinoma

BACKGROUND

The safety of laparoscopic liver resection (LLR) in elderly patients is a matter of concern because the reduced physiologic reserve increases the risk of postoperative complications. However, there are few score systems for predicting complications after LLR in elderly patients. The aim of this study is to propose a new simplified scoring system based on the Geriatric Nutritional Risk Index (GNRI) to predict major complications after LLR in elderly patients with hepatocellular carcinoma (HCC).

METHODS

We retrospectively reviewed 257 consecutive patients aged ≥ 65 years who underwent LLR for HCC between 2004 and 2019. The GNRI formula was 1.489 × serum albumin (g/L) + 41.7 × present weight/ideal weight (kg). A scoring system to predict the risk of major complications was developed by assigning points to each risk factor equal to its regression coefficient determined in the multivariable analysis. Major complications were defined as complications of Clavien-Dindo grade III or higher.

RESULTS

Of the 257 patients, 219 patients were finally included in this study. Major complications occurred after LLR in 24 patients (10.9%). Multivariable analysis showed that the GNRI (hazard ratio [HR] 3.396, 95% confidence interval [CI] 1.242-9.288, P = 0.017), Child-Turcotte-Pugh score (HR 2.191, 95% CI 1.400-8.999, P = 0.036), major liver resection (HR 2.683, 95% CI 1.082-7.328, P = 0.050), and intraoperative transfusion (HR 1.802, 95% CI 1.428-7.591, P = 0.022) were independent predictors of major postoperative complications. These variables were assigned points based on their HRs, and the resulting 10-point model showed good discrimination (area under the curve 0.756, 95% CI 0.649-0.836, P = 0.001).

CONCLUSION

The scoring system outperformed the GNRI for predicting major complications after LLR in elderly patients with HCC.

"Obesity paradox" has not an impact on minimally invasive anatomical lung resection

INTRODUCTION

The paradoxical benefit of obesity, the 'obesity paradox', has been analyzed in lung surgical populations with contradictory results. Our goal was assessing the relationship of body mass index (BMI) to acute outcomes after minimally invasive major pulmonary resections.

METHODS

Retrospective review of consecutive patients who underwent pulmonary anatomical resection through a minimally invasive approach for the period 2014-2019. Patients were grouped as underweight, normal, overweight and obese type I, II and III. Adjusted odds ratios regarding postoperative complications (overall, respiratory, cardiovascular and surgical morbidity) were produced with their exact 95% confidence intervals. All tests were considered statistically significant at p<0.05.

RESULTS

Among 722 patients included in the study, 37.7% had a normal BMI and 61.8% were overweight or obese patients. When compared with that of normal BMI patients, adjusted pulmonary complications were significantly higher in obese type I patients (2.6% vs 10.6%, OR: 4.53 [95%CI: 1.86-12.11]) and obese type II-III (2.6% vs 10%, OR: 6.09 [95%CI: 1.38-26.89]). No significant differences were found regarding overall, cardiovascular or surgical complications among groups.

CONCLUSIONS

Obesity has not favourable effects on early outcomes in patients undergoing minimally invasive anatomical lung resections, since the risk of respiratory complications in patients with BMI≥30kg/m² and BMI≥35kg/m² is 4.5 and 6 times higher than that of patients with normal BMI.

Exploring the Impact of the Obesity Paradox on Lung Cancer and Other Malignancies

Simple Summary

Studies have shown that obesity is associated with many adverse health effects, including worse cancer outcomes. Many studies paradoxically suggest a survival benefit for obesity in treatment outcomes of cancers such as non-small-cell lung cancer. This relationship is not seen in animal models. We hypothesize that this relationship is secondary to suboptimal quantification of adiposity, enhanced immunotherapy response, and variables such as sex, medications, and smoking status. There are many ways to measure and classify adiposity, but the ability to distinguish abdominal obesity is likely key in predicting accurate prognosis. There are many ways obesity impacts cancer treatment course from diagnosis to survivorship. In this paper, we aim to analyze the factors contributing to the obesity paradox and its effect on lung cancer. This can aid the treatment and prognosis of lung cancer and may support further research into obesity-specific impacts on this malignancy.

Abstract

There is a paradoxical relationship between obesity, as measured by BMI, and many types of cancer, including non-small-cell lung cancer. Obese non-small-cell lung cancer patients have been shown to fare better than their non-obese counterparts. To analyze the multifaceted effects of obesity on oncologic outcomes, we reviewed the literature on the obesity paradox, methods to measure adiposity, the obesity-related derangements in immunology and metabolism, and the oncologic impact of confounding variables such as gender, smoking, and concomitant medications such as statins and metformin. We analyzed how these aspects may contribute to the obesity paradox and cancer outcomes with a focus on lung cancer. We concluded that the use of BMI to measure adiposity is limited and should be replaced by a method that can differentiate abdominal obesity. We also concluded that the concomitant metabolic and immunologic derangements caused by obesity contribute to the obesity paradox. Medications, gender, and smoking are additional variables that impact oncologic outcomes, and further research needs to be performed to solidify the mechanisms.

Does morbid obesity influence perioperative outcomes after video-assisted thoracic surgery (VATS) lobectomy for non-small cell lung cancer? Analysis of the Italian VATS group registry

OBJECTIVES

Obesity in Europe, and worldwide, has been an increasing epidemic during the past decades. Moreover, obesity has important implications regarding technical issues and the risks associated with surgical interventions. Nevertheless, there is a lack of evidence assessing the influence of obesity on video-assisted thoracic surgery (VATS) lobectomy results. Our study aimed to assess the impact of morbid obesity on perioperative clinical and oncological outcomes after VATS lobectomy using a prospectively maintained nationwide registry.

METHODS

The Italian VATS lobectomy Registry was used to collect all consecutive cases from 55 Institutions. Explored outcome parameters were conversion to thoracotomy rates, complication rates, intra-operative blood loss, surgical time, hospital postoperative length of stay, chest tube duration, number of harvested lymph-node, and surgical margin positivity.

