RCC Epidemiology FactsRCC is more common in the developed, rather than the developing world as the incidence increases with age and other age-related risk factors.
- Countries of Northern America, Europe, Australia and New Zealand have the highest risk of RCC in the world.
- Countries with the lowest-risk of RCC are in Africa and the Caribbean. 
- In the US, there are approximately 64,000 new cases of renal cancer per year and 13,500 people die of renal cancer each year.
- The incidence of renal cancer has steadily risen over the past few decades due to the increased use of axial imaging.
- This corresponds to a steady increase in localized cancers while the rates of locally-advanced and metastatic disease have remained stable. 
- Interestingly, despite the steady increase in the number of cancers, the mortality from kidney cancer has remained stable.
RCC Risk FactorsRCC is more common in men than women. It is the 6th most common cancer in men and the 8th most common cancer in women. The other well-established risk factors that will be discussed in this blog include tobacco exposure and obesity. Putative risk-factors for RCC are listed below and will not be discussed in this blog as there is neither strong evidence in favor of or against each risk. In addition, there are a number of genetic causes of RCC. While these genetic causes are strong predictors of RCC, they are rare and will be the focus of a later blog.
Well-Established Risk Factors for RCCTobacco Exposure
Possible Risk-Factors for RCCHypertension
Chemical Exposures (lead compounds, aromatic hydrocarbons)
Occupational Exposures (asbestos)
Dietary Factors (high fat, low fruit/vegetables)
Tobacco Exposure and Renal Cell Carcinoma
Cigarette smoking is the most well-established risk factor for RCC. It is believed that chronic smoking leads to DNA damage through chronic tissue hypoxia. The risk of RCC is proportional to the dose and duration of exposure. A meta-analysis of 24 studies demonstrated a 38% increased risk of RCC with any smoking exposure; that risk was modified by male sex and more cigarette exposure on a daily basis. This study also demonstrated that smoking cessation alleviates the risk of RCC, but only 10 years after quitting.
|Hunt et al. Int J Cancer, 2005.|
Not only has smoking been attributed to an increased risk of RCC, but smokers also have a higher risk of death from RCC. In fact, it has been demonstrated that for every pack-year of smoking history a patient has a 1% increased risk of death from RCC.
Obesity and Renal Cell CarcinomaRates of RCC increase with increasing Body Mass Index. In 11 studies comparing RCC and BMI, each 5kg/m3 increase in BMI corresponds to a 25% increase in the rate of RCC in men, and 34% increase in women. Obesity leads to an altered endocrine milieu, led by compensatory hyperinsulinemia and production of adipokines, which creates an environment of inflammation and oxidative stress leading to the formation of RCC.
|Renehan et al. Lancet, 2008.|
Contrary to the relationship with smoking, obese patients with RCC have an improved long-term survival after diagnosis. This has been termed the "obesity paradox" and exists in a number of other disease states like patients with chronic kidney disease on dialysis, diabetes and heart failure. Recent evidence indicates that obese patients may present with smaller, earlier-stage and lower grade tumors - indicating for the relative improvement in survival.
- Renal cell carcinoma is more common in the developed world than developing nations.
- The incidence of RCC has increased dramatically in the US - this corresponds to an increased use of axial imaging.
- The number of deaths from RCC has remained stable over the same time period, reflecting the stable rates of advanced and metastatic disease.
- Risk factors for RCC include:
- Male Sex: men are more likely than women to develop RCC
- The risk of RCC increases with increasing exposure to tobacco smoke.
- The risk of death from RCC also increases with tobacco exposure.
- The risk of RCC increases with increasing BMI.
- The risk of death from RCC is lower in patients with a larger BMI (this is termed the "obesity paradox").
This blog was written by Michael Gorin, MD, resident at the Brady Urological Institute at Johns Hopkins. Visit the Brady Urological Website for more information on kidney cancer and its treatment.
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