In a Guinea Pig's Eye

Why does a cancer behave differently from normal tissue? At Yale University's Medical School, a lanky, greying pathologist named Harry Sylvestre Nutting Greene is looking for an answer to this basic question.

Dr. Greene's "laboratory" is a guinea pig's eye. Delicately, he plants various types of foreign tissue in the pigs' eyes. Some "take" and grow. Sometimes the transplanted tissue becomes cancerous. Sometimes it develops the characteristics of functioning organs. Cancer specialists, who used to be skeptical, have begun to take a lively interest in Dr. Greene's work. Last week the doctor talked about it before a distinguished audience at the American Cancer Society's annual meeting in Manhattan.

Cancer tissue, as researchers have long known, can easily be transplanted from one mammalian species to another. When Dr. Greene grafted human cancer tissue on a guinea pig's eye (a nourishing and easy-to-watch site for experiment), the transplanted cancer thrived in its new environment. But his efforts to transplant normal adult human tissue to the guinea pig's eye failed.

That gave the doctor an idea. Under the microscope, one type of normal animal tissue--embryonic--closely resembles cancer. Dr. Greene planted some embryonic tissue in guinea pigs' eyes. It worked. In a guinea pig's eye, transplanted embryonic breast tissue gave milk, tissue from the testes produced sperm.

Cancer and embryonic tissues are the only ones that can be successfully transplanted from man to other animals. Does that mean that they are one & the same? Dr. Greene suspects that they may be; the only difference between cancerous and embryonic tissue that he has discovered is that embryonic tissue grows up and "differentiates," i.e., acquires a special function. It is possible, he suggests, that cancer is merely arrested embryonic tissue.

If Dr. Greene is right, a cure for cancer may depend on finding the unknown factor that arrests the development of embryonic cells. To prove that there is only a thin dividing line between embryonic tissue and cancer, he treated embryonic tissue with cancer-inducing chemicals and implanted the treated tissue in animals. Result: the animals developed cancers in record time.

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