RESULTS

From 2016 to 2019, a total of 4412 patients were collected. 74 patients present morbid obesity (1.7%). Multivariable-adjusted analysis showed that morbid obesity was associated with a higher rate of complications (32.8% vs 20.3%), but it was not associated with a higher rate of conversion, and surgical margin positivity rates. Moreover, morbid obesity patients benefit from an equivalent surgical time, lymph-node retrieval, intraoperative blood loss, hospital postoperative length of stay, and chest tube duration than non-morbid obese patients. The most frequent postoperative complications in morbidly obese patients were pulmonary-related (35%).

CONCLUSION

Our results showed that VATS lobectomy could be safely and satisfactorily conducted even in morbidly obese patients, without an increase in conversion rate, blood loss, surgical time, hospital postoperative length of stay, and chest tube duration. Moreover, short-term oncological outcomes were preserved.

"Obesity paradox" has not an impact on minimally invasive anatomical lung resection

INTRODUCTION

The paradoxical benefit of obesity, the 'obesity paradox', has been analyzed in lung surgical populations with contradictory results. Our goal was assessing the relationship of body mass index (BMI) to acute outcomes after minimally invasive major pulmonary resections.

METHODS

Retrospective review of consecutive patients who underwent pulmonary anatomical resection through a minimally invasive approach for the period 2014-2019. Patients were grouped as underweight, normal, overweight and obese type I, II and III. Adjusted odds ratios regarding postoperative complications (overall, respiratory, cardiovascular and surgical morbidity) were produced with their exact 95% confidence intervals. All tests were considered statistically significant at p<0.05.

RESULTS

Among 722 patients included in the study, 37.7% had a normal BMI and 61.8% were overweight or obese patients. When compared with that of normal BMI patients, adjusted pulmonary complications were significantly higher in obese type I patients (2.6% vs 10.6%, OR: 4.53 [95%CI: 1.86-12.11]) and obese type II-III (2.6% vs 10%, OR: 6.09 [95%CI: 1.38-26.89]). No significant differences were found regarding overall, cardiovascular or surgical complications among groups.

CONCLUSIONS

Obesity has not favourable effects on early outcomes in patients undergoing minimally invasive anatomical lung resections, since the risk of respiratory complications in patients with BMI≥30kg/m2 and BMI≥35kg/m2 is 4.5 and 6 times higher than that of patients with normal BMI.

Geriatric nutritional risk index predicts cancer prognosis in patients with local advanced rectal cancer undergoing chemoradiotherapy followed by curative surgery

Aim

The clinical significance of the geriatric nutritional risk index (GNRI) in locally advanced rectal cancer (LARC) patients undergoing preoperative chemoradiotherapy (CRT) followed by curative surgery has not been comprehensively evaluated.

Methods

This retrospective study enrolled 93 LARC patients diagnosed with clinical lymph node metastasis. The GNRI formula was as follows: 1.489 × albumin (g/l) + 41.7 × current weight/ideal weight. Patients were categorized as GNRI low (GNRI < 104.25) or high (GNRI > 104.25) according to the receiver operating characteristic (ROC) curve for survival analysis. The impact of GNRI status on the prognostic outcomes of curative surgery for LARC was examined.

Results

There were 55 (59.14%) and 38 (40.86%) patients in the GNRI high and low groups, respectively. Of the investigated demographic factors, age, pathological tumor invasion, and presence of recurrence were significantly associated with the GNRI value. In Kaplan–Meier analysis, overall survival (OS) and disease-free survival (DFS) were significantly shorter in the GNRI low group (OS: p = 0.00020, DFS: p = 0.0044, log-rank test). Multivariate analysis using a Cox proportional hazards model showed that a low GNRI was an independent risk factor for poor OS (hazard ratio (HR) = 3.22; 95% confidence interval (CI), 1.37–8.23; p = 0.0068) and DFS (HR = 2.32; 95%CI = 1.15–4.79; p = 0.018). Although use of adjuvant therapy has no impact on prognosis (OS: p = 0.26, DFS: p = 0.29), low GNRI showed shorter OS and DFS in patients with pathological lymph node metastasis [ypN(+)] (OS: p = 0.033, DFS: p = 0.032, log-rank test).

Conclusions

GNRI is a useful marker for LARC patients diagnosed with clinical lymph node metastasis and treated by preoperative CRT followed by curative surgery. GNRI is a useful tool to identify high risk of recurrence for improving the survival in LARC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02139-z.

The Effect of Body Mass Index on Treatment Outcomes in Patients with Metastatic Non-Small Cell Lung Cancer Treated with Platinum-Based Therapy

To investigate the effect of body mass index(BMI) on treatment outcomes and side-effect profile in metastatic non-small cell lung cancer(NSCLC) patients receiving platinum-based chemotherapy(ChT) in the first-line setting. This was a retrospective analysis of 233 NSCLC patients who were treated and followed up from 2008 through 2018. NSCLC patients who had metastatic disease at the time of diagnosis and were treated with platinum-based ChT in the first-line setting were included. The patients were divided into 2 groups based on the BMI as follows; BMI < 25 kg/m² and BMI ≥ 25 kg/m². This retrospective analysis enrolled 233 patients, 35 (15.0%) of whom were female. The BMI in 132 patients (56.2%) was < 25 kg/m². The median age was 58 years (range, 21-90). Median progression-free survival(PFS) was 7 mo, in the patients with BMI ≥ 25 kg/m² compared to 5.0 mo, in those with BMI < 25 kg/m² (p = 0.032), with corresponding median overall survival(OS) durations of 12 vs. 9 mo, (p = 0.003). In multivariate analysis, ECOG PS 2, grade III histology, and brain or bone metastasis negatively affected OS, whereas BMI ≥ 25 kg/m² positively affected OS. A high BMI prior to therapy in patients with NSCLC treated with platinum-based ChT in the first-line setting was associated with more favorable PFS and OS.

