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LETTER TO THE EDITOR |
Department of Surgery, University of Hawaii at Manoa and Kuakini Medical Center Honolulu, Hawaii.
With interest, I read an article by Dr. Sharon M. Weber and associates, titled "Survival After Resection of Multiple Hepatic Colorectal Metastases" published in the Annals of Surgical Oncology.1 They have shown excellent results of aggressive surgical resectional treatment of four or more metastatic tumors from colorectal cancer. Their findings are important because this number of multiple metastases has been considered to be a relative contraindication to hepatic resection. The morbidity and mortality of their experiences are excellent, as well as the long-term survival. Obviously, their results suggest that this kind of aggressive surgical approach is justified in selected patients. However, I think, many surgeons are not yet willing to perform surgical resection of bilobar metastatic tumors of more than four or five in number. Hepatic resection is still a major surgery, and a low morbidity and mortality achieved by experts like Dr. Weber and associates may not be possible by many general surgeons.
As mentioned in their discussion, the use of radiofrequency thermal ablation (RFA) has been investigated over the last several years. This new modality has been used mainly for unresectable hepatic tumors. The main advantages of RFA treatment are its relative safety, less invasiveness, and the capability of percutaneous approach. Although bleeding and infectious complications are major risks for hepatic resection, these complications are rare with RFA. The local recurrence rate because of ablation treatment failure has been reported to be about 10%, even as low as 2%,2–4 although the long-term results of this ablation are not available at this time. Another advantage of RFA is that it can be used for tumors that invade or are adjacent to major intrahepatic vascular structures that cannot be resected with an adequate or negative margin.
In their discussion, they have described that most surgeons who perform local ablation are unwilling to treat more than three to five tumors or lesions greater than 4–5cm in size. I believe that this statement is not necessarily true. I know that some investigators of RFA have been treating more than five tumors and ones that are greater than 5 cm in size. In my experience with RFA of more than 100 operations for more than 300 hepatic tumors, the average size of the tumors was 36 mm, and about one third of the tumors were greater than 5cm in size.5 Also, in about one third of the operations, four or more tumors per operation have been ablated.
Multimodality treatment is required, as they mentioned, to obtain the best chance for cure in patients with colorectal hepatic metastases. Surgical resection and ablation methods are the modality for local control. Even with these local control methods, many patients develop new recurrent tumors in the liver that are diagnosed at follow-up. Regional and/or systemic chemotherapy may decrease such hepatic recurrence. However, once these recurrences occur in the liver, another controversial issue is the indication for re-resection or repeat resection. In my experience and also that of other investigators, RFA can be repeated many times because of its relative safety. In particular, repeat percutaneous RFA is less invasive and is more acceptable to patients who have already had previous major operations. Also, RFA can be safely performed for synchronous multiple hepatic metastases in conjunction with colorectal resection for primary cancer.6
The major factors that contribute to local recurrence after RFA are the size of the tumor and the tumor invasion to vessels. However, in my experience, more than 50% of the tumors with major vascular invasion did not show any local recurrence after RFA. For the large tumors, multiple overlapping ablation sessions are required, which in turn increase the rate of local recurrence. Therefore, for large hepatic tumors, surgical resection is preferable if technically possible. For multiple bilobar tumors, combination of surgical resection and ablation treatment (e.g., lobectomy for tumors including large ones in one lobe in conjunction with RFA of tumors of the other lobe) is a good approach. We surgeons should try to control all gross tumors by resection and/or ablation method. While operative technique and perioperative care for resection has been improving, the technology for RFA has been and will continue to improve. The original RFA devices were able to ablate tumors to about 3–3.5cm in size in one session. Currently, newer devices are able to ablate up to 5 cm. Manufacturers are making an effort to further increase the size of ablation with this RFA technique. Dr. Weber and associates have shown that metastatic tumors that have been previously considered unresectable can be resected by aggressive surgical approach. Likewise, I believe that with appropriate applications, RFA will increase the treatability or resectability of hepatic tumors that previously would have been considered untreatable.
REFERENCES
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