SAN FRANCISCO - With radiofrequency ablation showing great promise as a safe and effective way to treat liver metastases, colorectal surgeons would do well to rely on the expertise of their radiology counterparts, according to a surgical oncologist from M. D. Anderson Cancer Center in Houston.
"As surgeons, we’re trained to think that we can do everything as well as anybody else," said Dr. Lee Ellis in a presentation at the "Perspectives in Colorectal Cancer" conference in San Francisco on September 9. "I actually work very closely with an ultrasonographer [when performing radiofrequency ablation] because I believe that somebody who does ultrasonography five days a week, all day long, is going to do it better than I am."
Ultrasound plays a vital role in the mechanics of radiofrequency ablation (RFA), guiding and positioning the electrode for maximum accuracy.
"Just like real estate, what’s critical is location, location, location," Ellis said. "When you are placing that array, it has to be perfect. You cannot afford to be half a centimeter off."
Radiofrequency ablation could be the best hope for patients with liver cancer as a result of primary colon cancer. About half of patients with primary colon cancer will develop distant metastases, with the majority appearing in the liver, Ellis said. However, "only 4% to 5% of those will be resectable," he added.
What makes RFA more appealing than other treatment techniques, such as cryotherapy, is that there is no electrocautery. "No heat flows directly from the device. It’s a high frequency, alternating current that heats the tissues, which then causes the destruction of the tumor," Ellis explained.
In contrast, cryotherapy, which directly cools and re-heats the tumor, can result in such complications as bleeding (mean loss of 750 cc), liver cracking, and acute renal failure, Ellis said.
Whether RFA is done as an open technique or laparoscopically, ultrasound-guidance is critical. Surgeons must be able to not only ablate the tumor, but the surrounding rim of the hepatic parenchyma as well, Ellis said. In addition, tumors must be visualized as 3D objects requiring several passes with the array in order to achieve complete ablation, Ellis said.
While RFA does have some limitations -- tumors larger than 4 cm cannot be ablated until larger arrays are on the market; RFA does not alter the natural history of metastases –- it is shaping up to be part and parcel of the liver cancer treatment protocol, Ellis concluded.
Recently published studies certainly support Ellis’ theory. According to radiologists at Massachusetts General Hospital in Boston, radiofrequency ablation scored high marks in a study of 22 patients with liver cancer. After three days, the specimens that were ablated and then removed showed "definite, contiguous coagulative necrosis without intervening areas of viable tumor (Cancer, June 1, 2000, Vol. 88:11, pp. 2452-2463).
In a larger study with 123 patients from the M. D. Anderson Cancer Center, RFA was deemed a "safe, well-tolerated, and effective treatment to achieve tumor destruction in patients with unresectable hepatic malignancies." In this study population, 169 tumors were treated with no treatment-related deaths and a 2.4% complication rate (Annals of Surgery, July 1999, Vol. 230:1, pp.1-8).
Finally, a joint study by the M. D. Anderson team and the G. Pascale National Cancer Institute of Naples, Italy found that only four out of their 110 patients with hepatocellular carcinoma experienced local tumor recurrence after RFA treatment (Annals of Surgery, Sept. 2000, Vol. 232:3, pp. 381-391).
By Shalmali PalAuntMinnie.com staff writer
September 12, 2000
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Update on interventions for malignant liver tumors, February 15, 2000
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