Kidney Cancer on the Rise Feb. 23, 2011 (Orlando) -- The number of people with kidney cancer in the U.S. has risen steadily since 1975 and, since 1991, the greatest increase has been among younger people, researchers report.

From 1975 to 1990, the number of new cases increased on average by 3.6% annually, says study leader Kenneth G. Nepple, MD, a fellow in urologic oncology at Washington University in St. Louis.

From 1991 to 2006, cases rose on average by 2.9% per year, he says.

Cases increased in all age groups from 1975 to 2006, Nepple tells WebMD. But the proportion of patients diagnosed when they were younger than age 65 increased from 45.9% in 1991 to 55.3% in 2006, he says.

Some of the rise comes from increased detection on CT scans, says Christopher G. Wood, MD, professor of urology at the University of Texas M.D. Anderson Cancer Center in Houston.

"A person comes to the emergency department with a [general] complaint such as belly ache and is given a CT scan. A small kidney cancer that might have gone unnoticed is detected," he tells WebMD.

But that can't explain the trend entirely, because the rise in cases began before use of CT scans started skyrocketing in the 1980s, Wood says.

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