“We are most enthusiastic about the use of radioembolization to treat patients with early stage Barcelona Clinic Liver Cancer (BCLC) A disease. The long time to progression following segmental radioembolization allows most patients to be bridged to liver transplant following one treatment; this therapy can now be delivered on the same day as planning angiography,” write Riad Salem and Robert J Lewandowski, Chicago, USA.
We presented data at the Society of Interventional Radiology annual meeting this year on 1,000 hepatocellular carcinoma (HCC) patients treated with glass microsphere radioembolization (Therasphere, BTG) at Northwestern University in Chicago, USA. Through this large patient cohort, we report on our vast experience with radioembolization that has now become our institutional standard of care and treatment of choice for hepatocellular carcinoma.
Radioembolization was historically employed in those patients deemed unsuitable for chemoembolization; typical patients exhibited multifocal bilobar disease, infiltrating tumours, large tumours, portal vein (tumour) thrombus, elevated performance status, or significant comorbidities. Radioembolization was limited in competitiveness from a clinical adoption standpoint since it was considered only in such advanced disease compared to early disease for chemoembolization. This was our practice until 2005, when we started observing long-term benefits of Y-90: outpatient treatment, excellent response rates, better quality of life, and downstaging to resection and transplantation. A recent prospective randomised trial performed at our institution demonstrated a significantly longer time to progression after radioembolization compared to conventional chemoembolization, reinforcing the knowledge that fewer treatments are required for patients with this therapy.
We view the two recent randomised prospective trials (SARAH and SIRveNIB) positively. While these trials did not meet their primary endpoint of superiority of survival compared with sorafenib, they did bolster what we have known: radioembolization offers similar survival but improved tolerability and quality of life compared with systemic agents for patients with advanced HCC. The potential of radioembolization in advanced stage HCC is particularly evident in patients with portal vein tumour thrombus. The concept of boost radioembolization describes an aggressive use of this therapy in patients with more invasive tumour biology. Targeting tumours with doses >200 gray have yielded survival outcomes not previously seen. Combining radioembolization with systemic therapies, such as immunotherapy, offer much promise with many studies currently underway. We are most enthusiastic about the use of radioembolization to treat patients with early stage Barcelona Clinic Liver Cancer (BCLC) A disease. The long time to progression following segmental radioembolization allows most patients to be bridged to liver transplant following one treatment; this therapy can now be delivered on the same day as planning angiography. Radioembolization has also been shown to have better capacity to downsize tumours to within Milan criteria than chemoembolization, allowing more patients to be considered for liver transplantation Newer applications of radioembolization have the potential to expand the application of curative therapies for patients with unresectable disease. Radiation lobectomy, defined as lobar radioembolization with the intent to facilitate surgical resection in patients with small future liver remnant, has been compared favourably to portal vein embolization by providing hepatic tumour control during the time interval to hypertrophy while also optimizing R0 resection by shifting tumours away from major vessels. Tumour cell death prior to resection may equate to decreased dissemination of viable microscopic tumour cells during surgical mobilisation/manipulation. Radiation segmentectomy, defined as segmental radioembolization with the intent to deliver high dose, ablative radiation doses to the targeted tumour and adjacent surrounding non-tumorous parenchyma has demonstrated excellent tumour response and complete pathologic necrosis in explant specimen in patients with solitary HCC <5cm. Survival outcomes in patients with preserved liver function and small peripheral tumors compare favourably to liver resection and ablation, suggesting that radiation segmentectomy may be considered curative in these select patients.
Over the last two decades, radioembolization has helped move the field of interventional oncology forward and demonstrated tremendous versatility in treating HCC. Early disease patients can be treated with radiation segmentectomy/lobectomy as well as bridged or downstaged to transplantation. Those with vascular invasion can be treated with Y-90, providing similar survival outcomes as systemic agents with fewer side-effects. Overall, Y-90 has become one of the standards of care for HCC and an essential tool for all interventional radiologists.
Riad Salem is section chief, Interventional Radiology and vice-chair, Image-Guided Therapies, Department of Radiology, Northwestern University, Chicago, USA. He is an advisor to BTG. Robert Lewandowski is professor of Radiology, Medicine, and Surgery and director of Interventional Oncology, Department of Radiology at the same institution. He is a consultant to BTG