US Kidney Cancer
Cases And Deaths Rising Fast
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.
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.
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.
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.''
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.
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.
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.''
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.''
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.
SOURCE: The Journal of the American Medical Association 1999;281:1628-1631.