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Percutaneous Radiofrequency Ablation of Tumors in the Liver and Kidney
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- Percutaneous radiofrequency ablation (RFA) may be considered for biopsy-confirmed tumors that
cannot be resected or when patients are not good candidates for surgery
- RFA is most effective for tumors <2.5 cm diameter positioned away from large blood vessels and
vital structures (e.g. colon, ureter)
- Treatment outcome for 1º liver cancers (hepatocellular cancer) is generally good
- There is significant risk of local recurrence of disease when metastases to the liver from colon
cancer are treated
- RFA treatment of renal cell carcinoma is promising but long term follow-up data is not available
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Surgical
resection of tumors is the established method of treatment for renal
cell carcinoma, primary liver cancers, and isolated metastases from
colorectal carcinoma to the liver. However, resection is not always
possible because of the position of the tumor, the extent of disease,
or patient co-morbidities. Percutaneous radiofrequency ablation (RFA)
is relatively new treatment that is suitable for many patients for whom
resection is not possible. The benefits of RFA over resection include
reduced treatment related morbidity and mortality, preservation of more
functional tissue in the organ, and outpatient treatment. The first
clinical application of percutaneous RFA in the United States for a
liver tumor was performed at MGH in 1996 and the first percutaneous RFA
treatment of a renal tumor at MGH was in 1998. Consequently, the data
on treatment outcome is limited and more follow-up studies are needed.
Indications for Liver Tumor RFA
Percutaneous RFA is most effective on tumors < 3 cm (but tumors up
to 5.5 cm may be considered for treatment) deep within hepatic
parenchyma and remote from large blood vessels, which can cool the
tissue and prevent full ablation. If the tumor is close to the hepatic
hylum, then RFA may damage a central bile duct, causing atrophy and
jaundice. If the tumor is close to a vulnerable structure, such as the
diaphragm or the gut wall, there is risk of RFA damage and subsequent
perforation. RFA can be combined with surgery of larger tumors and
ablation of smaller tumors.
Percutaneous RFA is best suited to patients with unresectable primary
liver cancer (hepatocellular cancer), who usually are cirrhotic. It can
also be considered for patients with unresectable liver metastases from
colorectal cancer when there is no |
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Transverse
CT image showing RFA electrode (arrow) in a renal tumor. A second tumor
contains a biopsy needle that was removed before RF ablation was
performed.
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evidence of tumors elsewhere. In addition, RFA may be considered for
patients with liver metastases from other primary cancers (e.g. breast,
esophageal) although they are more likely to have occult disease in
other tissues. In addition, patients with symptomatic neuroendocrine
tumor liver metastases will benefit from RFA as it will reduce symptoms
and improve the quality of life.
From the available data, outcome for patients with hepatocellular
tumors, when they are slow growing and encapsulated, appears to be
excellent. However, it is difficult to compare the effectiveness of RFA
with resection because those that who are treated with RFA generally
have a greater number of lesions and/or co-morbidities. Nevertheless,
published studies suggest that patients with single primary liver
tumors < 3 cm in diameter have a comparable survival rate after
surgery or RFA.
For patients with metastatic colorectal cancer, the risk of local
recurrence of disease after ablation of tumors <2.5 cm is about 20%
and about 70% for tumors greater than 4 cm.
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Indications |
Limitations |
| General |
Patients not candidates for surgery
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Maximum tumor diameter, 5.5 cm
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Tumors must be accessible percutaneously
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Maximum number of tumors, 3-4 tumors with none > 4 cm
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Contraindicated in cases of sepsis, severe debilitation, or uncorrectable coagulopathy
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| Liver Tumors |
1º liver cancers (hematoma and hepatocellular cancer), including those in cirrhotic patients
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Proximity to vital structures, e.g. bowel, diaphragm, bile duct (danger of perforation, obstruction)
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Neuroendocrine tumors (to debulk and reduce symptoms)
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Proximity to large blood vessels (incomplete ablation due to cooling effect) |
Metastatic disease from colon cancer
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| Renal Tumors |
Single functional kidney
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Proximity to colon or small intestine
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Biopsy confirmed renal cell carcinoma tumors in peripheral location and no metastatic disease
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Proximity
to large vessels or ureter (danger of ureteral damage and increased
likelihood of incomplete ablation due to cooling effect.)
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Life expectancy > 1 yr and < 10 yrs
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Indications for Renal Cell Carcinoma RFA
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Indications
for RFA include renal cell carcinoma in patients with co-morbidities
that preclude surgery, a solitary kidney, or a minimally functioning of
contralateral kidney, or co-morbidities that preclude surgery. Patients
must be screened by a urologist who must confirm the diagnosis by
biopsy and show that the disease is confined to the kidney, with no
extra-renal extensions, vascular invasions or metastases. Since the
kidney is surrounded with fat, which has limited blood supply for
cooling, the effectiveness of RFA for exophytic tumors is high.
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In
contrast, tumors that are near the renal sinus are close to large blood
vessels that serve as heat sinks and ablation is less likely to be
completely successful. In addition, there is risk of ureteral damage.
