By Melanie Fridl Ross
Gainesville, FL --- The hottest new weapon in the surgeon's arsenal against liver cancer uses heat instead of cold, a shift that could put the freeze on what until now has been the standard therapy for inoperable tumors. What's more, it's easy, cheap and considerably less risky to perform than surgery or using cold to zap malignancies.
Now University of Florida researchers have found that the technique, known as radiofrequency ablation, does not initiate a cascade of harmful hormones that often causes patients who undergo the alternative -- cryotherapy -- to go into shock. Surgeons are scheduled to report the new findings Saturday (2/3) at the annual scientific meeting of the Southeastern Surgical Congress in New Orleans.
"An unfortunate byproduct of cryotherapy is people will develop a form of shock related to the treatment, which has to do with the fact that circulating hormone levels in the body increase and cause a bad systemic reaction, similar to massive overwhelming infection," said Dr. Scott Schell an assistant professor of surgery and of molecular genetics and microbiology at UF's College of Medicine and the UF Shands Cancer Center.
Last summer, the Food and Drug Administration approved the use of radiofrequency ablation, traditionally used to correct heart arrhythmias, for the treatment of liver tumors. For terminally ill liver cancer patients with no other options, the approach offers an alternative that helps slow the disease process, improving their quality of life, Schell said.
"These are patients who basically have no other hope," Schell said. "We are able to help set back the clock using radiofrequency ablation."
Of the estimated 150,000 patients who will be treated for colorectal cancer this year, about half will suffer a recurrence within five years. Less than a third of those people will respond to chemotherapy, and of the tumors that return, most spread to the liver. Chemotherapy doesn't always work and a substantial number of these growths will be inoperable. Even those patients who are candidates for surgery face an uphill battle.
"In the past, we've treated patients who can't undergo surgery because of the number of tumors, the total volume of the tumors or the closeness of tumors to major vascular structures within the liver with cryotherapy," Schell said. "We place a stainless steel tube into the middle of the tumor and pump liquid nitrogen into the tumor in order to freeze it to death. That works pretty well, but it's cumbersome and expensive to perform, and it can't be done laparoscopically (through small incisions)."
Radiofrequency ablation, on the other hand, uses a small needle to deploy an antenna into the center of the tumor.
"Through this antenna we deliver radio energy that acts to kill the tumor cells by heating them up so hot that proteins are destroyed, similar to how an egg white is coagulated during a cooking procedure," Schell said. "So as a result, these tumor cells are basically cooked to death."
To date, UF surgeons have used radiofrequency ablation on nearly a hundred patients. For their most recent study, they evaluated nine patients ages 40 to 85 who had inoperable liver tumors. Surgeons measured blood levels of inflammatory hormones during radiofrequency ablation and 48 hours after the procedure, when hormones typically wreak their maximum insult, Schell said.
Radiofrequency ablation didn't incite the systemic inflammatory responses commonly seen with cryotherapy. Their findings mirror results from studies involving rodents.
"Remarkably, there was no significant elevation in these hormone levels," Schell said. "We have seen quite plainly why these people are not getting sick. These findings are novel and have never before been reported in patients."
In addition, the risk of adverse effects or death from the procedure is dramatically lower, while the results appear to be equivalent or even superior to those seen with cryotherapy or liver surgery, Schell said.
Dr. Steven A. Curley, a professor of surgery and chief of gastrointestinal tumor surgery at the University of Texas M.D. Anderson Cancer Center, said the UF findings have merit. "Our work at M.D. Anderson clearly shows that the complications and risks of radiofrequency ablation of malignant liver tumors are significantly lower than with cryoablation of liver tumors," Curley said. "The work performed by Dr. Schell and colleagues at the University of Florida confirms what I have suspected, that is, that radiofrequency ablation of liver tumors does not activate systemic inflammatory mechanisms, which helps to explain the much lower incidence of side effects in these patients when compared to (those who undergo) cryoablation."
Schell collaborated with UF researchers Dr. Frank J. Wessels, senior resident in the department of surgery; Lyle L. Moldawer, a professor of surgery and director of surgical research; and Dr. Edward M. Copeland III, a professor of surgery and chairman of the department of surgery at the College of Medicine.