Cancer is as resilient as a cockroach.

That's part of what makes it so difficult to kill. One drug may wipe out 98 percent of a patient's cancer, but the surviving cells can metastasize and mutate in countless ways, becoming resistant to the treatment.

So scientists at Cold Spring Harbor Laboratory are developing a method to track the spectrum of cancer mutations with a simple blood test. Someday, it could allow doctors to prescribe a cocktail of drugs to kill all its variations.

"The idea is you analyze the cancer and find all of its susceptibilities," said James Hicks, who works on the project with fellow Cold Spring Harbor Professor Michael Wigler.

For years, scientists believed cancer was a single disease that caused our own cells to turn against us, frantically multiplying and overwhelming the body. Now they realize the disease comes in countless and ever-changing forms.

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The advance has led doctors away from chemotherapy -- which essentially kills at random -- toward treatments targeting specific gene mutations.

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But those treatments don't always work. They may kill most of the cancer, but the cells with a different genetic pattern can survive. As the patient appears to recover, those remaining cancer cells quietly multiply, mutate and spread.

That explains, in part, why so many cancers strike back with vengeance after doctors beat them into submission.

To solve the problem, scientists are working to develop precision treatments that can be tailored to match the diversity of cancer cells within a particular patient. But first they need to pinpoint all the genetic variations. That's where Hicks and Wigler come in.

After pulling a sample of blood, the scientists use a technique called single-cell sequencing to determine the genetic profile of hundreds of individual cancer cells floating through the body. Essentially, they put each cell into a test tube, crack it open with chemicals, copy the DNA with enzymes and then use a computer to read the patterns.

Scientists have been sequencing whole genomes for more than a decade by piecing together bits of DNA pulled from millions of cells. What makes Hicks and Wigler's work potentially groundbreaking is the idea of profiling single cells, allowing them to see the spectrum of genetic variation in patients with multiple tumors.

The team is working with several companies to apply the technique to prostate, breast, liver and other cancers. The technology is scheduled to be incorporated into a clinical trial slotted for later this year.