Hopkins researchers develop new technique for detecting cancers

Method scans body fluids for genetic changes in cell components

March 17, 2000|By Jonathan Bor and Michael Dresser | Jonathan Bor and Michael Dresser,SUN STAFF

Researchers at the Johns Hopkins Oncology Center have developed a new way of detecting cancers that requires patients to provide only a urine, saliva or sputum sample.

Dr. David Sidransky said the test would allow doctors to find early cancers that are hard to detect with conventional methods such as biopsies. Labs would screen body fluids for genetic changes that are associated with cancer. The tests would be commercially available within the next five years, he said.

"We now have an entirely new method of cancer detection that can be used when cancers are still amenable to early detection and cure," said Sidransky, a specialist in head and neck cancers.

In a study appearing in today's Science, Sidransky and a team of researchers found that certain cancers could be detected with a high degree of accuracy by scanning body fluids for genetic changes found in mitochondria, the energy producing component of cells. The technique is possible because tumor cells slough off into fluids.

With this method, researchers said they can detect lung cancer in sputum, head and neck cancers in saliva, and bladder cancer in urine. Two years ago, Sidransky reported that he had found a way to screen saliva for cancer by finding mutations in the cell nucleus, but he said the new technique is easier because each cell has multiple copies of mitochondrial DNA.

"Until now, finding cancer-specific mutations in bodily fluids was like looking for a needle in a haystack," he said. "Finding mitochondrial mutations is much easier. With additional research, we expect to be able to identify mitochondrial mutations through a simple blood test."

Mutations were 20 to 200 times more numerous in mitochondrial DNA than in nuclear DNA.

The scientific announcement took a political overtone as Hopkins and Gov. Parris N. Glendening used it to promote the governor's plan to spend $500 million from the national tobacco settlement over the next decade on anti-cancer initiatives.

Glendening praised the Hopkins breakthroughs, saying they are "exactly what we're talking about" in his spending plan. But he warned that "well-intentioned" but "wrong" legislators were trying to divert money he had allocated to cancer to other purposes.

Under the plan, Hopkins and the University of Maryland Medical Center would each receive $15 million a year from the tobacco settlement. The money would be earmarked for cancer research.

"There are people who are saying we should not be using our tobacco settlement money to support great institutions of research," he said. "They're trying to do so many good things an inch deep and make many people feel good."

The governor's warning came as the House Appropriations Committee was putting the final touches on its plan for the tobacco settlement money. The House approach is significantly different from the Senate bill, which the governor supports.

At Hopkins, Sidransky's research is supported by the National Cancer Institute.

Sidransky said a genetically based test for bladder cancer could be available this year, while tests for saliva and lung cancer might be ready within the next four or five years. The technology would be produced by private companies under a licensing agreement with Hopkins.

Glendening also heard Dr. Patrick Walsh, chief of Hopkins urology, discuss an improvement in a blood test that is used widely to screen men for prostate cancer.

The test could be particularly useful for black men who suffer disproportionately from prostate cancer, he said.

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