Although, there is limited data on survival, experience at MGH
indicates that percutaneous RFA of exophytic renal tumors < 5
cm is a highly promising treatment. |
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Advantages |
Disadvantages |
| Resection |
More complete data on survival
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Major surgery requiring several day hospital stay and 6 week recovery
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Lower likelihood of local disease recurrence in metastatic colon cancer
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Complications of liver tumor resection include bleeding, jaundice, bile leak, and those resulting from prolonged bed rest
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Mortality after liver tumor resection, <2%
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| RFA |
Low complication rate
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Major
complication rate of liver tumor RFA, 2% (hemorrhage, neoplastic
seeding, intrahepatic abscesses, jaundice, intestinal perforation)
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Outpatient procedure for 80% of cases
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Little post-procedural pain
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Mortality rate of RFA of liver tumor, 0.3%
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Complications
of renal tumor RFA include microscopic hematurea, pain, urinary
fistula, or ureteral obstruction requiring stent or nephrostomy tube
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Patient Preparation and Procedures
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Standard
staging protocols required before RFA ablation include a pre-ablation
image study (CT or MRI), a chest radiograph or CT, bone scintigraphy,
tumor biopsy, and evaluation by a urologist for renal tumors or a liver
surgeon for liver tumors. RFA is normally performed as an outpatient
procedure but patients may be admitted prior to the treatment if
coagulopathy needs to be treated. If patients are on anti-coagulant
therapy, they must cease prior to the procedure. No food or drink may
be taken for at least six hours prior to treatment.
The RFA procedure is carried out with the patient under conscious
sedation and local anesthetic. Selected patients may require general
anesthesia if they do not meet the criteria for conscious
sedation. Under CT guidance (or US guidance if the entire tumor
and adjacent structures can be seen this way) a radiofrequency
electrode the size of a 17 gauge needle is inserted into a tumor. Once
in place in the center of a tumor, a 490-500 kHz alternating current is
applied, which generates radiofrequency and heat at the tip of the
electrode. The surrounding tissue is heated to 50-100ºC and maintained
at that temperature for sufficient time
to cause irreversible cell damage and necrosis of the tumor. Each
treatment can ablate a roughly spherical region up to 3-4 cm in
diameter. Tumor and ablation geometry is usually irregular and, in
order to decrease the risk of tumor recurrence, some normal tissue is
usually ablated to 0.5-1 cm beyond the tumor margin.
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The
ablated tissue remains in place and, over time, is absorbed and
replaced with scar tissue. Total treatment time is 1-2 hours. At the
time of the procedure, it is not possible to assess treatment success,
which is determined on follow-up.
After the
procedure, patients rest for a few hours while being closely monitored
for signs of complications. After this time, they will be able to go
home provided that there are no signs of bleeding or other
complications. If any complications occur they will stay in hospital
overnight or until well enough to go home.
All patients need follow-up imaging (usually a CT or MRI) after 1 month
to assess the success of the RFA. Complete ablation in one treatment is
more likely if the tumor is small. In patients with liver tumors,
30-55% of patients with tumors 3.1-5.0 cm in diameter and 75-85% of
those with tumors greater than 5.0 cm can expect to need a second
treatment to complete ablation. For patients with renal cell
carcinoma, <10% return for a second ablation treatment if their
tumor was <3 cm, whereas 30-40% return if their tumor was 3-5 cm in
diameter.
When tumor ablation appears complete, patients should return for
follow-up scans at 3 months, 6 months, and 1 year. After that,
follow-up of those with liver cancer should continue at six monthly
intervals and those with renal cancer should continue annually.
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Liver Tumor Before RF Ablation - The tumor (arrow) in the liver takes up contrast material which is white on CT scan.
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Liver
Tumor After RF Ablation - After RF ablation, the tumor (arrows) no
longer takes up the contrast material. If part of the tumor had
continued to take up contrast material, that part could be treated
again with RF ablation.
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Scheduling
Before
an RFA procedure can be scheduled, patients are first evaluated by a
urologist for renal tumors or a liver surgeon for liver tumors,
respectively. Appointments for an RFA procedure are made through the
nurse coordinator in the Interventional Radiology Clinic, 617-724-2239.
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Further Information
For further questions on RFA, please contact Debra A. Dervais, M.D., Abdominal and Interventional Radiology, (617-726-8396), Kenneth K. Tanabe, M.D., Surgical Oncology, (617-724-3868) or Francis J. McGovern, M.D., Urology, (617-726-3650). More information on RFA is also available on the Radiology website.
This article provided useful information about the appropriate use of imaging studies:
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References
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Gervais, DA, McGovern, FJ, Arellano, RS, McDougal, WS and Mueller, PR. (2003) Renal cell carcinoma: clinical experience and technical success with radio-frequency ablation of 42 tumors. Radiology 226: 417-24
Livraghi, T, Goldberg, SN, Lazzaroni, S, Meloni, F, et al.(2000) Hepatocellular carcinoma: radio-frequency ablation of medium and large lesions. Radiology 214: 761-8
Lui, KW, Gervais, DA, Arellano, RA and Mueller, PR. (2003) Radiofrequency ablation of renal cell carcinoma. Clin Radiol 58: 905-13
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Solbiati, L, Livraghi, T, Goldberg, SN, Ierace, T, et al.(2001) Percutaneous radio-frequency ablation of hepatic metastases from colorectal cancer: long-term results in 117 patients. Radiology 221: 159-66
Tanabe, KK, Curley, SA, Dodd, GD, Siperstein, AE and Goldberg, SN. (2004) Radiofrequency ablation: the experts weigh in. Cancer 100: 641-50
Vivarelli, M, Guglielmi, A, Ruzzenente, A, Cucchetti, A, et al. (2004) Surgical resection versus percutaneous radiofrequency ablation in the treatment of hepatocellular carcinoma on cirrhotic liver. Ann Surg 240: 102-7
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