- NEW YORK (Reuters Health) - Better detection methods, such as increased
use of ultrasound and CT scans, explain part but not all of the continuing,
rapid rise in the number of new cases of kidney cancer diagnosed in the
US, and in the increasing death rate from the cancer, researchers report.
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- The increases in new cases and in deaths
from kidney cancer ''have been greater among blacks than whites, providing
clues for further research,'' write Dr. Wong-Ho Chow and colleagues at
the National Cancer Institute in Bethesda, Maryland. Their report is published
in the May 5th issue of The Journal of the American Medical Association.
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- The research team sought to determine
if improved early detection was behind a reported rise in kidney cancer
incidence. They used National Cancer Institute data to track US rates for
kidney cancer in nine geographic areas between 1975 to 1995. These areas
represent about 10% of the US population.
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- They found that rates for these malignancies
"increased steadily'' during this time period, "by 2.3% annually
among white men, 3.1% among white women, 3.9% among black men, and 4.3%
among black women.''
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- Most of the increase occurred in smaller,
localized tumors " malignancies that are often asymptomatic and only
detected through the use of high-tech screening technologies.
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- However, "upward trends (in incidence)
were also apparent for more advanced... tumors,'' according to Chow and
colleagues, and "kidney cancer (death) rates increased in all race
and sex groups.'' Both of these findings suggest that the observed rise
in kidney cancer incidence might be linked to more than just improvements
in early detection, they conclude.
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- The investigators point out that US rates
for smoking " a risk factor for kidney cancer " have actually
declined since the 1970s. They speculate, however, that "given the
long latency of tumor development... smoking prevalence in earlier decades
might have contributed to continuing increases in renal cell cancer, particularly
at older ages.''
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- The reasons behind the higher incidence
of kidney cancer among blacks versus whites are also unclear. On this point,
the researchers suggest that obesity and hypertension, established risk
factors for renal cell cancer, may play a role. Both of these risk factors
"are more prevalent among blacks than whites in the United States.''
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- More than 30,000 new cases of kidney
cancer are diagnosed annually in the US, and 12,000 Americans die from
the disease each year.
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- SOURCE: The Journal of the American Medical
Association 1999;281:1628-1631.
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