Melanoma researchers have identified protein markers that help predict whether an abnormal mole could become cancerous, which could lead to strategies to prevent the deadly disease.

The same molecular signalling systems that are turned on in melanomas are also switched on in atypical moles, explained principal investigator Dr. John Kirkwood, director of the University of Pittsburgh Cancer Institute's melanoma center.

His colleague Dr. Wenjun Wang presented the findings yesterday in Washington, D.C., at the annual meeting of the American Association for Cancer Research.

In the study, 40 patients who had previous diagnosis of melanoma and at least four atypical moles were treated with either high- or low-dose interferon. A mole is considered atypical if it is assymetrical, has an irregular border, has variations in its color or is unusually large, Dr. Kirkwood said.

Two moles were removed immediately. Then, the participant received either high- or low-dose interferon therapy for three months, and two more moles were excised.

The researchers found that the more abnormal the mole, the higher its level of a protein called STAT3.

Also, "we now know that STAT3 is turned off by interferon," Dr. Kirkwood said. "The interferon effects with low doses [were] not as great as the influence at high doses."

High-dose interferon reduced STAT3 levels by 55 percent, while low doses reduced the level by 39 percent. Conversely, an anti-tumor marker called STAT1 was nearly eight times greater after high-dose therapy and was 1.4 times greater with low doses.

About 7 percent of the population has atypical moles, so it would not be appropriate to treat all of them with interferon to prevent melanoma, he said. But the therapy might prevent new disease in high-risk individuals who have had melanoma and many abnormal moles.

It's also possible that suspicious lesions could be tested beyond a microscopic exam of their cells to determine how dangerous they are. More research is needed to establish the usefulness of the markers.

"We now don't need to look just at the pathology," Dr. Kirkwood said. "We might look at the STAT3 level in a mole and say, 'This is a bad actor.'"

The researchers are conducting more studies to assess how long the interferon effects last and how new melanomas develop in treated patients.

For more information about the research projects, call UPMC's cancer information and referral service at 412-647-2811.