Putting the freeze on liver tumors.

Putting the freeze on liver tumors

For nine out of 10 people whose coloncancer has spread to the liver, there is essentially no treatment. Their tumors are either too close to major blood vessels or too numerous to allow conventional surgery. And "there is no effective treatment other than surgery,' says Gary Onik, a radiologist at Allegheny General Hospital in Pittsburgh. "There is nothing we can do for them.'

Now Onik and his colleagues offer a rayof hope for some of the 50,000 people diagnosed with this form of liver cancer each year in the United States. They have developed a new surgical procedure that destroys liver tumors while leaving most of the liver tissue and blood vessels intact. The technique combines two existing surgical tools: the cryoprobe, which freezes and kills tumors, and ultrasound, which images tumors and guides the cryoprobe.

Of the seven patients on whom thisprocedure has been tried, reports Onik, four show absolutely no evidence of having the disease today. The longest follow-up time so far is 14 months, he says. He discussed the findings in Edmonton, Alberta, at a recent meeting of the Society for Cryobiology.

Oncologist Robert J. Mayer of the Dana-FarberCancer Institute in Boston says the procedure is "a promising technique that will probably prolong survival in patients who are unresectable [can't have their tumors cut out]. But I doubt very much that it will cure people and I don't think it will be a substitute for surgical resection.'

Onik, however, points out that withoutcryosurgery, the four unresectable patients now in remission would have died. Moreover, he suspects that the cryosurgery will be at least as effective as resection, which has a "cure rate' (meaning patients are living and the cancer has not spread to other parts of the body) of about 25 percent after five years. He also notes that cryosurgery involves far less blood loss, and animal studies suggest that by leaving the killed tumor in place, cryosurgery may help the body's immune system identify and destroy escaping cancer cells.

Surgeons routinely use cryoprobes--in which circulating liquid nitrogen cools tissues to -196|C--for treating skin cancers and other medical problems in easily accessible parts of the body. With ultrasound, Onik's group has extended cryosurgery's potential to solid organs in far less accessible spots.

The researchers are working to applytheir technique to tumors in the kidney and brain. They've also developed, and plan to try soon, a new procedure for prostate tumors, which they believe will avoid the complications associated with conventional prostate surgery.