We are amidst a very exciting time in oncology. Advances in chemotherapy have been nothing short of phenomenal, and new surgical techniques are allowing more and more patients to be safe resection candidates. But one of the most exciting advances in oncology has been the emergence and progression of minimally invasive targeted tumor therapies, especially those performed by Interventional Radiologists (IRs).
These technologically advanced treatments propel cancer therapy into a whole new dimension, particularly involving malignant liver tumors. IRs can combine clinical and technical expertise with advances in technology to obtain high level tumor responses safely, quickly, and effectively. The result: patients are living longer, have a better quality of life, and are happier.
Image guided, minimally invasive targeted tumor therapy now plays a fundamental role in the treatment process of many cancer patients. Nowhere in the body does this hold true more than the liver. As the incidence of both primary and metastatic liver tumors continues to grow, so does our ability to treat patients who otherwise would not have options for longer-term survival and good quality of life.
One of the most promising new, targeted liver therapies is yttrium-90 radioembolization. Currently in practice at St. Joseph’s Hospital in Tampa, this procedure employs the use of very selective angiography, requires minimal sedation, and is performed on an outpatient basis. A tiny catheter, called a microcatheter, is advanced under fluoroscopic guidance into the hepatic arteries that are feeding the tumor.
The treatment takes advantage of the fact that all liver tumors are supplied exclusively by the hepatic artery, whereas normal liver is supplied mainly by the portal vein. This fundamental provides IRs with the proverbial ‘silver bullet’: a therapy that provides an extremely intense tumor ablative dose, while essentially uneffecting normal liver tissue.
Once the microcatheter is advanced into the target vessel, millions of microscopic spheres coated with yttrium-90, a beta emitter, are infused through the catheter and lodged in the tumor capillary bed. The range of activity of the yttrium-90 is on the order of a millimeter, so the tumor gets intensely radiated and the remaining liver is mostly unharmed.
This therapy works well for every liver tumor, independent of relative radiosensitivity, due to the profound radiation dose the tumor receives. Yttrium-90 radioembolization has been proven to be effective as first line therapy or in patients with failed first, second or multiple lines of chemotherapy; prolonging survival with minimal impact on patient quality-of-life.
The procedure is very safe, with low risks of cholecystitis (1%), gastroduodenal ulcer formation (3%), radiation pneumonitis, and liver failure (both much less than 1%).
A very unique aspect of our practice is that we are one of the very select few groups in the state with an Interventional Radiology authorized user (AU); there are only a handful of IRs to have been given AU status in the state of Florida. This status is designated by the state of Florida to prescribe and administer the yttrium therapy, based on very specific and rigorous training requirements.
Although the angiography portion of the procedure must be performed by interventional radiologist, the actual dosing, dose administration and clinical evaluation for radiotherapy has been traditionally performed by non-IR physicians unfamiliar with angiography/embolization techniques and specific patient evaluation and follow up relative to these procedures. Having an IR AU helps provide a unique, comprehensive approach to patient care.
This provides unprecedented continuity, with the interventional radiologist performing the full clinical evaluation, dosing, dose calculations, and entire procedure. We strongly believe that this translates into better continuity of care, higher patient satisfaction, improved follow up, and overall better outcomes.
But IRs don’t just have one arrow in the quiver; we can target many other tumors in the body. We employ numerous additional technologies, combined with our expertise with image guided procedures, to further target tumors, including thermal and electrical ablation devices: cryoablation, radiofrequency ablation/microwave ablation, and irreversible electroporation.
Virtually all liver tumors can be treated using IR methods, and we often employ a combination of therapies for optimal outcomes. Some of our most recent and exciting discoveries in IR have shown synergistic effects of combining thermal ablation with embolization, significantly expanding tumor ablation zones and tumor cell kill rates by reducing what we call the ‘tumor vascularity heat sink’ effect.
IRs also work very closely with other specialties to facilitate tumor therapies. We are now able to augment liver cancer surgery by converting patients, who otherwise would be unresectable, to surgical resection candidates.
In order for a liver tumor patient to be resectable, they must have enough normal liver left after surgery to survive. We can now increase the amount of residual normal liver (called the ‘future liver remnant’) by ablating the segments/lobe of the diseased liver using portal vein embolization or supratherapeutic Yttrium-90 radioembolization.
These techniques cause atrophy of the diseased liver, and induce profound hypertrophy of the normal liver. For example, we have seen the lateral left lobe of the liver hypertrophy from 15% (not enough residual viable liver) to 40% (enough normal liver to survive after extended right and middle hepatic resection). We look forward to further collaboration with surgery to facilitate tumor resection, as this technique is very promising.
IRs love what we do, and for many of us interventional oncology is at the top of the list. We thoroughly enjoy collaborating with medical oncologists, surgical oncologists, and radiation oncologists to offer individualized oncologic patient care that improves survival, decreases morbidity, improves quality of life, and enhances the overall patient experience. But most of all, we love our patients and their families; with the opportunity to be a part of their most crucial time in life.
By Brian Montague, MD
Brian Montague, M.D. is an interventional radiologist at St. Joseph’s Hospital in Tampa and is part of experienced radiology team that includes Troy Woeste, M.D., Matthew Berlet, M.D., Peter Bernstein, M.D., Kelly VanEpps, M.D. and Glenn Stambo, M.D. In addition to numerous cancer therapies, other procedures performed by this highly specialized team include arterial and venous angioplasty/stenting, uterine fibroid embolization, varicose vein ablation, peripheral vascular disease treatment, hemodialysis intervention, stroke intervention and more. For additional information please visit Stjosephsir.org.