In the 25 years since then-President Richard Nixon declared the “War on Cancer,” researchers have learned a great deal about the enemy. In particular, they have uncovered a host of genetic blunders that can drive cells to become cancerous and grow out of control. They have learned that the balance of power shifts within many cancer cells, as genes called oncogenes, whose protein products foster cell growth, become overactive, while so-called tumor-suppressor genes, whose products normally act to keep cell growth in check, are disabled. So far, these intelligence efforts have yet to accomplish the war's objectives: better treatments that can vanquish this dread disease. But that could be changing