Oncologic Outcomes of Surgery Versus SBRT for Non-Small-Cell Lung Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

The optimal treatment of stage I non-small-cell lung carcinoma is subject to debate. The aim of this study was to compare overall survival and oncologic outcomes of lobar resection (LR), sublobar resection (SR), and stereotactic body radiotherapy (SBRT).

METHODS

A systematic review and meta-analysis of oncologic outcomes of propensity matched comparative and noncomparative cohort studies was performed. Outcomes of interest were overall survival and disease-free survival. The inverse variance method and the random-effects method for meta-analysis were utilized to assess the pooled estimates.

RESULTS

A total of 100 studies with patients treated for clinical stage I non-small-cell lung carcinoma were included. Long-term overall and disease-free survival after LR was superior over SBRT in all comparisons, and for most comparisons, SR was superior to SBRT. Noncomparative studies showed superior long-term overall and disease-free survival for both LR and SR over SBRT. Although the papers were heterogeneous and of low quality, results remained essentially the same throughout a large number of stratifications and sensitivity analyses.

CONCLUSION

Results of this systematic review and meta-analysis showed that LR has superior outcomes compared to SBRT for cI non-small-cell lung carcinoma. New trials are underway evaluating long-term results of SBRT in potentially operable patients.

Psoas muscle mass in patients undergoing lung cancer surgery: a prognostic difference between squamous cell carcinoma and adenocarcinoma

BACKGROUND

Psoas muscle mass is a surrogate marker for sarcopenia: a depletion of skeletal muscle mass. This study was conducted to elucidate the prognostic significance of the psoas muscle index (PMI: cross-sectional area of the bilateral psoas muscle at the umbilical level on computed tomography/height² [cm²/m²]) in patients undergoing surgery for lung squamous cell carcinoma (SCC) and lung adenocarcinoma (ADC).

METHODS

One hundred and sixty-five patients with SCC and 556 patients with ADC who underwent R0 resection between 2007 and 2014 were reviewed for analysis. In SCC patients, the mean value (standard deviation) of the PMI was 6.15 (1.49) in men and 4.65 (1.36) in women. Among ADC patients, the PMI was 7.12 (1.60) in men and 5.29 (1.22) in women. Clinicopathological characteristics as well as the survival were evaluated.

RESULTS

The PMI was associated with the age, body mass index (BMI), and serum albumin. In the multivariable Cox regression analysis, after adjusting for age, BMI, serum albumin, sex, pathological stage, and diffusing capacity for carbon monoxide, the PMI showed a significant association with the overall survival (OS) and disease-free survival (DFS) in SCC patients (hazard ratios 0.50 and 0.56, 95% confidence intervals 0.39-0.65 and 0.45-0.71, respectively). On the other hand, in ADC patients, the PMI had no impact on the OS or DFS.

CONCLUSIONS

The PMI was significantly associated with the survival of lung SCC patients, but not of lung ADC patients, suggesting the presence of a previously unidentified relationship between skeletal muscle and lung SCC progression.

Body Mass Index (BMI), BMI Change, and Overall Survival in Patients With SCLC and NSCLC: A Pooled Analysis of the International Lung Cancer Consortium

INTRODUCTION

The relationships between morbid obesity, changes in body mass index (BMI) before cancer diagnosis, and lung cancer outcomes by histology (SCLC and NSCLC) have not been well studied.

METHODS

Individual level data analysis was performed on 25,430 patients with NSCLC and 2787 patients with SCLC from 16 studies of the International Lung Cancer Consortium evaluating the association between various BMI variables and lung cancer overall survival, reported as adjusted hazard ratios (aHRs) from Cox proportional hazards models and adjusted penalized smoothing spline plots.

RESULTS

Overall survival of NSCLC had putative U-shaped hazard ratio relationships with BMI based on spline plots: being underweight (BMI < 18.5 kg/m2; aHR = 1.56; 95% confidence interval [CI]:1.43-1.70) or morbidly overweight (BMI > 40 kg/m2; aHR = 1.09; 95% CI: 0.95-1.26) at the time of diagnosis was associated with worse stage-specific prognosis, whereas being overweight (25 kg/m2 ≤ BMI < 30 kg/m2; aHR = 0.89; 95% CI: 0.85-0.95) or obese (30 kg/m2 ≤ BMI ≤ 40 kg/m2; aHR = 0.86; 95% CI: 0.82-0.91) was associated with improved survival. Although not significant, a similar pattern was seen with SCLC. Compared with an increased or stable BMI from the period between young adulthood until date of diagnosis, a decreased BMI was associated with worse outcomes in NSCLC (aHR = 1.24; 95% CI: 1.2-1.3) and SCLC patients (aHR=1.26 (95% CI: 1.0-1.6). Decreased BMI was consistently associated with worse outcome, across clinicodemographic subsets.

CONCLUSIONS

Both being underweight or morbidly obese at time of diagnosis is associated with lower stage-specific survival in independent assessments of NSCLC and SCLC patients. In addition, a decrease in BMI at lung cancer diagnosis relative to early adulthood is a consistent marker of poor survival.

The Effect of Body Mass Index on Pulmonary Related Debility Rehabilitation

BACKGROUND

Obesity is a known factor for the development of abnormal respiratory physiology. However, several studies have found that obesity does not hinder functional recovery in patients hospitalized for postacute care following a stroke or cardiovascular event. This study was designed to determine the effect of overweight and obesity on patients with acute pulmonary disease, hospitalized in an inpatient rehabilitation facility (IRF).

OBJECTIVE

To investigate the impact of body mass index (BMI) on indices of function, specifically, the functional independence measure (FIM) among patients with pulmonary related debility admitted to a rehabilitation hospital.

DESIGN

Retrospective cohort study.

