Viruses & Cancer
Though viruses have been known for 50 years to cause some animal cancers, only in the last few years has it become medically respectable to suggest such a link in human forms of this deadly family of diseases. Search for the link was intensified after Drs. Sarah E. Stewart and Bernice E. Eddy of the National Institutes of Health showed the potency and versatility of a mouse cancer virus (TIME, July 27).
Startling Results. Dr. Grace, now 36. was a fast-rising surgeon in Nashville, Tenn. in 1955, when his two-year-old son died of leukemia. Dr. Grace gave up his surgical practice, moved to Buffalo's Roswell Park Memorial Institute. As senior research surgeon, he began tracking down virus clues to cancer. Early reports on the Stewart-Eddy polyoma virus gave him a strong lead. So did studies by Chicago's Dr. Steven O. Schwartz, who induced leukemia in mice with material from human patients. But Dr. Schwartz's work was confined to leukemia victims. Dr. Grace reached out to cover 20 different kinds of human cancer—acute and chronic leukemia, malignant melanoma, carcinoma in the breast, colon, ovary, and lung, Hodgkin's disease, several soft-tissue sarcomas, brain tumors, and rectal polyps, which are benign at first but may later become malignant.
Reporting for his four-man research team, Dr. Grace described an elaborate effort to find something in human cancer that would multiply in tissue culture (as the polio and polyoma viruses are grown) and would then cause cancer when injected into animals. In 13 months, with 1,000 mice, the effort failed. But the researchers also took material from 125 cancer victims, processed it rigorously to exclude cell fragments and all known viruses, then injected what was left directly into newborn mice and hamsters. The results were startling.
Years & Millions? Of about 1,600 mice so treated, 150 have
developed tumors within six months. The "take" was greatest
(50%) with material from a nerve-cell tumor, is also high (18%)
with acute leukemia. The take is low with extracts from human
breast cancer. Yet 90% of the mouse tumors have been cancers of
the breast, showing that the site of the original cancer has
little or nothing to do with where the material will induce
cancer. Also striking is the fact that many mice develop
multiple tumors. Some of these depend for their growth on the
animal's hormone balance (one gravid mouse developed a 2-cm.
tumor that disappeared after she littered, then recurred and
killed her when she was bred again). But not all: Dr. Grace's
team produced several breast tumors in males—as rare in mouse as