FALSE HOPE ON BREAST CANCER?

Craig Malbon and his colleagues were convinced that they had made a momentous discovery. So they held a press conference at New York City's Grand Hyatt Hotel to announce it. What they had found, Malbon told reporters last week, was an enzyme that acts as the master switch for breast cancer, a disease that kills 44,000 women in the U.S. each year. "This gives us a new diagnostic tool and a new therapeutic strategy," maintained Malbon, a pharmacologist at the State University of New York at Stony Brook.

Or does it? What the SUNY team found was that some breast-cancer cells contain elevated levels of enzymes known as mitogen-activated protein kinases. The problem is, MAP kinases are elevated in many dividing cells. Finding high levels in breast tumors, as Princeton University molecular biologist Arnold Levine dryly observes, hardly comes as a surprise.

Beyond that, the SUNY study, which is described in the April issue of the Journal of Clinical Investigation, is very small. Malbon and his team measured enzyme abundance in the breast cells of just 30 women, 11 of whom had undergone surgery to remove suspicious tumors. Cells taken from the tumors, later shown to be cancerous, contained MAP-kinase levels 5 to 20 times as high as those in normal breast cells. But other researchers argue that you would have to examine a lot more patients before drawing any firm conclusions.

Even if that's true, say other scientists, MAP kinases are just one component of an elaborate biochemical network that controls the process of cell division. Though breast tumors may contain high levels of the enzymes, that may well be an effect of malignancy rather than the cause. This does not mean that MAP kinases are not important contributors to tumor growth. But, cautions Susan Braun, president of the Susan G. Komen Breast Cancer Foundation in Texas, "people should understand that this is a piece of the puzzle, not the single answer." Indeed, there will probably never be a single answer to breast cancer, a disease as variable as it is complex.

--By J. Madeleine Nash. With reporting by Alice Park/New York