HACKENSACK, N.J. – When repeated chemotherapy and radiation treatments failed to stop the cancerous tumors from growing in their 9-year-old son's lungs and chest, a Ridgewood, N.J., couple took a desperate chance — on a bunch of mice.

They paid a laboratory $25,000 to inject pieces of their son's tumors into the rodents and then test different drugs on the mice. The lab offered no guarantees, but the hope was to find a treatment that would shrink the boy's particular tumors and possibly cure him of Ewing's sarcoma.

Months passed as the tumors grew in the mice and standard treatments failed on Michael Feeney. Then the lab discovered a three-drug cocktail that began to heal the mice, destroying the cancer cells.

And now, Michael's tumors are also shrinking thanks to those drugs.

"If someone had asked me what the chances were of this working, I would have said one or less than one in 10," said Dr. Leonard Wexler, who is Michael's doctor and a pediatric oncologist from Memorial Sloan-Kettering Cancer Center in New York. "But I am delighted, joyful, and just praying with his family that it will be a long recovery."

Michael's treatment may seem unorthodox but, increasingly, researchers believe the key to effectively fighting cancer is by tailoring treatment to the genetic makeup of a patient. By growing the human tumors in mice, researchers can test different treatments on the rodents.

Though most of the research on these treatments is done at academic institutions, the Feeney family used one of the few companies that will work with the general public, taking tumors from patients who are not in a clinical trial. The lab they used, Champions Oncology, has a corporate office in Hackensack. Treatments are tested on mice at Johns Hopkins, said Dr. Ronnie Morris, an internist and ­president of Champions.

"Normally, the way cancer is treated is by trial and error," Morris said. "With this, we have the ability, for the first time, to test 10 different drugs on any patient's tumor at the same time."

That process was a relief to Michael's mother, Jill Feeney. "The great thing about this is Michael didn't have to be a guinea pig with all the drugs."

The medicines that Michael is taking are all approved for treating cancer, so insurance covers those costs. But the fees for the mice trials are not covered.

Those fees are decreasing, however, as scientists refine the process, and are now down to about $10,000 per patient, said Dr. David Sidransky, one of the founders of Champions.

Jill Feeney said her family was fortunate that it could pay the lab, but believes insurance companies could ultimately save money by not having to cover a drug that is ineffective.

"We figured we didn't have anything to lose but our rainy-day fund — and it was pouring," Feeney said. "But people who can't afford this shouldn't be excluded because of money."

Michael has been battling cancer since he was 6. Diagnosed with Ewing's sarcoma, a very rare, aggressive and often fatal bone cancer that typically develops in children and young adults, Michael has managed to maintain a somewhat normal life while undergoing a slew of medical procedures, including surgery to replace his shoulder blade.

In the fall of 2009, he was complaining of pain in his shoulder. By December, doctors not only found that a tumor was causing the pain but also that there were nodules in his lungs.

Michael began treatment immediately and has had precious few spells without some type of surgery, chemo or radiation. Though he has lost his hair several times, he has maintained his weight and otherwise looks healthy. He was home-schooled for only a short time and does well academically in his fourth-grade class.