SETTING

Pulmonary unit in an acute freestanding rehabilitation hospital.

PATIENTS

All patients admitted to an IRF with a diagnosis of pulmonary related debility over a 6-year period.

METHODS

The data used in the study included the patient height and weight (measured on admission) and FIM (scored on admission and discharge).

MAIN OUTCOME MEASURES

The primary study outcome measure was the change in FIM per day by the patients' BMI category.

RESULTS

For the 381 patients admitted during the observation period, BMI was compared with FIM score changes per day (FIM efficiency). After adjusting for age and sex, the FIM efficiency only slightly differed by BMI, failing to reach statistical significance. However, age did significantly influence the outcome (P = .05).

CONCLUSION

This study demonstrates that among a large group of patients with a pulmonary related debility, there was no statistically significant correlation between BMI and FIM efficiency. The overweight patients were similar in progression to those who were underweight, normal weight, and obese. However, this study found that increased age adversely affected the outcome of rehabilitation.

LEVEL OF EVIDENCE

III.

Atrial fibrillation in patients with active malignancy and use of anticoagulants: Under-prescription but no adverse impact on all-cause mortality

Prescription of anticoagulants (ACs) in patients with cancer and atrial fibrillation (AF) is challenging and the impact on survival is not defined. In this study data prospectively collected in Oncology Units were retrospectively evaluated. Among 4664 patients admitted for malignancy, 394 patients (8.4%) had documented AF (mean age of 74 ± 9) and AC was prescribed to 155 patients (40%). Neither the type of cancer, the stage of the disease (metastatic or not) nor the ongoing treatments were significantly associated with prescription of AC, which was independently associated with BMI (OR 1.10; CI 95% 1.03-1.17; p = .003), valvular heart disease (OR 3.76; CI95% 1.59-8.87; p = .002), and previous venous thromboembolism (OR 6.67; 95%CI 2.67-16.70; p < .001). During a median follow-up of 212 days, survival from all-cause death was 37%, 28% and 18% at 6 months, 1 and 2 years, respectively. Only variables related to neoplastic disease or to patient clinical complexity were independently associated with mortality. A CHA₂DS₂VASc ≥ 4 was significantly associated with mortality (HR 1.33; 95%CI 1.06-1.67; p = .013). Treatment with ACs was not significantly related to mortality, neither in the whole cohort of patients, nor in patients with metastatic malignancies. In conclusion the prescription of ACs in patients with AF and active cancer was suboptimal, with one fourth of the patients not treated with ACs and one third using LMWH at prophylactic, non-therapeutic doses. Only few variables (BMI, valvular heart disease and previous venous thromboembolism) predicted prescription of ACs. Prescription of ACs was not associated with all-cause mortality, even in the subgroup with metastasis.

Impact of body mass index on long-term survival outcome in Asian populations with solid cancer who underwent curative-intent surgery: A six-year multicenter observational cohort study

Purpose: Being elevated body mass index (BMI) has been considered a poor prognostic factor in patients with cancer. However, studies about the impact of elevated BMI on the survival outcome after cancer surgery have conflicting results. This study aimed to evaluate the impact of BMI on long-term postoperative survival outcome in a large cohort of Asian population with solid cancers. Methods: A total of 33,551 patients who underwent curative-intent surgery for solid cancers between January 2007 and December 2012 at four hospitals in Taiwan were included. BMI was analyzed using univariate and multivariate regression analyses to determine its association with survival outcome. Results: With a median follow-up of 43.8 (range, 1-91) months, the rate of all-cause mortality was 21.7% (n=7264 patients), while that of cancer-related mortality was 13.4% (n=4499 patients). BMI was a significant prognostic factor in multivariate analysis for overall survival (OS) and cancer-specific survival (CSS). The adjusted hazard ratio (HR) per kg/m² was 0.922 (95% confidence interval [CI], 0.916-0.929; P<0.001) and 0.932 (95% CI, 0.924-0.940; P<0.001) for OS and CSS, respectively. Patients with BMI <17 kg/m² had the highest postoperative mortality risk, with a hazard ratio of 3.8-fold higher for OS and 5.0-fold higher for CSS than those with BMI >35 kg/m². Conclusions: This study showed that BMI was positively associated with survival outcome in patients with cancer who underwent radical surgery. BMI was an independent prognostic factor and can be used to risk stratify patients in Asians with solid cancers.

Clinical depression and anxiety among ST-elevation myocardial infarction hospitalizations: Results from Nationwide Inpatient Sample 2004-2013

Depression and anxiety are common among patients who have a major cardiovascular event. However, despite their frequency, there is a lack of evidence regarding the relationship between depression and/or anxiety and receiving revascularization in ST-elevation myocardial infarction (STEMI) hospitalizations. Using data from the Nationwide Inpatient Sample (NIS) from the years 2004 to 2013, we assessed whether a clinical co-diagnosis of depression and/or anxiety decreases the likelihood of revascularization among STEMI hospitalizations. Our central finding is that, paradoxically, the odds of in-hospital mortality were lower among STEMI hospitalizations with a clinical co-diagnosis of depression and/or anxiety as compared to those without. We further discovered that clinical diagnoses of depression and/or anxiety were less prevalent among revascularized as compared to non-revascularized STEMI hospitalizations. However, the percentage of clinical diagnoses of depression and/or anxiety among STEMI hospitalizations increased at a similar rate over a 10-year period irrespective of revascularization status. In conclusion, these results are suggestive of the potentially underdiagnosed mental health issues surrounding major cardiovascular events, and indeed, chronic disease as a whole. To our knowledge, this is the first study to document and examine the "depression paradox" among a population of cardiac patients.

