surgical resection is the only proven curative treatment for colorectal liver metastases , resulting in overall 5-year survival rates of around 37% [ 1 , 2 ] .
contraindications to resection include patient factors ( co - morbidities precluding resection due to an unacceptably high operative risk ) and tumour factors ( presence of extensive extra - hepatic disease , including wide - spread local recurrence and extensive para - aortic lymphadenopathy ) . for a resection to be considered
, it must be technically possible to remove tumour completely while preserving an adequate functional residual liver volume . in recent years
, the numbers of patients with colorectal metastases that are considered for hepatic resection have increased .
improvements in surgical techniques with an observed reduction in morbidity and mortality following resection have enabled a more aggressive surgical approach .
new systemic chemotherapeutic agents such as oxaliplatin and irinotecan , and biological agents such as bevacizumab and cetuximab are also available , which in addition to treating in - transit disease also have an effect on established hepatic disease . in a proportion of individuals such treatment results in down - sizing of this hepatic disease , thus enabling them to be considered for resection . when an extended hepatic resection is needed to clear disease that would leave insufficient residual liver volume , selective portal vein embolisation can be employed , which aims to increase the predicted functional residual volume , thus enabling a curative extensive resection .
radiofrequency ablation ( rfa ) is the passage of electrical current through tissues to generate heat and cause cell death . since its development in the late 1990s it has been used in the management of primary and secondary liver tumours , including colorectal liver metastases .
currently , rfa may be indicated if resection is not possible and the characteristics of the hepatic disease are favourable .
studies have shown a survival benefit of rfa compared with no treatment , but resection continues to be the gold standard , being the only modality offering long - term survival [ 2 , 5 , 6 ] .
rfa is also used in combination with liver resection to treat amenable lesions in the residual liver that would otherwise preclude resection .
we report a case of colorectal liver metastasis in whom rfa appears to have facilitated a curative hepatic resection .
post - operatively he received 6 months of adjuvant chemotherapy ( fluorouracil [ 5-fu ] and folinic acid ) .
the patient remained symptom - free during follow - up , but 4 years later an elevated carcinoemobryonic antigen measurement was recorded ( 27 g / l , normal range 010 ) .
ct and magnetic resonance imaging ( mri ) revealed a lesion involving segments v and viii of the right lobe of the liver , involving the right hepatic vein and close to the middle hepatic vein .
there was no evidence of local or extra - hepatic recurrence on colonoscopy or positron emission tomography ( pet ) scan .
intra - operative ultrasound , however , revealed the tumour to involve both the right and middle hepatic veins .
tumour clearance would therefore have necessitated an extended right hepatectomy . as the hepatic parenchymal volume of the left lateral segment and the caudate lobe ( the functional residual volume ) was inadequate to permit an extended right hepatectomy , this procedure could not be performed .
two weeks after surgery a ct scan confirmed that the rfa therapy had resulted in a large area of destruction in the right lobe of the liver .
were the disease to remain static , right portal vein embolisation was to be considered , aiming to facilitate left lateral segment hypertrophy and permit an extended right hepatectomy . follow - up cross - sectional imaging showed a 3 cm tumour around the previous rfa scar with tumour in segments v and viii , extending into segments vi and i. the tumour had occluded the right hepatic vein and encased the origin of the middle hepatic vein , with extension up to the inferior vena cava , but the left hepatic and portal veins were spared .
full staging ( pet and ct ) showed no evidence of extra - hepatic disease .
mri also showed marked right lobe atrophy and unexpectedly , left lateral lobe hypertrophy ( fig .
an extended right hemi - hepatectomy with excision of a cuff of inferior vena cava and a disc of diaphragm was carried out .
five years following liver resection he is alive with several lung metastases which have responded to chemotherapy .
his quality of life is excellent and at the age of 81 he is still running his own business .
despite adequate pre - operative imaging , intra - operative hepatic ultrasound assessment revealed this case of hepatic colorectal metastasis to be unresectable at that time . extended right hepatectomy ( right trisectionectomy ) , necessary to clear tumour involving the right and middle hepatic veins , would have left an inadequate functional residual volume .
following recovery from surgery right portal vein embolisation was planned , with the intention to cause left lateral segment hepatic hypertrophy sufficient to permit resection . follow - up cross - sectional imaging revealed surprising findings .
in addition to tumour ablation , rfa seems to have caused right portal vein occlusion and consequent left lateral lobe hypertrophy .
rfa alone appears to have inadvertently resulted in sufficient functional residual volume to permit an extended right hepatectomy .
lesions near major vessels may not be heated uniformly due to the  heat sink effect of the blood flow . to abolish this effect , inflow occlusion 
experimental models and clinical experience have shown that rfa near the portal vein with inflow occlusion can result in thermal injury to the portal vein , thrombosis and deterioration of liver function .
this effect was usually associated with inflow occlusion and cirrhosis [ 8 , 9 ] . in most cases ,
inadvertent thrombosis of intra - hepatic portal veins would be a detrimental occurrence with potential for clot propagation , hepatic impairment and portal hypertension . in this case ,
this case shows the scope of rfa in contributing to liver hypertrophy and also highlights the need for regular review by a liver surgeon in patients with liver tumours previously deemed unresectable .
 surgical resection for colorectal liver metastases may only be considered when an adequate functional residual volume can be preserved . 
 selective portal venous embolisation may be used to increase this volume , whilst chemotherapy and radiofrequency ablation ( rfa ) can be used to treat inoperable lesions . a 73-year - old man with liver metastasis proceeded to surgery , with the intention to perform a right hemi - hepatectomy . 
 unexpectedly at laparotomy , despite adequate pre - operative imaging , both the right and middle hepatic veins were involved . at that time extended right hemi - hepatectomy was contraindicated by insufficient residual volume and rfa was performed . 
 follow - up imaging revealed atrophy of the lesion . 
 significantly , there was also left lateral lobe hypertrophy sufficient to permit resection , which was performed without complication . 
 thrombosis of intra - hepatic portal veins is a recognised complication of rfa but here it appears to have been beneficial . 
 the case highlights the need for regular review of unresectable hepatic disease by a liver surgeon and could suggest new modalities of portal embolisation . 
Introduction
Case Report
Discussion