The evidence that L-asparaginase seems effective against only some forms of leukemia again emphasizes the fact that "cancer" is not just one disease but many. The search for a "cure," therefore, is a search for many cures; researchers must pursue clues in every conceivable direction. Last week's news of the pursuit involved viruses—plus additional confirmation that oral contraceptive pills have not only been acquitted of causing cancer but actually help prevent one form in certain cases.
Viruses have long been known to produce cancers in animals, and are suspected of doing the same...