Thoracic Surgery Considerations in Obese Patients

The obesity epidemic in the United States has increased greatly over the past several decades, and thoracic surgeons are likely to see obese patients routinely in their practices. Obesity has direct deleterious health effects such as metabolic disorder and cardiovascular disease, and is associated with many cancers. Obese patients who need thoracic surgery pose practical challenges to many of the routine elements in perioperative management. Preoperative assessment of obesity-related comorbid conditions and risk stratification for surgery, thorough intraoperative planning for anesthesia and surgery, and postoperative strategies to optimize pulmonary hygiene and mobility minimize the risk of adverse outcomes.

Association of body mass index and outcomes following lobectomy for non-small-cell lung cancer

Background

Obesity and overweight have become increasingly prevalent, but no consensus has been reached regarding the effect of body mass index (BMI) on surgical outcomes. In this study, we sought to examine the influence of BMI on perioperative outcomes in a large cohort of patients with non-small-cell lung cancer (NSCLC) who underwent lobectomy.

Methods

A retrospective study was conducted in 1198 patients who underwent lobectomy for primary NSCLC at Shandong Provincial Hospital between November 2006 and January 2017. BMI was calculated using measured height and weight on admission and categorized as obese (≥ 30 kg/m²), overweight (25 to 29.9 kg/m²), normal (18.5 to 24.9 kg/m²), or underweight (< 18.5 kg/m²). Patients’ baseline characteristics and outcomes were abstracted from medical records following institutional review board approval. Endpoints included operative mortality, perioperative complications, and length of stay (LOS). Complications were divided into four groups as respiratory, cardiovascular, other, and overall. Logistic regression models were constructed to assess the association between BMI and adverse outcomes.

Results

When compared with normal BMI, obesity and overweight did not increase the risk of complications in any category, operative mortality, or prolonged LOS. In fact, the incidence of operative mortality and respiratory complications tended to be lower in overweight patients than in normal weight patients (P = 0.047 and P = 0.041, respectively). Conversely, underweight patients experienced significantly more operative mortality, respiratory complications, and prolonged LOS (P = 0.004, P = 0.011, and P = 0.003, respectively).

Conclusions

Obesity and overweight did not confer adverse surgical outcomes. Underweight patients presented increased risk of respiratory complications, perioperative death, and prolonged LOS. Thus, overweight and obesity should not be a relative contraindication for lobectomy. Meanwhile, nurses and surgeons should focus on perioperative management of underweight patients.

The obesity paradox in cancer: clinical insights and perspectives

A series of evidence demonstrated that obesity represents an established risk factor for an increase in the incidence of multiple cancer types and for poor cancer survival. Nevertheless, recent studies suggested that, in a series of cancers, patients with a normal body mass index (BMI) have worse outcomes than obese patients. This phenomenon, named 'obesity paradox' or 'reverse epidemiology' in cancer, is not well understood and presents controversial aspects. Therefore, this review aims to explore the available studies concerning the relationship between obesity and cancer incidence or survival and to highlight the hypothetical explanations and the methodological framework. In this regard, we underline the limits of BMI as a potential marker of adiposity and the relevance to assessing body composition, beyond the body size. Further studies are needed to define the impact of obesity in cancer patients, to tailor weight management after cancer diagnosis and to hopefully improve overall clinical outcome.

Systematic review of prognostic roles of body mass index for patients undergoing lung cancer surgery: does the 'obesity paradox' really exist?

Summary

The paradoxical benefit of obesity, the 'obesity paradox', has been recently identified in surgical populations. Our goal was to evaluate by a systematic review with meta-analysis the prognostic role of body mass index (BMI) and to identify whether the 'obesity paradox' exists in lung cancer surgery. Comprehensive literature retrieval was conducted in PubMed to identify the eligible articles. The odds ratios (OR) and hazard ratios (HR) with the corresponding 95% confidence intervals (CI) were used to synthesize in-hospital and long-term survival outcomes, respectively. The heterogeneity level and publication bias between studies were also estimated. Finally, 25 observational studies with 78 143 patients were included in this review. The pooled analyses showed a significantly better long-term survival rate in patients with higher BMI, but no significant benefit of increased BMI was found for in-hospital morbidity. The pooled analyses also showed that overall morbidity (OR: 0.84; 95% CI: 0.73-0.98; P  =   0.025) and in-hospital mortality (OR: 0.78; 95% CI: 0.63-0.98; P  =   0.031) were significantly decreased in obese patients. Obesity could be a strong predictor of the favourable long-term prognosis of lung cancer patients (HR: 0.69; 95% CI: 0.56-0.86; P  =   0.001). The robustness of these pooled estimates was strong. No publication bias was detected. In summary, obesity has favourable effects on in-hospital outcomes and long-term survival of surgical patients with lung cancer. The 'obesity paradox' does have the potential to exist in lung cancer surgery.

Influence of body mass index on the therapeutic efficacy of gemcitabine plus cisplatin and overall survival in lung squamous cell carcinoma

Background

Gemcitabine plus cisplatin (GP) is commonly used to treat lung squamous cell carcinoma (SCC); however, it is not clear which subgroup of lung SCC patients could benefit most from GP treatment. We explored the predictive factors in lung SCC patient cohorts.

Methods

Seventy‐eight lung SCC patients treated with a first‐line GP regimen were enrolled in this retrospective cohort study. Progression‐free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Classification tree models were used to explore the risk factors for PFS and OS in these patients.

Results

The median PFS and OS in SCC patients treated with a GP regimen were 6.0 and 13.6 months, respectively. Three terminal subgroups were formed for both PFS and OS. The subgroup with a body mass index (BMI) > 23.94 kg/m² and aged ≤ 54.5 had the longest PFS (9.0 months); the subgroup with a BMI < 23.94  kg/m² and aged ≤ 54.5 had the shortest PFS (4.05 months). Patients with an objective response (partial or complete response) to treatment had the longest OS (20.0 months), while patients with a BMI ≤ 26.92 kg/m² and stable or progressive disease as the best response had the shortest OS (11.2 months).

