Researchers at Harvard Medical School and Massachusetts General Hospital (MGH) believe they have identified a cancer factor released in the bloodstream that can serve as the basis for a highly effective test for certain kinds of cancer.

The test could potentially help doctors detect cancers in patients who are in a high risk category or show symptoms of cancer development, Dr. Alfred M. Cohen, assistant professor of surgery, said last night.

It will be very useful in monitoring patients after cancer-related surgery, he added.

The cancer factor measured in the new process is an isoenzyme called GT-II, which malignant cells release in greater quantities than normal cells.

The advantage of GT-II as a testing factor is that it combines sensitivity to screening with high specificity for cancer, Cohen said. In preliminary studies the test has shown a 73 to 83-percent accuracy.

The new technique looks most promising in detection of pancreatic tumors, Cohen said. Cancer of the pancreas is "becoming a major national health problem," he said, adding that because early symptoms are very subtle, it has had a fatality rate of 99.5 per cent.

"We're hoping other people more equipped to do the work will undertake a large scale clinical study," Dr. Daniel K. Podolsky '74, one of the researchers, said yesterday.

Cohen, who is also co-director of cancer research at MGH, said another serum test under study that appears to be 80 per cent accurate is "very exciting with regard to brain tumors."