Transarterial embolization of non-bleeding hepatocellular adenomas: a pilot study

Hepatocellular adenoma (HCA) is the most important, albeit uncommon, benign
tumour of the liver that mostly occurs in women. A rise in incidence is seen
over the last few decades, correlated to the widespread use of oral
contraceptives. Other, less common aetiologies include use of anabolic
androgens and history of glycogen storage disease. Another cause of the
increased incidence is the expended detection by routine ultrasound, computed
tomography (CT) and magnetic resonance imaging (MRI) for other reasons. The
increasing incidence of obesity, the metabolic syndrome and steatosis might
also contribute to this increase, especially to the increased occurrence of HCA
in men.

Hepatocellular adenomas are hypervascular lesions comprised of multiple
sinusoids of dilated thin-walled capillaries with exclusively arterial blood
supply, thereby resulting in a high blood pressure within these tumours, making
it susceptible for life threatening bleeding. The risk of spontaneous bleeding,
ranging from 20-40% , increases along with the diameter of the tumour, and may
require treatment of HCAs even in absence of symptoms. Furthermore, malignant
evolvement of this benign process into hepatocellular carcinoma (HCC) may occur
in 4.3% of the patients. An established risk factor for this transformation HCC
is the size of the HCA, as malignant evolvement is rare in lesions smaller than
5 cm Also a positive *-catenin (exon 3 mutated) status of HCA is associated
with an increased chance of malignant alteration. However, performance of
biopsy of an HCA to determine its *-catenin status has not become routine,
owing to the risk of sampling error, bleeding and needle-track tumour seeding
(the latter two carrying a small risk). Only when the imaging based diagnosis
remains uncertain, biopsy will be performed. As a non-invasive diagnostic tool,
MRI has become the primary diagnostic tool in identifying HCA subtypes.

Thus far, elective surgical resection has been regarded the gold standard
treatment for patients with a HCA, as it provides long-term cure of symptoms,
eradicates the possibility of bleeding and malignant evolvement and eliminates
the option of leaving a lesion in situ that is misclassified on imaging as
being benign. Especially in the group of lesions equal to or larger than 5 cm,
resection is advised based on the aforementioned risks of spontaneous bleeding
and malignant transformation.

Elective liver resection for non-ruptured benign tumours is still associated
with a reported morbidity and mortality of up to 27% and 3%, respectively.
incontrast, our review compromising a total of 151 patients undergoing TAE
identified no mortality, no need for further surgical management, and effective
realisation of haemodynamic stability in the majority of patients receiving
TAE. Moreover, our review identified reduction in size on computed tomography
(CT) or MRI after embolisation , probably caused by the hypervascular nature of
the HCAs with its exclusive arterial blood supply. Finally, transarterial
embolisation is hypothesized to be a less invasive treatment for patients with
a HCA, of whom the majority is represented by young, otherwise healthy
individuals. Cosmetic results are known to play an important role in this group
of patients. Regarding the results of previous studies, it appears that TAE is
also an effective treatment for non-bleeding HCA , and could therefore also be
used in an elective setting to avoid unnecessary laparotomy.

It is this tumour regression in both haemorrhaging and non-haemorrhaging HCAs,
its subsequent reduction of the risk of severe haemorrhage and, consequently,
probably also malignant transformation, which supports the use of TAE as a
treatment for unruptured HCAs * 5 cm. Also, the cosmetic advantages of this
minimal invasive technique could benefit the quality of life of this group of
young female patients as compared to surgery. However, previous studies were
all non-randomised studies and case series, with a limited level of evidence.
Moreover, the effect of this procedure on patients` quality of life and the
behaviour of these tumours post-procedure in terms of size and remaining vital
tumour tissue are not completely understood due to lack of sufficient data.
Therefore, prior to investigating this technique in a larger population, a
pilot study is needed to gain insight into the effects of TAE on HCAs and their
behaviour post-embolisation.

To gain insight into the effects of TAE on HCAs and their behavior
post-embolisation.

Non-randomised pilot study

Transarterial embolisation

The extra hospitalization and the embolisation procedure might be a burden for
the patient. The procedure might be painful, as the external iliac artery is
punctured. However, adequate painkillers will be administered. The risks of the
embolisation procedure are smaller than the risks of the conventional
operation. However, a chance exists that patients will undergo both the
embolisation procedure and surgery. In this scenario the patient will have the
risk of both procedures. However, the embolisation procedure will lower the
risk of inter-operative bleeding.