Conclusions

BMI and age may be predictors of PFS in lung SCC patients who receive GP treatment. BMI and best response to GP treatment predicts OS in such patients. Patients’ clinical pathological characteristics may be used to predict the therapeutic efficacy of chemotherapy and survival.

Low Body Mass Index Is an Independent Predictive Factor after Surgical Resection in Patients with Non-Small Cell Lung Cancer

Background:

The effect of body mass index (BMI) on postoperative survival in non-small cell lung cancer (NSCLC) has been controversial. We retrospectively analysed the effect of preoperative BMI on postoperative outcomes of NSCLC surgery.

Methods:

Consecutive 384 NSCLC patients were enrolled. Patients were subdivided into 3 groups: low BMI group (BMI<18.5 kg/m²), normal BMI group (BMI=18.5-24.0 kg/m²) and high BMI group (BMI>24.0 kg/m²). The prognostic significance of BMI was examined retrospectively.

Results:

The 5-year survival of patients with low, normal and high BMI groups were 46.3%, 74.3% and 84.3%, respectively. The low BMI group had a poorer prognosis than the other groups (p<0.001). The survival of high BMI group had a more favorable trend than that of normal BMI group, but this did not reach statistical significance (p=0.057). On multivariate analysis, significant risk factors for cancer-specific survival were male gender (p=0.0061), non-adenocarcinoma histology (p=0.0003), pN1-2 status (p=0.0007), high serum CEA level (p<0.0001) and low BMI (low vs. others: p <0.0001).

Conclusions:

Preoperative BMI is an independent prognostic factor for NSCLC patients after surgical resection, with low BMI patients having an unfavorable prognosis.

Gender differences in the correlation between prognosis and postoperative weight loss in patients with non-small cell lung cancer

OBJECTIVES

The aim of this study was to investigate gender differences in the relationship between preoperative body mass index (BMI), postoperative body weight change and prognosis in patients with non-small cell lung cancer (NSCLC).

METHODS

Two hundred and sixty-three patients with NSCLC were enrolled in this study. Preoperative BMI was categorized based on WHO definition as follows: underweight (BMI <18.5): 21 patients (8.0%), normal (18.5 ≦ BMI <25): 179 patients (68%), overweight and obese (BMI ≧25): 63 patients (24%). Several factors such as age, sex, cancer stage, body weight change and BMI were recorded and correlated to the postoperative overall survival (OS).

RESULTS

For male patients, those in the low-BMI group had the worst prognosis (P < 0.05) whereas female patients with low BMI did not. Male patients with low BMI had statistically significant poorer prognosis compared to corresponding female patients (P < 0.05). Male patients with more than 5% body weight loss within 1 year after operation when compared to preoperative body weight had poorer prognosis than those with less than 5% body weight loss (P < 0.001). Furthermore, these male patients had statistically significant worse prognosis than the corresponding female patients (P < 0.05). In multivariable analysis, gender, more than 5% of body weight loss compared to preoperative body weight, and pathological stage were independent prognostic factors in NSCLC.

CONCLUSIONS

This study illustrates significant gender differences in the relationship between prognosis and BMI or body weight change in patients with postoperative NSCLC.

Clinical Value of Nutritional Status in Cancer: What is its Impact and how it Affects Disease Progression and Prognosis?

Malnutrition is a common finding in cancer patients, which can affect disease progression and survival. This review aims to critically summarize the prognostic role of nutritional status, from Body Mass Index (BMI) and weight loss to nutrition screening tools and biochemical indices, in cancer patients. According to the currently available data, Prognostic Nutritional Index (PNI) was a significant prognostic factor of patients' survival, both in univariate and multivariate analyses. Pre-operative albumin was also correlated with worse outcomes, being an independent prognostic factor of survival in several studies. BMI was also well-studied, with contradictory results. Although, lower BMI was found to be an independent prognostic factor of shorter survival in some studies, in others it did not have an impact on survival. In this aspect, this review highlights the significant prognostic role of nutritional status in the disease progression and survival of cancer patients. Further, good-quality prospective studies are needed in order to draw precise conclusions on the prognostic role of specific nutritional assessment tools, and biochemical indices associated with the nutritional status in more cancer types, such as liver, breast and prostate cancer, and hematological malignancies.

Preoperative Geriatric Nutritional Risk Index: A predictive and prognostic factor in patients with pathological stage I non-small cell lung cancer

BACKGROUND

Surgical outcomes of early-stage non-small cell lung cancer (NSCLC) are poor. The Geriatric Nutritional Risk Index (GNRI) is a useful parameter for evaluating nutritional status. We aimed to investigate if preoperative GNRI could be a predictive factor for pathological stage I NSCLC patients.

PATIENTS AND METHODS

We retrospectively selected 141 consecutive pathological stage I NSCLC patients treated from August 2005 to August 2010. We analyzed their preoperative GNRI in univariate and multivariate Cox regression analyses for postoperative recurrence-free survival (RFS).

RESULTS

A preoperative abnormal GNRI was significantly associated with postoperative recurrence (P = 0.0107). Univariate analyses showed that serum carcinoembryonic antigen (CEA) levels (P = 0.0013), preoperative serum albumin level (P < 0.0001), preoperative GNRI (P = 0.0009), pleural invasion (P < 0.0001) and blood vessel invasion (P = 0.0137) significantly affected RFS. In multivariate analysis, preoperative GNRI (P = 0.0084), CEA level (P = 0.0031), preoperative serum albumin level (P = 0.0041) and pleural invasion (P = 0.0018) were independent prognostic factors. In Kaplan-Meier analysis of RFS, cancer-specific survival (CS), and overall survival (OS) by preoperative GNRI, the abnormal GNRI group had significantly shorter RFS, CS, and OS (5-year RFS, CS, and OS: 52.81% vs. 89.15%; P < 0.0001, 81.73% vs. 94.73%; P = 0.0014 and 50.84% vs. 89.57%; P < 0.0001, log-rank test, respectively).

