Cancer is a stealthy killer, a deadly villain with many guises.
Tumors can invade tissues without alerting the soldiers of the immune system to come out and fight. Clinical trials employing the new technique in human cancer patients began in 2000. On another front, molecular and cell biologist Kathleen Collins has succeeded in purifying new components of human telomerase, an enzyme that promotes unlimited cell growth. The enzyme first switches on in the fetus, then turns off shortly after birth. In adults, it plays a part in certain cells needing constant replacement, including skin and blood cells.