The liver is one of the few areas where microwave ablation may have a better safety profile than cryoablation, particularly for tumors >4 cm, multiple tumors and patients with liver dysfunction and low platelets. However, our recent large series of liver cryoablation confirmed that if liver cryoablation is limited to patients with tumors <4 cm and platelets >100,000, the complication rate dropped to similar levels reported for heat-based liver ablations. Cryoablation may still be favored near central structures and ability to “sculpt” large enough ice to cover all tumor margins. Our renal cryoablation series have shown no greater tumor recurrence for larger tumors, unlike the greater recurrence noted for heat-based ablations.
These may be considered primary (e.g., hepatocellular carcinoma = HCC) or metastatic tumors that have spread from other primary cancers (i.e., from cancers that arose in the colon, lung, kidney, breast, pancreas, etc.). The lower recurrence rates suggested for cryoablation over microwave may not be nearly as important as the additional risk of recurrence elsewhere in the liver or lungs, etc. due to the inherent disease risk for metastatic tumors, as well as HCC. Conversely, some patients may do very well with repeat hepatic ablations. One of our patients with an unusual tumor (hemangioendothelioma – a low grade angiosarcoma) has done well for over 15 years and over 70 tumors receiving only ablation.
Usually these are solitary tumors, but depending on the size, several tumors may be treated in the same or multiple sessions.
Approximately <6 cm without evidence of extensive local spread, or likely metastases to adjacent nodes or elsewhere in the body. If the tumor is >4 cm, an additional PET/CT, liver protocol CT or MRI and/or separate chest CT may be necessary to better evaluate potential for other metastases.
Nearly any location within the liver for either microwave or cryoablation. As noted, cryoablation may have more flexibility for peripheral lesions requiring additional hydrodissection and/or balloon interposition, as well as greater safety from biliary damage for central locations.
- An exception would be if the tumor has invaded the portal vein, inferior vena cava or portions of the biliary system.
- As above, tumors that have spread to the local lymph nodes or elsewhere in the body (i.e., lungs, adrenal glands, pancreas, etc.) may require additional considerations of systemic therapy.
Similar to kidney ablations, our recent large liver cryoablation series used balloon and/or hydrodissection in up to 35% of procedures.
- Hydrodissection: if the tumor is located near adjacent stomach, small bowel or large bowel, a small catheter (5F) may be placed between the tumor and bowel for infusing saline to protect that space, thereby preventing the ablation zone (ice or heat) from proceeding into the bowel.
- Balloon interposition: rarely, when fluid is not sufficient to keep away adjacent bowel, a balloon may be placed via a different puncture site and placed through an introducing tube or sheath.