Evaluation of Trans-Arterial Chemo-Embolisation (TACE) for the Treatment of Unresectable Hepatocellular Adenoma in the Dog
Hepatocellular adenoma is a benign primary hepatic malignancy most often diagnosed as an incidental finding. Complete surgical resection is curative but by the time of diagnosis high tumour burden may make this unachievable. TACE has been used successfully as a minimally invasive palliative therapy for humans with primary hepatic neoplasia. It has also been performed experimentally in healthy dogs. We performed TACE in dogs in order to assess the technical difficulties, the occurrence and severity of toxicities, and the clinical response associated with this technique when used to treat hepatocellular adenoma.
Two dogs with unresectable, extensive hepatocellular adenoma were evaluated. Under general anaesthesia percutaneous coeliac arteriography was performed. The position of the common hepatic artery was established and it was selectively catheterized. A chemoembolic emulsion of 5 ml/m2 iodized oil radiographic contrast agent (Lipiodol) plus doxorubicin 30 mg/m2 (case 1) or 35 mg/m2 doxorubicin and 17.5 mg/m2 mitomycin C (case 2) was then infused. In case 2, arterial embolisation was also performed with polyvinyl alcohol particles (PVA-700, Cook U.K.). Tumour volume measurements obtained from CT scans were used to assess response. Measurements were obtained pre-TACE and approximately 1 and 3 months post-TACE.
In both cases selective catheterization was only achieved to the level of the common hepatic artery preventing unilateral TACE of the side affected by the tumour.
An acute anaphylactoid reaction characterised by tachycardia and a reduction in blood pressure occurred on injection of the chemoembolic mixture in case 2. This resolved with intravenous adrenaline (epinephrine). Post-TACE both dogs developed post-embolisation syndrome (PES) (vomiting, pyrexia, abdominal pain) to a mild degree. These symptoms were well controlled with antiemetics, NSAID's, and opioids which had been initiated prophylactically pre-TACE. PES resolved after 6 and 1 days respectively. Myelosuppression was not observed.
Case 1 showed a small response (89% pre-TACE volume) 1 month post-TACE. However the tumour remained unresectable. Case 2's tumour volume increased slightly (102%). At 4 and 3 months respectively, both tumours had increased markedly in volume from pre-TACE levels (case 1 186%, case 2 139%).
TACE is technically feasible in dogs but use of smaller diameter catheters may make superselective catheterization possible and improve outcome.
TACE was not a successful neoadjuvant therapy for hepatocellular adenoma in these cases as both tumours remained unresectable after treatment.
Further evaluation of the technique with increased numbers of cases and a control group is required to assess if TACE is successful as a palliative therapy in slowing growth of hepatocellular adenoma and improving life expectancy.