U. S. clinicians perform more than 50 million Pap smears each year to screen women for cervical cancer. But the test, which involves microscopically examining cells from the cervix, misses a notoriously high proportion (estimates range up to 40 percent) of abnormalities. Cambridge University researchers have devised a new screening tool that they hope will cut down on these missed opportunities to catch cancer while it’s still curable.

The tool is a stain that selectively marks proliferating-thus potentially cancerous-cervical cells, making them readily visible among their nondividing normal counterparts. In small preliminary tests, the new stain helped researchers catch cervical abnormalities with 100 percent efficiency. The Cancer Research Campaign, the British charity that funded the research, has licensed the stain to Santa Clara, Calif.-based diaDexus. The company expects to have it on the market “within a couple of years.”