Obesity, hypertension, and the risk of kidney cancer in men.

Background: Obesity and hypertension have been implicated as risk factors f or the development of renal-cell cancer. Methods: We examined the health records of 363,992 Swedish men who underwen t at least one physical examination from 1971 to 1992 and were followed unt il death or the end of 1995. Men with cancer (renal-cell cancer in 759 and renal-pelvis cancer in 136) were identified by cross-linkage of data with t he nationwide Swedish Cancer Registry. Poisson regression analysis was used to estimate relative risks, with adjustments for age, smoking status, body -mass index, and diastolic blood pressure. Results: As compared with men in the lowest three eighths of the cohort for body-mass index, men in the middle three eighths had a 30 to 60 percent gr eater risk of renal-cell cancer, and men in the highest two eighths had nea rly double the risk (P for trend, <0.001). There was also a direct associat ion between higher blood pressures and a higher risk of renal-cell cancer ( P for trend, <0.001 for diastolic pressure; P for trend, 0.007 for systolic pressure). After the first five years of follow-up had been excluded to re duce possible effects of preclinical disease, the risk of renal-cell cancer was still consistently higher in men with a higher body-mass index or high er blood pressure. At the sixth-year follow-up, the risk rose further with increasing blood pressures and decreased with decreasing blood pressures, a fter adjustment for base-line measurements. Men who were current or former smokers had a greater risk of both renal-cell cancer and renal-pelvis cance r than men who were not smokers. There was no relation between body-mass in dex or blood pressure and the risk of renal-pelvis cancer. Conclusions: Higher body-mass index and elevated blood pressure independent ly increase the long-term risk of renal-cell cancer in men. A reduction in blood pressure lowers the risk. (N Engl J Med 2000;343:1305-11.) (C) 2000, Massachusetts Medical Society.