The theory that viruses are to blame for some forms of human cancer, especially leukemia, was strengthened last week by striking evidence gained from experiments with human volunteers. Most notable: the tests gave reason for increased hope that it may be possible to prevent leukemia with a vaccine.
That viruses cause some forms of mouse leukemia has long been accepted, but years of the most exacting research failed to turn up viruses in human victims of a similar disease, acute leukemia. Probably, reasoned Dr. Steven O. Schwartz of Chicago's Hektoen Institute, this was because...