In a radical, and welcome, change in research methods, some scientists are swapping mice for a new procedure in testing anti-cancer drugs.

The new system tries out drugs on real human cancer cells rather than on mice or other hapless laboratory animals. The idea behind this change is that cancer cells from a specific organ may share characteristics with other cancer cells from the same organ.

Now a new National Cancer Institute screening process uses computers and other automated equipment to test potential cancer drugs against 60 lines of living human tumor cells grown in Petri dishes and representing seven deadly cancers.

While testing on animals may still be necessary, this new approach should substantially broaden the weaponry to be used against cancer. It also suggests the arguments of activists - that a wide variety of alternatives exists to animal experimentation - are turning out to be true.