CONCLUSIONS

Preoperative GNRI is a novel prognostic factor for pathological stage I NSCLC patients, which can identify high-risk patients for postoperative recurrence and cancer-related death.

The Influence of Body Mass Index on Overall Survival Following Surgical Resection of Non-Small Cell Lung Cancer

BACKGROUND

Population studies suggest that high body mass index (BMI) correlates with a reduced risk for death from lung cancer. The aim of our study was to evaluate definitively the influence of BMI on long-term overall survival (OS) in surgical patients with NSCLC.

METHODS

The study population consisted of 1935 patients who underwent surgical resection for lung cancer at M. D. Anderson Cancer Center (2000-2014). Study variables included both patient- and treatment-related characteristics. Univariate and multivariate Cox regression analyses were performed to identify variables associated with OS.

RESULTS

On univariate analysis, significant predictors of improved survival were higher BMI, pathologic tumor stage (stage I versus stage II, III, or IV), type of surgical procedure (lobectomy/pneumonectomy versus wedge resection/segmentectomy), younger age, female sex, and adenocarcinoma histologic subtype (versus squamous) (all p < 0.05). Morbidly obese patients (BMI ≥ 35) demonstrated a trend toward better outcomes than those classified as obese (BMI ≥30 and <35 kg/m²) (p = 0.05), overweight (BMI ≥ 25 and <30 kg/m²) (p = 0.13), or healthy weight (BMI <25 kg/m²) (p = 0.37) (hazard ratio = 0.727, 0.848, 0.926, and 1, respectively). On multivariate analysis, BMI remained an independent predictor of survival (p = 0.02). Propensity matching analysis demonstrated significantly better OS (p = 0.003) in patients with a BMI of 30 kg/m² or higher as compared with a BMI of 25 kg/m².

CONCLUSIONS

In this large, retrospective, single-center series, after control for disease stage and other variables, higher BMI was associated with improved OS after surgical resection of NSCLC. Further studies are necessary to elucidate the precise relationship between BMI and treatment outcomes.

Body mass index and mortality in lung cancer patients: a systematic review and meta-analysis

Studies examining the relation of body mass index (BMI) and mortality in patients with lung cancer have shown diverse results. We conducted a meta-analysis to investigate the association using all available studies from January 1982 to October 2016. PubMed and EMBASE were searched to identify relevant studies. We calculated the summary hazard ratio (HR) and 95% confidence interval (CI) using random effects model. The dose-response relationship was assessed by random effects meta-regression model. Fifty-five articles from 51 studies involving 3 152 552 subjects (males, 54.8%) were included. The pooled results suggested that on average a high BMI decreased risk of death from lung cancer or all-cause. Each 5 kg/m² increase in BMI had a 12% lower risk of lung cancer-specific mortality (HR=0.88, 95% CI: 0.75-1.02, P=0.09) and a 14% lower risk of all-cause mortality (HR=0.86, 95% CI: 0.77-0.96, P<0.01). When stratifying by ethnicity, each 5 kg/m² increase in BMI was associated with 22% and 28% reduction, respectively, in the risk of lung cancer-specific mortality (P<0.01) and all-cause mortality (P<0.01) in Asians, but no association was found in Westerners (P=0.51 and P=0.53, respectively). In conclusion, lung cancer patients with a higher BMI have a longer survival than those with a lower BMI. Considering the significant heterogeneity between included studies, future studies are needed to confirm these findings.

Lung adenocarcinoma may be a more susceptive subtype to a dendritic cell-based cancer vaccine than other subtypes of non-small cell lung cancers: a multicenter retrospective analysis

OBJECTIVE

The J-SICT DC Vaccine Study Group provides dendritic cell (DC) vaccines for compassionate use under unified cell production and patient treatment regimens. We previously reported beneficial effects of DC vaccines on the overall survival of 62 patients with advanced non-small cell lung cancer (NSCLC) in a single-center analysis. Here, we extended analysis to 260 patients with NSCLC who were treated at six centers.

METHODS

Of the 337 patients who met the inclusion criteria, we analyzed 260 patients who received ≥5 peptide-pulsed DC vaccinations once every 2 weeks.

RESULTS

The mean survival time (MST) from diagnosis was 33.0 months (95 % confidence interval [CI]: 27.9-39.2), and that from time of first vaccination was 13.8 months (95 % CI 11.4-16.8). An erythema reaction at the injection site that was ≥30 mm in diameter was correlated most strongly with overall survival from the first vaccine (≥30 vs. < 30 mm: MST 20.4 vs. 8.8 months, P < 0.001). We reported a similar finding in our previous analysis of patients with advanced pancreatic cancer. Interestingly, although such findings were common between patients with adenocarcinoma and those with other subtypes, the former group experienced significantly prolonged overall survival and a higher response rate for erythema (56.3 vs. 37.3 %, respectively, P = 0.014).

CONCLUSIONS

This is the first multicenter study that suggests a possible clinical benefit of DC vaccines for patients with advanced NSCLC, especially those with adenocarcinoma. These findings suggest a specific potential responder population for DC vaccines and warrant further investigation in well-controlled prospective randomized trials.

Association between body mass index and in-hospital outcomes: Analysis of the nationwide inpatient database

IMPORTANCE

Over one-third of American adults (36%) are obese and more than two-thirds (69%) are overweight. The impact of obesity on hospitalization outcomes is not well understood.

OBJECTIVE

To examine the association between body mass index (BMI) and overall, cancer, chronic obstructive pulmonary disease (COPD), asthma, and cardiovascular disease (CVD)-specific in-hospital mortality; postsurgical complications; and hospital length of stay (LOS).

DESIGN

Cross-sectional study.

SETTING

Representative sample of US hospitals included in the Health Cost and Utilization Project Nationwide Inpatient Sample database.

PARTICIPANTS

We obtained data for patients admitted with a primary diagnosis of cancer, COPD, asthma, and CVD.

