2012 EDUCATIONAL BOOK - American Society of Clinical Oncology

The Interventional Radiologist Role
in Treating Liver Metastases for
Colorectal Cancer
By Stephen B. Solomon, MD, and Constantinos T. Sofocleous, MD, PhD
Overview: Interventional radiologists (IRs) have an expanding
role in the treatment of liver metastases from colorectal
cancer. Increasing data on the ability to treat liver metastases
with locoregional therapies has solidified this position. Ablative
approaches, such as radiofrequency ablation and microwave
ablation, have shown durable eradication of tumors.
Catheter-directed therapies—such as transarterial chemoembolization
(TACE), drug-eluting beads (DEB), Y90 radioembo-
INTERVENTIONAL RADIOLOGISTS have an expanding
role in the treatment of liver metastases from colorectal
cancer. Understanding the various locoregional treatment
options and their integration into the care of the metastatic
patient is important for good oncologic care. This review will
describe some of these treatment options and their existing
supportive data.
Ablative Therapies
Patients undergoing liver resection of their colorectal metastases
have prolonged survival. 1 However, only approximately
20% of patients with liver metastases are surgical
candidates. 2 Ablation technologies cause focal destruction of
tissue, and when coupled with imaging guidance, this targeted
destruction can be aimed at a particular metastasis.
Similar to surgical resection, the goal of ablation is to create
a margin of destruction around the targeted tumor to prevent
recurrence. There are a number of ablative tools available—including
radiofrequency ablation (RFA), microwave
ablation, cryoablation, laser ablation, and focused ultrasound
ablation—that rely on extreme temperature conditions
of heat or cold to exact the tissue damage. 3 A new,
nonthermal technique called irreversible electroporation
uses electric fields to cause cell death without apparently
harming tissue protein architecture that makes up structures
such as bile ducts and vessels. This technique may
open up new ablative opportunities near critical structures
that were previously risky using thermal ablation tools,
which could potentially damage these critical structures.
Also, this nonthermal technique may be more effective than
thermal ablation techniques near blood vessels where thermal
techniques suffer because of a “heat sink effect” that
limits how hot the tissue adjacent to a vessel can get. 4 More
research is needed to better understand this modality. The
technical differences among all of these techniques is beyond
the scope of this review, suffice it to say, that RFA has been
the most commonly used technique with the most extensive
literature for treating liver metastases.
Ablation techniques are less invasive and consequently
less morbid than surgical resection. Patients can generally
be treated as outpatients with a rapid recovery to normal
activities. Percutaneous ablation procedures can be repeated
if necessary and can be used to salvage recurrences after
resection. 5 Although chemotherapy routines are frequently
interrupted by surgical resection for 6 weeks, this same
requirement is not present with percutaneous ablation techniques.
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lization, intra-arterial chemotherapy ports, and isolated
hepatic perfusion (IHP)—are potential techniques for managing
patients with unresectable liver metastases. Understanding
the timing and role of these techniques in the
multidisciplinary care of the patient is critical. Implementation
of the IR clinic for consultation has enabled better integration
of these therapies into the patient’s overall care and has
facilitated improved opportunities for clinical studies.
In a review of nine published articles for patients treated
for unresectable colorectal liver metastases, the 5-year survival
rate varied between 14% and 55% (median 30%). For
the subgroup of patients with metastases smaller than or
equal to 4 cm, this 5-year survival rate was better at 18% to
56% (median 34%). 3 These are improved survival rates
compared with chemotherapy alone and comparable to patients
for whom metastases could be resected. 7 There has
not been a randomized study for resectable liver metastases
comparing resection with RFA. 8
“Test of Time” Approach
The “test of time” approach using percutaneous ablation
was proposed by Livraghi et al in 2003 to allow the biology
of the disease to express itself and to maintain quality of life
in patients with liver metastases from colorectal cancer. 9
The concept is that many patients may be able to avoid
unnecessary surgery by undergoing ablation of liver metastases
in the interval from the time of diagnosis of liver
metastases to the time of hepatic metastatectomy. The
theory is that RFA can completely treat many metastases
with a small local recurrence rate. Those without recurrence
will have avoided resection. In the delayed period from
diagnosis to surgery, the patient who develops innumerable
metastases would also be able to avoid unnecessary, unbeneficial
surgery. For patients with local recurrence after
ablation, there would still be an opportunity to repeat
ablation or perform resection. In summary, this approach
would allow the patient with a successful ablation and the
patient for whom surgery would not have helped because of
an early explosion of metastases to benefit by avoiding
resection. This theory has not been tested in a randomized,
controlled study but, nonetheless, offers an interesting management
concept.
Arterial Therapies
Arterial therapies for colorectal liver cancer metastases
can be performed to complement or salvage the effects of
systemic therapy. The application of a locoregional therapy
From the Memorial Sloan-Kettering Cancer Center, New York, NY.
Authors’ disclosures of potential conflicts of interest are found at the end of this article.
Address reprint requests to Stephen B. Solomon, MD, Memorial Sloan-Kettering Cancer
Center, 1275 York Ave., H-118, New York, NY; email: solomons@mskcc.org.
© 2012 by American Society of Clinical Oncology.
1092-9118/10/1-10