Prior to joining Vanderbilt, Dan Brown, MD, was chief of Interventional Radiology and professor of Radiology at Thomas Jefferson University Hospital in Philadelphia. Brown is a graduate of Hahnemann Medical College, now Drexel University College of Medicine. He completed a residency program in radiology at Bryn Mawr Hospital and completed a fellowship in Interventional Radiology at Pennsylvania State University. He practiced at Washington University in St. Louis for nine years before moving to Thomas Jefferson.
OBTN: What is interventional oncology and how does it fit in with the current cancer treatment paradigm?
Dr. Brown: Interventional oncology uses imageguided technology to directly target solid tumors. It’s a complementary intervention that I hope will eventually be integrated into standard care algorithms. It gives clinicians another focused area of cancer care in which we can collaborate with other specialists. We perform targeted procedures that can be characterized as either arterial or ablative. Interventional oncology, and to some extent interventional radiology, also involves the use of biopsies for genomics analysis, in a similar way as other oncologic specialists use biopsies to help guide their biological therapies or systemic therapies.
Which patients are likely candidates for interventional oncology and how are they identified?
Vanderbilt is the second place in the country to have a formal division of interventional oncology and a backbone of our program is tumor boards. I participate in at least three tumor boards a week involving specialists in gastrointestinal oncology, liver transplantation, and neuroendocrine tumors. The cornerstone tumor for interventional oncology is probably hepatocellular carcinoma. Chemoembolization is one of the older procedures that we perform dating back to 1980. And it became standard of care because, quite frankly, there was nothing else for years that did anything. Now we perform it very frequently. We see this in the transplant population or potential transplant population— we want to prevent patients from progressing beyond Milan criteria or to try to downstage patients back to Milan criteria if they’re beyond it. In patients with colorectal cancer, we can either try to get a patient to surgery with portal vein embolization or we will perform radioembolization of liver metastases or ablation of liver metastases based on where they stand with their chemotherapy. If patients get toxicity from chemotherapy, particularly neurotoxicity after FOLFOX, and have residual liver disease, sometimes we treat them to give them time off of systemic therapy. We treat a lot of patients with neuroendocrine tumors here at Vanderbilt. We perform radioembolization and bland embolization for those patients. For patients with hepatocellular and colorectal metastases, our first goal is to get them to surgery, either transplant or resection, as these treatments are potentially curative.
Can you discuss in detail some of the procedures involved with interventional oncology?
There are two main techniques that we perform—arterial interventions and ablation. For liver cancer, arterial treatment involves threading a catheter through the femoral artery to reach the primary tumor. The strategy is to use the tumor’s vasculature to deliver microscopic beads that contain radioactive materials or chemotherapy into the tumor. The beads leach out the chemotherapy over the course of several weeks. We can also infuse radioembolics in a similar way. There are two devices available—one is made of glass and the other is made of resin. In our practice, we’re treating more and more people with the radioembolic treatment because it’s an outpatient procedure. We’re starting to accumulate more data using the radioembolic treatment, especially for colon cancer and neuroendocrine tumors. Radiofrequency ablation involves delivering an electrode into a tumor and passing a current through it. This raises the temperature in the tumor to about 60° Celsius, and kills it. Microwave ablation is a newer method used to destroy tumors with heat. It’s much more powerful, but its use is not as widespread. Finally, we can freeze tumors with Cryoablation: this method will destroy tumor cells or regular noncancerous cells as well. Cryoablation is favored in small kidney masses, because the clinician can see the ice ball when it’s created. This has been very successful, and causes less pain than ablation that uses heat. And all these ablation types can be used in the kidney.
What are some of the treatments and products used in interventional oncology that are approved by the FDA?
We’ve seen a shift toward more radioembolization use. One product approved for treating hepatocellular carcinoma is TheraSphere, an FDA approved microsphere agent. SirSpheres are FDA approved for use in colorectal cancer with adjuvant chemotherapy. There are a number of prospective randomized trials going on worldwide that combine its use with first- and second-line chemotherapy regimens, and some of the first of those is called SIRFLOX. The study is designed to evaluate whether FOLFOX chemotherapy in combination with Selective Internal Radiation Therapy is more effective than chemotherapy alone. That should have data coming out some time next spring, when the data are mature enough to start analyzing.
