Frankincense, valued for thousands of years as a liniment, perfume and biblical gift, may have a new use: cancer treatment.

A recent study at the Virginia-Maryland College of Veterinary Medicine at Virginia Polytechnic Institute found frankincense to be effective against skin cancer in horses, said John Robertson, director of the college's Center for Comparative Oncology. Robertson, who led the study, said the results may offer a new alternative to fight skin cancer in humans as well.

"(Frankincense) has been used as a wound treatment for a long time," Robertson said. "It's interesting that it has useful properties for us."

The study involved six horses from New Jersey, Pennsylvania, Virginia and Maryland suffering from malignant melanoma, a fatal form of skin cancer. During a two-week period, researchers injected tumors in one group of horses with frankincense oil and applied a topical treatment of the oil to the others.

At the end of the trial period, the tumors treated with frankincense were measured and compared to tumors left untreated, and the cells were biopsied, Robertson said. The verdict was clear: Frankincense, both injected and topical treatments, had reduced tumor growth in all six horses and killed some cancer cells.

"We've found that over a two-week period, the treated melanomas have broken down during a period of degeneration," Robertson said.

Malignant melanoma is similar in both humans and horses. Horses with pale coats of gray to white are most vulnerable, he said. In humans, melanoma tends to be correlated with pale complexions, sun exposure and age. The American Cancer Society estimates on its Web site, www.cancer.org, that about 60,000 people were diagnosed with melanoma in 2005 and nearly 8,000 people died from it.

It is simply too early to tell if frankincense would kill cancer cells in humans, Robertson said. But the horses' reactions offered promise.

"It would be difficult to say if anything will come out of this for humans, but we'll continue to work with horses and see what results we get."

The study did not demonstrate frankincense to be a proven elixir for melanoma, Robertson cautioned.

"In no way have we cured the animals, but we have seen a significant enough effect to continue the trials," he said.

If further studies confirm frankincense's potency, Maryland horse owners would certainly give it a try, said Tracy McKenna, horse owner and editor of The Equiery, a monthly horse magazine based in Lisbon.

"Horse owners tend to be very open to alternative forms of medicine," McKenna said. "They are very much in tune with their horses. They're not afraid to try things like acupuncture or a chiropractor. If it makes their horses feel better, they're into it."

Melanoma is like the "common cold" among gray horses -- so common that some owners forget about it until it becomes untreatable, McKenna said. One of her colleagues worked with a horse that lived for eight years with melanoma.

"You forget that once it's there, it's there," McKenna said. "There are people who never go out and buy a gray horse because they don't want to deal with it."

Researchers are unsure exactly why frankincense is effective against melanoma. Robertson said it is likely that a chemical component of frankincense kills cancer cells. Frankincense oil, a resin derived from the Boswellia tree, contains hundreds of compounds. One of these compounds, boswellic acid, is known to have anti-tumor properties, Robertson said.

For the past decade, researchers have developed and tested therapies at the college, which might be the only place in the country that studies equine melanoma, Robertson said. New gene and molecule technology have enabled marked progress in the last two years.

Despite these advances, scientists know far less about melanoma in horses than in humans, Robertson said. For example, it is known that untreated melanoma in humans can eventually spread to the brain. Whether cancer can take such a route in horses has probably not been examined, he said.

But studies such as this show how far the field has come, he said. When Robertson entered the field of equine medicine 30 years ago, people generally assumed that horse lesions were benign moles. Researchers were stunned when they eventually found the tumors to be malignant.

Robertson plans to extend the study by treating 12-18 new horses during the next six months.

"We are very interested in talking with people whose horses are affected, and making progress against the disease," he said. "It's surprised me that we've had the response we've had, but there are many horse owners out there who are devoted to their horses."

The Capital News Service contributed to this report.