A Johns Hopkins doctor is extending the lives of inoperable liver cancer patients by making them temporarily radioactive while powerful radiation is delivered directly to their cancers.

Their tumors have so far remained ultimately fatal. But in an advanced stage of disease where survival is usually only three to seven months, Johns Hopkins' Dr. Stanley Order has achieved remissions that lasted as long as 18 months and survival as long as two years.

And in seven of eight liver cancer patients so far treated, tumor size has been reduced drastically -- from 70 to 18 percent of the liver in one case and from 50 to 5 percent in another.

"We haven't cured anyone yet" by this method -- attaching a radioactive chemical to cancer-fighting antibodies made in rabbits -- Order said, "but we've doubled average survival, and we're rapidly improving our methods."

The new technique floods the liver with continuous radiation for days or weeks, rather than brief bursts, which is the usual treatment.

To do this, a protein made by liver cancers is extracted, purified and injected into rabbits. The rabbits then make antibodies -- disease-fighting proteins -- against the cancer protein.

The rabbit antibodies are then heavily dosed with radioactive iodine and injected into the patient. The antibodies then attach themselves to the liver cancer, and the radioactive material begins its destructive work.

Order is trying the same treatment in lung cancer, neuroblastoma (a cancer of the nervous system in children) and multiple myeloma, all of which make the same protein, ferritin, that liver cancers produce.

And the Hopkins doctors have begun using new purification methods to make rabbit serum that is six to eight times more specific and potent than their first serums.

"We are about five years away from establishing the basic ground rules for this kind of treatment," Order said. "But we think our preparations offer new hope, which might potentially make all human cancers targetable."