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Minimally invasive image-guided therapy for inoperable hepatocellular carcinoma

Curator & Reporter: Dror Nir, PhD

Large organs like the liver are good candidates for focused treatment. The following paper:

Minimally invasive image-guided therapy for inoperable hepatocellular carcinoma: What is the evidence today?

By Beatrijs A. Seinstra1, et. al. published mid-2010, gives a review of the state-of-the-art of the then available methods for local lesions’ ablation. As far as ablation techniques availability, I have found this review very much relevant to today’s technological reality. It is worthwhile noting that in the last couple of years, new imaging-based navigation and guidance applications were introduced into the market holding a promise to improve the accuracy of administrating such treatment. These are subject to clinical validation in large clinical studies.  From the above mentioned publication I have chosen to highlight the parts discussing the importance of imaging-based guidance to the effective application of localized ablation-type therapies.

The clinical need:

Hepatocellular carcinoma (HCC) is a primary malignant tumor of the liver that accounts for an important health problem worldwide. Primary liver cancer is the sixth most common cancer worldwide with an incidence of 626,000 patients a year, and the third most common cause of cancer-related death [1]. Only 10–15% of HCC patients are suitable candidates for hepatic resection and liver transplantation due to the advanced stage of the disease at time of diagnosis and shortage of donors.

Immerging solution:

In order to provide therapeutic options for patients with inoperable HCC, several minimally invasive image-guided therapies for locoregional treatment have been developed. HCC has a tendency to remain confined to the liver until the disease has advanced, making these treatments particularly attractive.

Minimally invasive image-guided therapies can be divided into the group of the tumor ablative techniques or the group of image-guided catheter-based techniques. Tumor ablative techniques are either based on thermal tumor destruction, as in radiofrequency ablation (RFA), cryoablation, microwave ablation, laser ablation and high-intensity focused ultrasound (HIFU), or chemical tumor destruction, as in percutaneous ethanol injection (PEI). These techniques are mostly used for early stage disease. Image-guided catheter-based techniques rely on intra-arterial delivery of embolic, chemoembolic, or radioembolic agents [22]. These techniques enable treatment of large lesions or whole liver treatment, and are as such used for intermediate stage HCC (Figure 1).

Minimally invasive image-guided ablation techniques and intra-arterial interventions may prolong survival, spare more functioning liver tissue in comparison to surgical resection (which can be very important in cirrhotic patients), allow retreatment if necessary, and may be an effective bridge to transplantation [2327].

During the last 2 decades, minimally invasive image-guided therapies have revolutionized the management of inoperable HCC.

The value of image guidance

Accurate imaging is of great importance during minimally invasive loco-regional therapies to efficiently guide and monitor the treatment. It enables proper placement of instruments, like the probe in case of ablation or the catheter in case of intra-arterial therapy, and accurate monitoring of the progression of the necrotic zone during ablation.

can all be employed. In current clinical practice, placement of the catheter in intra-arterial procedures is usually performed under fluoroscopic guidance, while ablation may be guided by ultrasound, CT or MRI.

  • Ultrasound guidance allows probe insertion from every angle, offers real time visualization and correction for motion artifacts when targeting the tumor, and is low cost. However, the gas created during ablation (or ice in the case of cryoablation) hampers penetration of the ultrasound beams in tissue, causing acoustic shadowing and obscuring image details like the delineation between tumor borders and ablation zone.
  • CT is also frequently used to guide minimally invasive ablation therapy, and is a reliable modality to confirm treatment results. In comparison to US, it provides increased lesion discrimination, a more reliable depiction of ablated/non-ablated interfaces, and a better correlation to pathologic size [28]. However, due to its hypervascularity, small HCCs can only be clearly visualized in the arterial phase for a short period of time. Another disadvantage of CT is the exposure of the patient and physician to ionizing radiation.
  • Combining US imaging for probe placement and CT for ablation monitoring reduces this exposure. At the moment, hybrid systems are being developed, enabling combination of imaging techniques, like ultrasound and CT imaging, thereby improving the registration accuracy during treatment [29]. The interest in MRI-guided ablation is growing, as it produces a high-quality image allowing high-sensitivity tumor detection and accurate identification of the target region with multiplanar imaging.
  • MRI also enables real-time monitoring of the temperature evolution during treatment [3035]. However, MRI is an expensive technique, and MRI-guided ablation is still limited in clinical practice. Currently, the most widely used ablation technique for percutaneous treatment of focal hepatic malignancies is radiofrequency ablation (RFA), which has been shown to be safe and effective for the treatment of early stage HCC [4850]. During RFA, a small electrode is placed within the tumor, and a high-frequency alternating electric current (approximately 400 MHz) is generated, causing ionic agitation within the tissue. ….. Most frequently ultrasound is used for image guidance (Figs. 23), but there are reports of groups who use CT, MRI, or fluoroscopic imaging.
Ultrasound guided RFA. a: HCC lesion in a non-surgical patient pre-treatment (pointed out by arrow). b: Just after start treatment, electrode placed centrally in the tumor. c: Gas formation during ablation causes acoustic shadowing

