Three researchers, including an assistant professor at the Medical School, have discovered a substance in the urine of bladder-cancer patients which they believe may promote the growth of malignant tumors.

The researchers contend that the substance creates new capillaries around a tumor, feeding it with a constant flow of blood.

"We hypothesize that all solid tumors make this kind of substance. Our primary goal is to identify it and purify it," Bruce R. Zetter, one of the researchers and assistant professor of Microbiology and Molecular Genetics in surgery at the Harvard Medical School, said yesterday.

If the scientists identify the substance, the discovery could lead to two possible cancer treatments; an antibody to counter the effects of the substance or a technique to prevent the migration of capillary tissue from healthy to malignant areas, Zetter said.

He added that the research may allow doctors to detect bladder tumors before they form.

Gerald W. Chodak, a urologist at the University of Chicago, and Cathy J. Scheiner, a graduate student at MIT, conducted the research with Zetter.