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Page 4 of 10 Naeem et al. Hepatoma Res 2018;4:18 I http://dx.doi.org/10.20517/2394-5079.2018.22

PEI may be considered as an alternate curative approach for patients with limited hepatic malignancies
who are poor surgical candidates. High local recurrence rates preclude PEI in patients with tumours
larger than 5 cm, or with a volume in excess of 30% of the total liver volume. Other contraindications
include extra-hepatic disease, involvement of the dome of the liver, portal vein thrombosis and Child-
Pugh class C cirrhosis.

Although rare, serious adverse effects associated with PEI include intra-peritoneal haemorrhage, liver
failure, bile duct necrosis or biliary fistula, portal vein thrombosis, hepatic infarction, hypotension and
renal failure . The incidence of such major complications has been found to be as low as 2.2% according to
[21]
some studies. Other minor side effects experienced more commonly include localized pain and peritoneal
irritation secondary to ethanol leakage .
[22]

THERMAL ABLATION
Thermal ablative therapies for HCC include hyper-thermic treatments like radiofrequency ablation,
microwave ablation, and laser ablation as well as cryotherapy. Hyper thermic modalities typically achieve
destruction of the tumor by exposing the tissues to cytotoxic temperatures. While hyper-thermic techniques
are mostly administered using a percutaneous approach, open or laparoscopic approach is often employed
for cryotherapy . Compared to RFA, Laser and microwave ablation have not been as well studied and are
[23]
not widely available.

RFA
By generating an alternating electric field within the tissues using a needle electrode, radiofrequency
ablation relies on ionic vibrations to generate large amounts of frictional heat, inducing temperatures in
excess of 60 C, leading to irreversible cellular damage . By producing a safety ring within the peri-tumoral
[24]
tissue, RFA is better able to achieve complete eradication of the primary lesion, as well as micro-satellites
located within its proximity. Due to the larger ablation area of up to 3 cm with each application, RFA is
also able to achieve complete eradication of the disease, requiring fewer number of electrode insertions,
when compared with PEI.

Using RFA, treatment response has been found to correlate best with the size of the lesion; a complete
response rate between 80%-90% in tumors up to 3 cm in diameter [24-27] , and 50%-70% in lesions between
3 and 5 cm in diameter [25,28-31] . Five-year survival rates following RFA were reported as 48%-71% by some
studies [32-34] . As with local tumor control, survival following RFA was also found to correlate best with the
size of the lesions. For instance, three-year survival rates for lesions > 5 cm, 2.1 to 5 cm, and ≤ 2 cm have been
reported as 59%, 74%, and 91%, respectively by a study comprising 302 patients .
[35]
When compared with PEI, significant differences have been observed particularly in terms of local control of
the disease, as evidenced by local recurrence rates of only 2%-18% following RFA, as compared to 11%-45%
in case of PEI [36-40] .

Like PEI, radiofrequency ablation is indicated in patients with early stage liver-only disease, who are
candidates for curative therapy but do not meet the resectability criteria. It has also proven efficacious in
the treatment of recurrent HCC lesions following partial hepatectomy [35,41] . It should however, be avoided
in case of lesions located in the dome or the inferior edge of the liver due to the risk of diaphragmatic
injury . It is also advisable to avoid RFA in case of sub-capsular tumors located within 1 cm of the hepatic
[42]
capsule, due to the risk of needle-track seeding, which was observed in 4 out of 32 patients in a series
[43]
[Table 1].