Ultrasound guided RFA. a: HCC lesion in a non-surgical patient pre-treatment (pointed out by arrow). b: Just after start treatment, electrode placed centrally in the tumor. c: Gas formation during ablation causes acoustic shadowing

Contrast-enhanced CT pre- and post-RFA. Same patient as in Fig. 2. a: Hypervascular lesion (biopsy proven HCC) in right liver lobe (pointed out by arrow) before treatment. b: Ablated lesion directly post ablation, with reactive hyperemia around the RFA lesion

Contrast-enhanced CT pre- and post-RFA. Same patient as in Fig. 2. a: Hypervascular lesion (biopsy proven HCC) in right liver lobe (pointed out by arrow) before treatment. b: Ablated lesion directly post ablation, with reactive hyperemia around the RFA lesion

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Other research papers related to the management of Prostate cancer were published on this Scientific Web site:

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Harnessing Personalized Medicine for Cancer Management, Prospects of Prevention and Cure: Opinions of Cancer Scientific Leaders @ http://pharmaceuticalintelligence.com

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Reporter and Curator: Ritu Saxena, PhD

Magnetic Resonance Imaging (MRI) is increasingly used in clinical diagnostics, for a rapidly growing number of indications. The MRI technique is non-invasive and can provide information on the anatomy, function and metabolism of tissues in vivo (Strijkers GJ, et al, Anticancer Agents Med Chem, May 2007;7(3):291-305). Basic contrast in the MRI image scans is as a result of contrast generated by differences in the relaxation times between different regions. Since the intrinsic contrast generated between regions is limited to allow clear and specific diagnosis, MRI contrast agents administered intravenously are increasingly being used to alter image contrast.

Gadoxetic acid, a gadolinium-based compound, is a recently developed hepatobiliary-specific contrast material for MRI that has high sensitivity in the detection of malignant liver tumors. Its salt, gadoxetate disodium, is marketed as Primovist in Europe and Eovist in the United States by Bayer HealthCare Pharmaceuticals. Gadoxetic acid is taken up by hepatocytes and then excreted into the bile ducts (Schuhmann-Giampieri G, et al, Radiology, Apr 1992;183(1):59-64). Therefore, hepatic focal lesions without normal hepatobiliary function are depicted as hypointense areas compared with the well-enhanced hyperintense background liver in the hepatobiliary phase of gadoxetic acid–enhanced MR imaging. In addition, gadoxetic acid can be used in the same way as gadopentetate dimeglumine to evaluate the hemodynamics of hepatic lesions in the dynamic phase after an intravenous bolus injection (Kitao A, et al, Radiology, Sep 2010;256(3):817-26).

Recently, researchers from Kanazawa University Graduate School of Medical Science, (Kanazawa, Japan) analyzed the correlation among biologic features, tumor marker production, and signal intensity at gadoxetic acid-enhanced MR imaging in hepatocellular carcinomas (HCCs). The findings were published in Radiology journal. The research was supported in part by a Grant-in-Aid for Scientific Research (21591549) from the Ministry of Education, Culture, Sports, Science and Technology; and by Health and Labor Sciences Research Grants for “Development of novel molecular markers and imaging modalities for earlier diagnosis of hepatocellular carcinoma.”

Research significance: HCC is the most frequent primary malignant tumor of liver and is the third most common cause of cancer death worldwide. It is the most Hepatocellular.

The accurate detection and characterization of HCC focal lesions is crucial for improving prognosis of patients with HCC.

Research problem: Gadoxetic acid–enhanced MR imaging is highly accurate for diagnosing HCC lesions. As discussed earlier, in this imaging process, hepatic focal lesions without normal hepatobiliary are hypointense as compared with the well-enhanced hyperintense background liver. However, approximately 6%–15% of hypervascular HCCs demonstrate isointensity or hyperintensity (Kitao A, et al, Eur Radiol, Oct 2011;21(10):2056-66).

