Elsevier

Clinica Chimica Acta

Volume 480, May 2018, Pages 41-46
Clinica Chimica Acta

Review
Association between obesity and bladder cancer recurrence: A meta-analysis

https://doi.org/10.1016/j.cca.2018.01.039Get rights and content

Highlights

  • A tight relationship between obesity and bladder cancer prognosis is proposed.

  • Obese patients get higher rate of bladder cancer recurrence compared to patients with normal weight.

  • Obesity is not associated with postoperative survival of bladder cancer.

Abstract

Background

The association between obesity and bladder cancer prognosis is not well-defined. This meta-analysis was performed to explore whether obesity is related to overall survival (OS) and bladder cancer recurrence.

Methods

Relevant English-language studies were identified by searching PubMed® up to November 1, 2017. We pooled the hazard ratios (HR) and 95% confidence intervals (CIs) using a random effect model. Dose-response relationship, subgroup and sensitivity were also analyzed.

Results

Eleven studies were included. Recurrence rate of bladder cancer was significantly greater in obese (HR = 1.76, 95% CI: 1.36–2.28) vs normal weight patients. Stratification analysis showed that females had higher recurrence risk than males (HR = 1.17, 95% CI: 1.05–1.31). Obesity was not significantly associated with bladder cancer OS (HR = 1.21, 95% CI: 0.97–1.52). Dose-response relationship analysis revealed a linear association between BMI and risk of recurrence. Each one kg/m2 increase in BMI was related to a 1.3% increased risk of bladder cancer recurrence (HR = 1.01, 95% CI = 1.01 to 1.02).

Conclusions

This meta-analysis revealed that obesity may be a risk factor for bladder cancer recurrence.

Introduction

Bladder cancer is a common urinary system malignancy with high morbidity and relapse rate. It is the ninth most common and seventh most malignant carcinoma in the world. There are approximately 356,000 new bladder cancer cases and 145,000 bladder cancer deaths annually [1]. Notably, the high incidence of recurrence is a nodus in clinical practice. In accordance with Tumor-Node-Metastasis classification (TNM), tumor grade, and number of primary tumors, 50%–90% of bladder cancer patients will suffer recurrences [2].

Obesity is a public health problem in general and the prevalence of obesity is increasing [3]. As of 2013, the number of overweight and obese individuals reached 2.1 billion worldwide. Of these, the United States accounted for the largest proportion, followed by China and India. Obesity causes a numerous health problems and may impact cancer [4]. In fact, more research has focused on elucidating the relationship between obesity and cancer development. Bhaskaran et al. studied the association between BMI and several cancers and found that high BMI can increase risk of some cancers, like uterine and kidney cancers [5]. Since Kanabrocki et al. first reported the association between obesity and bladder cancer in 1965 [6], numerous studies have tried to identify the effect of obesity on bladder cancer. A meta-analysis by Sun et al. found that obesity increased the risk of bladder cancer and promoted cancer progression [7]. Although several cohort studies have examined the association between obesity and bladder cancer prognosis such as survival and recurrence [[8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18]], results remain largely inconclusive. For example, an epidemiologic study by Kluth et al. found that obesity was an independent risk factor of bladder urothelial carcinoma recurrence. Patients with BMI > 30 kg/m2 had worse outcomes than non-obese individuals [12]. A similar positive association between obesity and increased recurrence rate was also reported by other research teams [9,15,18]. In contrast, a prospective cohort study found that obesity was not an independent risk factor for recurrence [14]. Therefore, we conducted a meta-analysis to summarize the relationship between recurrence, overall survival of bladder cancer and obesity.

Section snippets

Ethical approval

This article did not contain any studies with human participants or animals performed by any of the authors. Ethics approval was not necessary for this study, as this meta-analysis was based on the published data.

Search strategy

Literature was identified by searching PubMed through November 1, 2017. The key words were as follows: ‘obesity’, ‘body mass index’ (‘BMI’), together with ‘bladder cancer’. The references of identified literature were screened for potentially relative articles.

Inclusion criteria

Studies were available

Study characteristics

We identified 387 articles from PubMed prior to November 1, 2017. A total of eleven articles were included in final meta-analysis [[8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18]]. Four studies conducted in North America [8,10,16,17], five in Europe [9,[12], [13], [14],18] and two in Asia [11,15]. A total of 726 patients were recruited in study by Wyszynski et al., and only data from 338 patients were available for BMI analysis [14]. Study by Maurer et al. recruited a total of

Discussion

Postoperative recurrence is a common occurrence during the clinical treatment of bladder cancer, which has aroused wide attention. Our findings revealed that obesity was associated with increased bladder cancer recurrence risk. Subgroup analyses also demonstrated that female patients had higher recurrence risk compared to male individuals.

Treating recurrent cases as new cancers is already a consensus during clinical therapy [26].Bladder cancer is a fairly common and costly malignancy because of

Funding

This study was partly supported by National Natural Science Foundation of China (81473050), Collaborative Innovation Center For Cancer Personalized Medicine, and the Priority Academic Program Development of Jiangsu Higher Education Institutions (Public Health and Preventive Medicine).

Ethical approval

Compliance with ethical standards.

Conflict of interest

The authors declare that they have no conflict of interest.

Informed consent

For this type of study, informed consent does not apply.

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    These authors contribute equally to this work.

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