RFA has been used most often in relation to liver tumors, since so many of thesetumors are ineligible for surgery. The procedure has been approved by the FDAsince 1996 and is covered by many insurance carriers. Some researchers suggestthat RFA could replace surgery altogether for the treatment of liver lesions.
Currently, RFA is most frequently used to eliminate both primary and metastaticliver tumors between 0.5 and 3 cm in size. It is most effective when there areno more than three tumors per site. With more widespread disease, the treatmentis less effective at prolonging life.
In many cases, RFA is used to reduce or eliminate pain caused by tumors, not tocure the cancer itself. However, researchers in Italy have found that thesurvivability rates for patients whose liver tumors were treated with RFA aresimilar to, if not better than, those for patients whose tumors were treatedwith surgery. These researchers and others are beginning to recommend RFA as thefirst-line treatment for all liver tumors.
In addition, new research suggests that RFA in combination with other therapiescan treat larger tumors of the liver. A study from Memorial Sloan-KetteringCancer Center found that a combination of chemoembolization and RFA was aseffective as surgery in treating single primary liver tumors.
Unlike its use in soft-tissue tumors, RFA is used almost exclusively as apalliative remedy to improve quality of life, not as a way to increasesurvivability rates. The technique may completely eliminate small tumors lessthan 3 cm in size, but it can also be used to shrink tumors up to 10 cm indiameter.
Both RFA and cryoablation have been shown to reduce pain caused by bone tumors.Research presented at the 2005 Society of Interventional Radiology conferenceshowed that RFA and cryoablation can reduce pain by as much as 89% in patientswith nonresectable bone tumors.
RFA is showing impressive results in treating lung tumors. It is most effectiveon tumors that are less than 4 cm in size.
A recent study in Italy indicated that RFA of lung tumors can dramaticallyincrease survivability rates without decreasing quality of life. Doctors foundthat RFA killed tumors in the lung in 93% of cases, and patients hadcancer-specific one- and two-year survival rates of 91%.
Five-year survivability rates from multicenter trials are not yet available.Some limited studies show cancer-specific five-year survivability rates of up to60%.
RFA can be used to treat tumors that originate in the kidneys and those thatmetastasized from other organs. The procedure is often used to treat tumors inthe remaining kidney when one kidney has been removed.
RFA is most effective on kidney tumors between 0.5 and 3 cm in size, and no morethan three in number. The technique is promising, but long-term studies areneeded to prove how effective it is.
The procedure has not been performed long enough or widely enough to producemulticenter five-year survivability data. However, research at MassachusettsGeneral Hospital found that RFA shows promise for treating kidney tumors nearthe surface of the organ. The investigators followed 34 patients over a 3.5-yearperiod and found that 31 of 42 kidney tumors--all located near the kidneysurface--were completely destroyed with RFA.
Some researchers suggest that RFA may be a viable replacement for lumpectomy,but results of long-term studies are pending.
Where RFA Should Not Be Used
While RFA and other tumor ablation treatments show great promise, they shouldnot be used in every situation.
o Blood vessels
RFA and other heat ablation procedures can be ineffective when used on tumorsnear major blood vessels. This is due to the "heat sink" effect: The bloodvessels can carry the heat away from the treatment area, causing inconsistenttissue heating. In this case, all areas of the tumor may not receive the sameamount of heat, so some areas may not be destroyed.
o Nerve endings
RFA may not be used when a tumor is located near major nerve centers. Nerveendings are highly susceptible to heat, and the treatment may inadvertentlydestroy the nerves while killing the tumor.