Kidney cancer (renal-cell carcinoma) is among the most rapidly increasing cancers in the U.S., particularly among those with ancestral roots in Africa.1 Past studies have found an association between renal-cell carcinoma and cigarette smoking, obesity, the use of certain pain-killing medications, diuretics and high blood pressure.

A recent long-term prospective study of 363,992 Swedish men sheds some light on the most important risk factors for renal-cell carcinoma.2 The men in this study were on average 44 years old at the start of the study and they were followed for an average of 16 years. Cigarette smoking was associated with a 60% increased risk of developing renal-cell carcinoma. By contrast the risk was increased much more by both an increased body weight and an increase in blood pressure. For men less than 50 years at entry the risk of developing renal-cell carcinoma was nearly doubled for those who had a body mass index (BMI) of 22.86 to 25.96 compared to the thinnest men (BMI < 22.85). For men with a BMI of 26 or more the risk was increased 2.5 fold.The impact of increasing blood pressure (BP) on the risk of renal-cell carcinoma in this study was even greater than that of cigarette smoking or excessive body weight. For men under age 50 years, a diastolic BP of 80-99mmHg was associated with a 2.2-fold increased risk compared to those with a diastolic BP less than 80. For those with a diastolic BP of 100mmHg or more the risk increased 4.5-fold. It is possible that cancer of the kidney could be causing some elevation of BP. However, even after excluding those men who developed this cancer within five years of follow-up, the risk was still much greater for those with higher BP.Precisely how weight gain and increasing BP promote renal-cell carcinoma is not yet known but it seems clear that the primary reason this deadly cancer is increasing in the U.S. is the increasing number of overweight people coupled with a high incidence of hypertension. The authors of this study concluded, “Our findings underscore the importance of even small excesses of body-mass index and BP in the development of renal-cell cancer and suggest that effective control of weight and hypertension may be useful in the prevention of this increasingly common type of cancer.” 1. Chow WH, Devesa SS, Warren JL, Fraumeni JF Jr. JAMA 1999;281: 1628-312. Chow WH, Gridley G, Fraumeni JF, Jarvholm B. N Engl J Med 2000;343:1305-11