Urine Test May Find Early Kidney Cancer

Looks for changes in tumor suppressor genes

MONDAY, Dec. 15, 2003 (HealthDayNews) -- Researchers are reporting what could be the first test for early detection of kidney cancer, a potential lifesaver for tens of thousands of patients.

Nearly 32,000 Americans will be diagnosed with kidney cancer this year, making it the eighth most common malignancy, and an estimated 11,900 will die of it. Detected early, kidney cancer is potentially curable -- usually by surgery to remove the affected kidney -- but the prognosis for advanced stages of the disease is poor.

Most cases of kidney cancer now are diagnosed by imaging techniques such as ultrasound or CT scans, which look for an abnormal growth, followed by a biopsy to detect cancer cells in a tissue sample. Generally, this means the diagnosis is made only after surgery.

But researchers at Fox Chase Cancer Center in Philadelphia say a urine test has found genetic patterns that signal the disease in patients with early stages of the disease.

The test looks for signs of methylation, a process that inactivates genes that work to suppress cancer, explains Paul Cairns, director of the Molecular Detection of Cancer Laboratory at Fox Chase and lead author of a report on the study in the Dec. 15 issue of Cancer Research.

Methylated genes were found in all of 50 urine samples from patients with early-stage kidney tumors, most of them cancerous, the report says. No such altered genes were found in urine samples from healthy individuals or patients with other kidney diseases.

Cairns says his group is planning "to extend the study to larger numbers, to see if we can detect methylation in precancerous lesions. It would be nice to get hold of what we call candidate precancerous lesions," cells that are on the verge of becoming cancerous.

Such a study will include people who are at high risk because of a family history of kidney cancer, Cairns says. "Before you propose a test on the general population, you go to people with a known heritable mutation," he explains.

While the sort of test used in the study is relatively new, "the technology is now a lot more widespread in laboratories around the world," Cairns says. If all goes well in the inevitable long series of studies that lie ahead, he says, the test could become part of routine screening.

"You can use the same technology to detect bladder and prostate cancer," Cairns says. "If you could screen for several cancers at once, that would make its use practical."

The technology used in the test is formally called methylation-specific polymerase chain reaction. It searches for changes in six specific tumor-suppressor genes that prevent normal kidney cells from the uncontrolled growth that is cancer.

The test could be used to screen for several cancers in a single urine sample because similar changes are found in tumor-suppressor genes for those cancers, Cairns says.

The study is "a good start, but very preliminary," says Dr. Ronald M. Bukowski, director of the Cleveland Clinic Taussig Cancer Center and director of the Kidney Cancer Foundation medical advisory board.

"One thing that should be noted is that three of the patients they studied had benign kidney tumors, not cancers," Bukowski says. The test might thus detect growths that do not require the drastic measures needed for cancer, he adds.

"They need to study more patients with other cancers and they also have to expand the number of people they study," he says. "The development of a urinary or blood test for early detection is obviously very desirable."

More information

An overview of kidney cancer can be found at the National Cancer Institute or the American Cancer Society.

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