Hypothesis: The reason for hyperintensity in some HCC lesions was previously shown to be due to overexpression of organic anion transporting polypeptide 8 (OATP8) (Kitao A, et al, Radiology, Sep 2010;256(3):817-26). The authors speculated that there might be a correlation of the tumor marker production and signal intensity (SI) on hepatobiliary phase images, which would reflect distinct genomic and proteomic expression of HCC. Thus, authors stated that “the purpose of this study was to analyze the correlation among the pathologic and biologic features, tumor marker production, with signal intensity (SI) on hepatobiliary phase gadoxetic acid–enhanced MR images of HCC” (Kitao A, et al, Radiology, Dec 2012;265(3):780-9).

Experimental design: From April 2008 to September 2011, 180 surgically resected HCCs in 180 patients (age, 65.0 years ± 10.3 [range, 34–83 years]; 138 men, 42 women) were classified as either hypointense (n = 158) or hyperintense (n = 22) compared with the signal intensity of the background liver on hepatobiliary phase gadoxetic acid–enhanced MR images (Abstract of the study).

Pathologic features were analyzed.

Serum analysis and immunohistochemical staining was performed and following were compared:

  1. Alpha fetoprotein (AFP) – is a main tumor marker of HCCs. AFP is the most abundant plasma protein found in the human fetus and plasma levels decrease rapidly after birth. A level above 500 nanograms/milliliter of AFP in adults can be indicative of hepatocellular carcinoma, germ cell tumors, and metastatic cancers of the liver.
  2. Absence of protein induced by vitamin K or antagonist-II (PIVKA-II) – is a clinically important serum tumor marker. PIVKAII is an incomplete coagulation factor prothrombin II whose production is related to the absence of vitamin K or the presence of the antagonist of vitamin K, which is the cofactor of g carboxylase that converts precursor into prothrombin.

Serum levels of both AFP and PIVKA-II correlate with HCC malignancy and prognosis (Miyaaki H, et al, J Gastroenterol, Dec 2007;42(12):962-8).

Results: The hyperintense HCCs showed significantly higher differentiation grade than the hypointense HCCs (P = .028). There was a significant difference in the proliferation pattern between the hypointense and hyperintense HCCs (P < .001) and the hyperintense HCCs showed a significantly lower rate of portal vein invasion than that of hypointense HCCs (P = .039). The serum levels of tumor markers AFP, AFP-L3, and PIVKA-II were significantly lower in the patients with hyperintense HCCs than in those with

hypointense HCCs (P = .003, .004, and .026). In addition, immunohistochemical analysis revealed that the expression of FP and PIVKA-II was lower in hyperintense than in hypointense HCCs (both P < .001). Also, hyperintense HCCs showed lower recurrence rate than hypointense HCCs (P = .039).

Conclusion: Variation was observed within differently stained lesions of HCC in the hepatobiliary phase gadoxetic acid–enhanced MR images as evident in tumor marker expression, proliferation pattern, differentiation grade, immunohistochemical analysis and recurrence.  The results lead to the hypothesis that hyperintense HCCs in the hepatobiliary phase gadoxetic acid–enhanced MR images might represent a particular type of HCC that is hypervascular and biologically less aggressive as compared to hypovascular HCCs. Interestingly, this research is another great example where tumor heterogeneity has been brought to light (similar to genetic heterogeneity in triple negative breast cancer deciphered by Lehmann BD, et al, 2011). The heterogeneity might be the basis of answers to why a particular therapy fails in a certain tumor type and fortifying evidence for appropriate analysis of the tumor for obtaining the desired tumor response from a particular drug.

Reference:

Kitao A, et al, Radiology, Dec 2012;265(3):780-9

Strijkers GJ, et al, Anticancer Agents Med Chem, May 2007;7(3):291-305

Schuhmann-Giampieri G, et al, Radiology, Apr 1992;183(1):59-64

Kitao A, et al, Radiology, Sep 2010;256(3):817-26

Kitao A, et al, Eur Radiol, Oct 2011;21(10):2056-66

Kitao A, et al, Radiology, Sep 2010;256(3):817-26

Miyaaki H, et al, J Gastroenterol, Dec 2007;42(12):962-8

Lehmann BD, et al, J Clin Invest, 2011;121(7):2750–2767

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