Continuing War

Cancer fighters long ago reconciled themselves to a long war of attrition. They do not hope to find a miracle cure, but they do expect their present slow progress to continue. In Atlantic City last week, at the annual meeting of the American Association for Cancer Research, one scientist cracked: "The progress of cancer research depends on how fast mice reproduce." (Usual breeding rate: one litter every 20 days or so.)

For the 180,000 U.S. men, women & children who will die this year from cancer, the 250 scientists at the meeting had no definitely cheery news. After listening to the advice of the Association's retiring president--"Be cautious with your data"--they cautiously reported some mouse-paced progress, measurable in millimeters.

Zymohexase. A new way of detecting cancer in laboratory animals was reported by Drs. John A. Sibley and Albert L. Lehninger of the University of Chicago. They found that whenever an active tumor is present, the blood contains an abnormally large amount of an enzyme called zymohexase; when the tumor is removed, the amount of zymohexase returns to normal. Some day, they thought, the test might be valuable for detecting human cancer.

Porphyrins. A test that may also make treatment easier was described by Dr. Frank H. J. Figge, of the University of Maryland. He set out to find a way of carrying radioactive isotopes directly to a tumor without damaging the rest of the body on the way. Experimenting with porphyrins, which are fluorescent substances found in the body in minute amounts, he found that they went directly to cancer tissue. Since they stay on its outer limit and since they glow under ultraviolet light, they neatly outline the tumor. The porphyrins could, Dr. Figge found, carry zinc on their journey; that indicated that they might also carry isotopes.* One drawback to porphyrins as isotope carriers: they also have an affinity for the necrotic (dead) parts of a cancer, where radioactivity would do little, if any, good.

L-Alamine. A radioactive isotope of carbon has carried three doctors from Boston's Huntington Hospital a little farther toward showing just how cancer cells and normal cells differ. Drs. P. C. Zamecnik, I. D. Frantz Jr., and R. B. Loftfield tagged a protein-building amino acid called l-alzmine with the isotope, watched what cancer tissue and normal liver tissue did with it in test tubes. They found that cancerous livers absorbed the amino acid much faster than normal livers. Eventually, their experiments might help explain why cancer cells grow disastrously faster than normal cells.

Polysaccharides. Cancers in mice have been destroyed by some bacterial polysaccharides (enormous sugarlike molecules derived from bacteria), reported Dr. Hugh J. Creech of Lankenau Hospital's Research Institute in Philadelphia. Drawbacks: 1) repeated doses have little or no effect because the mice build up an immunity to the substance; 2) doses high enough to bypass the immunity may kill the mice as well as the cancer.

*Radioactive isotopes, produced at Oak Ridge, Term., are now being shipped by the U.S. to Argentina, Australia, Canada, Denmark, Great Britain, Italy, Peru, Sweden. Russia asked for isotopes, but apparently dropped the idea when she learned the conditions: reports twice a year, free inspection by interested scientists.

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