Screening Technique Helps Spot Bladder Cancer Early

Urine test relies on cancer-linked protein marker

TUESDAY, Feb. 15, 2005 (HealthDay News) -- A relatively quick, cheap new urine test beats standard urine screening at spotting bladder cancer early, researchers report.

That's important, since one in every four cases of bladder cancer is detected after it's already spread to other sites. Any screening tool that could help spot tumors sooner might help save thousands of lives a year, experts say.

The new test, which looks for high levels of a protein linked to cancer cells, "is better than what's generally considered the standard urine test" for bladder cancer, concluded lead researcher Dr. H. Barton Grossman, of M.D. Anderson Cancer Center, in Houston.

What's more, Grossman said, the new test "also picked up some cancers that weren't detected initially by cystoscopy," an invasive procedure where doctors view the bladder using a tiny camera inserted via the urethra.

Ideally, he said, a combination of cystoscopy and the protein-based urine test may become the new gold standard for bladder cancer detection.

The findings appear in the Feb. 16 issue of the Journal of the American Medical Association, alongside another study that finds certain genetic tests can help improve the care of colon cancer patients. Also this week, two studies in the Feb. 15 issue of Cancer Research suggest that drugs that block estrogen may help fight lung cancer.

In the bladder cancer study, Grossman and his team compared the accuracy of two urine tests in diagnosing bladder cancer in more than 1,300 patients considered to be at high risk for the disease because of factors such as a long history of smoking, the presence of blood in urine, or problems with urination.

One test, called urine cytology, has long been used by urologists and involves the examination, in the laboratory, of cells voided in urine. The newer test looks for traces of NMP22, a protein produced in higher concentrations by malignant cells. All of the patients also underwent cystoscopy.

The NMP22/cystoscopy combination beat urine cytology/cystoscopy at spotting bladder cancers (as confirmed on biopsy), Grossman's team reported. Bladder cancer was diagnosed in 79 of the patients, with the protein test turning up positive in nearly 56 percent of those cases, compared with about 16 percent for the older test. The protein-based urine test also spotted four cases of bladder cancer that were missed on cystoscopy.

The new test did have a slightly lower specificity than the older urine test, meaning that the older test was still better at avoiding false-positive results.

"On the basis of this study, this new test is more sensitive than [urine] cytology," said Carolyn Bruzdzinski, scientific program director for the American Cancer Society. "About 25 percent of bladder cancers are detected at the point where they are already invasive or metastatic -- that's a significant number, so if we can improve early detection, that's key."

The protein-based test has one other advantage: because it relies on a simple protein marker, urine samples do not have to be sent to a lab for investigation, cutting down on both time and health-care costs.

Grossman and Bruzdzinski agreed that, because it is prone to false-positives, the new urine test should be used only in conjunction with cystoscopy, and only among high-risk groups.

"The NMP22 test has been available for a couple years, but it's only recently received specific FDA approval for screening," Grossman noted. "Hopefully it will be used earlier, and more patients will be tested sooner." According to ACS statistics, bladder cancer remains the fifth leading cancer killer in the United States, claiming 13,000 lives each year.

In another study in the same issue of the journal, researchers at the Cleveland Clinic found a new method of genetic screening, called conversion analysis, is more accurate at spotting distinct mutations behind various forms of colon cancer.

Besides helping doctors tailor treatment for individual patients, more accurate genetic profiling of individuals' cancers could "prompt genetic counseling, screening and surveillance" of family members thought to be at higher risk for these malignancies, the researchers wrote.

Two more studies, both from the University of Pittsburgh and both published in Cancer Research, suggest lung cancer is sensitive to the activity of circulating estrogen.

In one study of mice grafted with human lung cancer tumors, researchers found that tumors shrank when the mice received a breast cancer drug designed to block cellular estrogen receptors. And in a second study, estrogen was seen to spur the activity of genes linked to the growth of lung cancer, in much the same way it activates breast cancer genes.

In a prepared statement, Jill Siegfried, of the university's Cancer Institute, said "our studies continue to show that lung cancer cells grow in response to estrogen and that stopping or slowing the spread of the disease may be dependent on blocking the action of estrogen."

More information

To find out more about bladder cancer, and other malignancies, head to the American Cancer Society.

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