Scientists have taken the first step toward developing a method for detecting certain kinds of cancer simply by analyzing the cells that are shed daily in bodily fluids.
They have shown that with a standard test, they can pick out a few aberrant genes indicative of cancer from among a large number of mostly normal cells.
The finding is expected to lead to a simple new type of cancer test that could find cancers early enough to treat or cure them.
It is the outgrowth of a decade of accumulating progress in understanding the molecular biology of cancer cells.
In a paper being published today in the magazine Science, Dr. Bert Vogelstein of the Johns Hopkins University and his colleagues say they used a technique called molecular diagnostics to look for mutated cancer-causing genes in the body's fluids.
They discovered that bladder cancer, like many other kinds of cancer, features a mutated form of a particular gene, called p53. They looked for and found mutated p53 genes in cells shed naturally in the urine.
The investigators showed that it was possible to screen the nuclear material from all the cells in a urine sample with a standard test for analyzing DNA and to pick out deviant copies of p53.
"I'm excited about this result," said Dr. John Minna, who studies the molecular biology of lung cancer. Dr. Minna, who directs the cancer center at the University of Texas Southwestern Medical Center in Dallas, added that "we would all like to use molecular biology for the early detection of cancer."
In recent years, molecular biologists have begun piecing together a richly detailed picture of how cells gradually change from being healthy to becoming malignant.
At the heart of this transformation is a sequence of molecular blows that disable five or six crucial genes, one after another. As the genes mutate, the cells grow into a benign tumor, then a malignant one, and then spread through the body.
Depending on which genes are found with molecular testing, scientists expect that they will even be able to tell whether a cancer is just getting started or whether it has already spread.