Liver Resection After Portal Vein Ligation / Embolization and Transection Plane Devascularization With Radio Frequency / Microwave: Pilot Study on Primary and Secondary Liver Tumors

In patients with primary or metastatic liver tumors, the only potentially curative therapeutic option is represented by hepatic resection. Nowdays extended resections can be performed with acceptable morbidity and mortality. There is no unanimous definition on the criteria of resectability and the ability to perform a more or less extensive liver resection is deferred to the expertise of the center and the surgical team. The investigators will consider a tumor resectable if the surgical procedure does not damage vital structures, the normal function of the organ is preserved and and the tumor is completely removed (R0 resection). One of the limiting factors in the execution of a liver resection, in particular if it is extended, it's represented by the future remnant liver (FRL) after hepatic resection. In cases of normal organ function an FRL of 25% is considered sufficient. In case of impaired hepatic function or a history of chemotherapy, it is considered safe if at least of 40%.

Many methods have been developed and proposed to increase the resectability in patients undergoing major liver resections. In case of bilobar tumor, a two-step approach (two-stage hepatectomy)have been proposed. This procedure implies that one of the two lobes is initially freed of disease by tumor resection or ablation. After achieving an adequate compensatory hypertrophy of the lobe freed by the tumor (usually 4-6 weeks),a contralateral liver resection can be done to treat the remnant tumor.

To increase the FRL another approach is to occlude the portal branches towards one of liver lobes. This can be done with a surgical ligation (laparotomy or laparoscopy) or radiologically, using portal embolization. The technique allows to increase from 10% to 46% of the FRL with the possibility of obtaining a resection R-0 in 70-100% of cases. It is unclear whether there is any difference between the methods of portal occlusion (ligation vs embolization). To further increase hypertrophy after portal occlusion in liver tumors occupying the right liver, some researchers proposed to embolize the portal branches of segment 4th together with the right portal vein.

The group of Regensburg has introduced a new technique in two stages for tumors of the right lobe, which combines the methods mentioned above. This two-stage approach consists in the ligation of the right portal vein associated with resection of the liver along the falciform ligament (step 1). Step 2, after a period of 9 days (median - 5-25 days), after a volumetric CT to ensure an adeguate hypertrophy of the left lateral lobe, the patient undergo a right trisectionectomy. The hypertrophy of the left lateral lobe is shown to be of 74%, higher than any other techniques of ligation or portal embolizatiol proposed in the literature.

The rationale of this technique is the complete portal devascularization of the right lobe plus segment 4 that produce a greater stimulus to hypertrophy of the left lateral segments. This occurs in less time than other methods above described and allows to reduce the timeframe between the two steps and minimizes the risk of interprocedural progression of the underlying disease (incidence of drop outs in the two-stage hepatectomy of 20% for progression disease).