MAIN OUTCOME

In-hospital mortality, postsurgical complications, and hospital LOS.

RESULTS

A total of 800,417 patients were included in this analysis. A higher proportion of Blacks (26.8%; 12.5%) and Whites (23.3%; 8.7%) had BMI of 40 to 49.9 and ≥50, respectively, compared with Hispanics (20.4%; 7.3%). Compared with normal BMI patients, the odds of in-hospital mortality increased 3.6-fold (odds ratio [OR] 3.62, 95% confidence interval [CI]: 3.37-3.89) for preobese patients, 6.5-fold (OR: 6.52, 95% CI: 5.79-7.34) for patients with BMI: 30 to 31.9, 7.5-fold (OR: 7.57, 95% CI: 6.67-8.59) for patients with BMI: 34 to 35.9, and 1.6- fold (OR: 1.77, 95% CI: 1.56-1.79) for patients with BMI ≥ 50. Compared with normal BMI patients, preobese and overweight patients had shorter hospital stays (β preobese: -1.58, 95% CI: -1.63, -1.52); however, no clear trends were observed for postsurgical complications.

CONCLUSIONS

The majority of hospitalized patients in this analysis had a BMI > 30, and higher BMI was associated with increased risk of mortality and longer hospital stay.

Influence of Body Mass Index on the Prognostic Value of Tumor ¹⁸F-FDG Uptake in Stage I Non-Small Cell Lung Cancer

Background

The impact of host energy balance status on outcome of lung cancer has not been fully explored. It is also unknown if there is a potential modifying effect of body mass index (BMI) on tumor cell behavior in patients with early-stage non-small cell lung cancer (NSCLC). We therefore investigated the interactive effects of tumor [¹⁸F]-fluorodeoxyglucose (FDG) avidity and BMI.

Methods

We investigated 1,197 patients with stage I NSCLC who underwent preoperative FDG positron emission tomography followed by curative resection. The primary outcome measure was disease-free survival (DFS). A multivariable Cox proportional hazards model was used to assess the potential independent effects of the prognostic variables. A stratified Cox regression analysis was also performed to assess the potential modifying effects of BMI on the relationship between tumor FDG uptake and patient survival.

Results

There were 145 tumor recurrences and 19 deaths during a median follow-up of 30 months. Tumor-related variables, including tumor size, maximum standardized uptake value (SUVmax), histologic cell type, differentiation, lymphovascular invasion, and visceral pleural invasion, did not differ significantly according to BMI status. In multivariable Cox regression analysis, overweight or obesity [hazard ratio (HR), 0.59; 95% CI, 0.43–0.81; P = 0.001] and tumor SUVmax (HR, 1.72; 95% CI, 1.43–2.07; P < 0.001) were significantly associated with DFS. There was a significant modifying effect of BMI (P for interaction < 0.001 in multivariable analysis). High tumor SUVmax was more strongly associated with worse DFS in normal weight patients (HR, 4.72; 95% CI, 2.77–8.06; P < 0.001) than in overweight or obese patients (HR, 2.61; 95% CI, 1.58–4.31; P < 0.001).

Conclusions

Tumor FDG avidity is an independent predictor of DFS in patients with early-stage NSCLC and this prognostic value was strengthened in normal weight patients than in overweight or obese patients. These results suggest that the host-tumor interaction between host energy balance status and tumor glucose metabolism plays an important role in the outcome of early-stage NSCLC.

Overweight-mortality paradox and impact of six-minute walk distance in lung transplantation

Overweight–mortality paradox and impact of six-minute walk distance (SMWD) in lung transplantation

[Obesity and lung cancer: incidence and repercussions on epidemiology, pathology and treatments]

INTRODUCTION

Obesity and lung cancer are major public health problems. The purpose of this work is to review the data concerning this association.

METHOD

We report clinical and epidemiological data on obesity and discuss the impact on the incidence of lung cancer, as well as the safety and efficiency of anti-tumor treatments.

RESULTS

Obesity does not contribute to the occurrence of lung cancer, unlike other malignancies. Patients may be more likely to undergo treatment at lower risk. Regarding surgery, obesity makes anaesthesia more difficult, increases the operative duration but does not increase postoperative morbidity and mortality. Chemotherapy and radiotherapy seem to be administered according to the same criteria as patients with normal weight. Paradoxically, survival rates of lung cancer are better in obese patients as well after surgery than after non-surgical treatment.

CONCLUSION

Obesity is related to many neoplasms but not to lung cancer. Regarding long-term survival all treatments combined, it has a favorable effect: this is the "obesity paradox".

Obesity paradox: conditioning on disease enhances biases in estimating the mortality risks of obesity

Supplemental Digital Content is available in the text.

Background:

Many studies have documented an obesity paradox—a survival advantage of being obese—in populations diagnosed with a medical condition. Whether obesity is causally associated with improved mortality in these conditions is unresolved.

Methods:

We develop the logic of collider bias as it pertains to the association between smoking and obesity in a diseased population. Data from the National Health and Nutrition Examination Survey (NHANES) are used to investigate this bias empirically among persons with diabetes and prediabetes (dysglycemia). We also use NHANES to investigate whether reverse causal pathways are more prominent among people with dysglycemia than in the source population. Cox regression analysis is used to examine the extent of the obesity paradox among those with dysglycemia. In the regression analysis, we explore interactions between obesity and smoking, and we implement a variety of data restrictions designed to reduce the extent of reverse causality.

Results:

We find an obesity paradox among persons with dysglycemia. In this population, the inverse association between obesity and smoking is much stronger than in the source population, and the extent of illness and weight loss is greater. The obesity paradox is absent among never-smokers. Among smokers, the paradox is eliminated through successive efforts to reduce the extent of reverse causality.

Conclusion:

Higher mortality among normal-weight people with dysglycemia is not causal but is rather a product of the closer inverse association between obesity and smoking in this subpopulation.