Renal cell carcinoma (RCC) accounts for the vast majority of renal tumors. There is substantial variation in RCC incidence worldwide, which may reflect underlying geographic heterogeneity in the prevalence of underlying RCC risk factors. Prior study has established higher rates of RCC incidence in developed countries which generally have more modifiable risk factors, such as obesity and diabetes. However, the degree to which modifiable risk factors explain the interstate variation in renal tumor incidence within the United States is unknown. We quantify this relationship by associating longitudinal variations in the prevalence of obesity, diabetes, smoking, and alcohol consumption across states with renal tumor incidence from 2001 to 2016.
Statewide age-adjusted incidence rates of renal parenchymal tumors (excluding those of the renal pelvis) per 100,000 adults were obtained from the North American Association of Central Cancer Registries from 2001–2016. This registry contains incidence data covering 93% of the United States population. Survey-weighted state-wide annual prevalence estimates for modifiable RCC risk factors (obesity, smoking, diabetes, and alcohol consumption) for adults were extracted from the Behavioral Risk Factor Surveillance System from 2001 onwards. All states besides Kansas had sufficient data for analysis. Data for renal tumor incidence and modifiable risk factor prevalence was collated as a multi-panel time series by state. Scatter plots were generated to evaluate univariable associations between risk factors and renal tumor incidence. Significant univariable associations were verified using random-effects linear regression with random effects at the state level, which related changes in modifiable risk factor prevalence to renal tumor incidence both within and between states over time.
Both renal tumor incidence (Figure 1A)and obesity prevalence (Figure 1B) are increasing in the United States with substantial variation between states in both. Obesity and diabetes prevalence were significantly associated with renal parenchymal tumor incidence (Figure 2), whereas smoking or alcohol consumption were not. Random effects linear regression modelling with obesity and diabetes on renal tumor incidence was performed. Regression coefficients indicated the increased age-adjusted renal tumor incidence (per 100,000 people) was related to the increased prevalence of the following modifiable risk factors: BMI 30-35 (24.4, p<0.001), BMI 35-40 (41.4, p<0.001), BMI 40+ (72.2, p<0.001), diabetes (8.4, p=0.291). Although there was significant collinearity between obesity and diabetes prevalence, the model demonstrated that obesity remained significantly associated with renal tumor incidence while diabetes was no longer significant. In fact, obesity alone explained 52% of variation in renal tumor incidence within states over time and 62% of variation between states.
The incidence of renal tumors has increased substantially from 2001 to 2016 in the United States. Although diabetes was significantly associated with renal tumor incidence on univariable analysis, it did not remain significant after adjusting for obesity. Smoking and alcohol consumption were not significantly related to renal tumor incidence. However, variation in obesity prevalence explained significant variation in renal tumor incidence seen between states and within states over time, such that states with higher baseline obesity prevalence tended to have higher renal tumor incidence and states with larger increases in obesity prevalence had larger increases in renal tumor incidence. This strengthens the epidemiologic evidence linking obesity to renal tumor. Further study is warranted to determine if initiatives combatting obesity can reduce renal tumor incidence.
OBESITY EXPLAINS SIGNIFICANT STATEWIDE VARIATION IN RENAL PARENCHYMAL TUMOR INCIDENCE IN THE UNITED STATES
Category
Health Services
Description
Presented By: Abhishek Venkataramana
Authors: Abhishek Venkataramana
Vidit Sharma
Leslie Ojeaburu
W. Scott Comulada
Mark S. Litwin
Christopher S. Saigal