Urologic Oncology: Seminars and Original Investigations
Original articleBody mass index and the clinicopathological characteristics of clinically localized renal masses—An international retrospective review
Introduction
The incidence of renal masses has been increasing steadily in recent years, at least in part owing to the widespread use of cross-sectional imaging. Interestingly, the prevalence of obesity is on the rise as well as [1] suggesting a potential link between the 2 trends, especially considering that obesity represents a well-established risk factor for renal cell carcinoma (RCC) [2].
A large contemporary study has shown that obesity represents a risk factor for RCC-specific mortality [3]. This finding has been challenged by surgical cohorts showing better cancer-specific survival in patients with obesity [4], [5]. This discrepancy in the literature may be due to different study designs, geographic and socioeconomic factors, or confounding factors that were not previously explored.
Most of the research available has focused on either “kidney cancer” including all subtypes of malignancy groups evaluated as a single entity, or the most frequent histotype of RCC (clear cell) [4]. In reality, a variable proportion (up to 40%) of patients treated for a renal mass harbor benign tumors, and histotypes other than clear cell may represent up to 30% of renal cell malignancies [6]. Furthermore, although the effect of sex, tumor size, and age on localized renal mass pathology has been documented [7] little is known of the association between other RCC pathological characteristics and body mass index (BMI).
In this study, therefore, we perform a detailed analysis of the potential associations between BMI and the clinicopathological features of clinically localized renal masses in a large international cohort.
Section snippets
Cohort
After approval from the institutional review board, we reviewed the records of patients who underwent surgery for a clinically localized renal mass between the years 2000 and 2010 at Duke University Medical Center, Durham NC, USA and S. Orsola-Malpighi Hospital, Bologna, Italy. Only patients who underwent partial nephrectomy, radical nephrectomy, or renal mass enucleation were included in the study. Patients with incomplete data (missing BMI, renal mass pathologic diagnosis, radiological size,
Results
Of the 2,235 available records, 1,748 met the criteria and were reviewed after institutional review board approval. Of those 1,117 (64%) underwent surgery at Duke University Medical Center and 631 (36%) were treated at S. Orsola-Malpighi Hospital. Radical nephrectomies constituted 57% of cases, whereas partial nephrectomies were performed in 43% of patients. Patient and renal mass characteristics are detailed in Table 1. Most patients were males (64%) and the median age was 62 years (52–70).
Discussion
With the adoption and use of advanced abdominal imaging, an increase in the incidence of renal masses has been identified in recent years. Interestingly, there has also been a rise in obesity, which is a well-known risk factor for RCC [9], [10], [11]. However, data on the correlation of BMI with the characteristics of renal masses remain controversial. We examined whether there is an association between BMI and the clinicopathological characteristics of localized renal masses including renal
Conclusion
Our study found that higher BMI was associated with low Fuhrman grade in clinically localized renal masses, whereas no association was demonstrated between BMI and tumor size, renal mass pathology, RCC subtype, or clinical stage. Additional studies are needed to clarify the causal agent for the purportedly improved survivorship and lesser aggressive nature of RCC in overweight and patients with obesity.
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