Results from two large cohorts indicated that increasing blood pressure levels were associated with an increased risk for developing kidney cancer among both men and women. The data were taken from more than 150,000 participants in the Women’s Health Initiative (WHI) and more than 350,000 men in the Multiple Risk Factor Intervention Trial (MRFIT).
“Additional prospective studies are needed to determine whether treatment and control of hypertension can reduce the risk of kidney cancer and if so, whether specific drug therapies would differ in preventive efficacy,” Kristen M. Sanfilippo, MD, of the department of hematology at Washington University, St. Louis, and colleagues wrote in Hypertension.
In the participants in the WHI, followed for a median of 15 years, 407 incident kidney cancers were diagnosed. Data indicated that the incidence of kidney cancer significantly increased with increasing systolic and diastolic blood pressure, previous hypertension diagnosis or treatment, and higher body mass index and waist circumference categories.
Specifically, the researchers found that women with a systolic blood pressure between 120.1 to 130 mm Hg had a 33% increased kidney cancer incidence compared with women with a systolic pressure of 120 mm Hg or less (HR = 1.33; 95% CI, 1.01-1.75). In addition, a diastolic blood pressure of 90 mm Hg or greater was also independently associated with kidney cancer (HR = 1.56; 95% CI, 1.06-2.29).
When the researchers stratified the patients by BMI and adjusted for age, smoking, and race/ethnicity, they found that kidney cancer risk associated with elevated systolic blood pressure was found within each strata of BMI. However, the link was only consistently significant for women with a BMI of 30 or greater. Similarly, women with the highest waist circumferences (> 97.9 cm) had almost twice the risk for kidney cancer (HR = 1.91; 95% CI, 1.38-2.63).
Men in the MRFIT study were followed for 25 years, during which 906 deaths from kidney cancer occurred. Data indicated that men who died of kidney cancer had a greater systolic blood pressure at study entry compared with those who did not die.
The risk for dying from kidney cancer increased with increasing blood pressure levels even among patients with levels considered to be normal. Men with a systolic blood pressure of less than 120 mm Hg had about a 29% increased risk for dying from kidney cancer; whereas, men with a systolic pressure greater than 160 mm Hg had an 87% increased risk for kidney cancer death. The link between baseline diastolic blood pressure and kidney cancer mortality was not as strong.
The researchers also found an increased risk for kidney cancer death among cigarette smokers (HR = 1.75; 95% CI, 1.53-2.00; P = .0001). Among those who died from the disease, 45.5% reported smoking cigarettes at study entry. As expected, the risk for kidney cancer death was lowest among nonsmokers with a systolic blood pressure of less than 120 mm Hg.