“With increased early detection and treatment of small tumours, we would expect to see a decrease in mortality associated with kidney cancer,” says senior author Brent K. Hollenbeck, M.D., assistant professor of urology at the University of Michigan Medical School. “Surprisingly, that’s not what we found. Our research shows that an increase in detection and treatment is not leading to a reduction in the kidney cancer mortality rate.”
The researchers examined data from 34,503 patients with kidney cancer. Over the study period (1983 to 2002), researchers observed a rise in the occurrence of kidney cancer for tumours of all sizes. But the greatest increases in kidney cancer incidence were among tumours four centimetres or smaller. Tumours of this size, often found in patients without any clinical signs or symptoms, are being detected more and more with the widespread use of abdominal imaging studies, such as Magnetic Resonance Imaging. These small kidney tumours are considered curable by surgery, which has led to a rise in surgery for kidney cancer.
Even as early detection and surgical treatment increased, however, mortality rates caused by kidney cancer during the time period rose dramatically, from 1.2 to 3.2 deaths per 100,000 people in the United States.
These seemingly contradictory findings can be explained, in part, through the rising incidence of larger, more lethal tumours, says lead author John M. Hollingsworth, M.D. “While more and more small, detectable kidney tumours are being treated, the absolute number of patients with larger, lethal masses has not decreased. And it is these larger, lethal masses that seem to mainly affect mortality.”
The researchers say the data also suggest something else: A proportion of these smaller, incidentally found kidney tumours may not merit surgical removal.
MEDICA.de; Source: University of Michigan Health System