Stephen B. Solomon, MD
- Chief, Interventional Radiology Service
- Director, Center for Image-Guided Interventions
Interventional radiology (IR) is an increasingly common approach to diagnosing and treating cancer. The use of image-guided interventions at Memorial Sloan-Kettering Cancer Center has grown to approximately 12,000 cases annually, and my colleagues and I are engaged in numerous multidisciplinary, image-guided clinical and research initiatives.
Interventional radiologists are physicians who use image guidance — including CT and PET scans, ultrasound, x-rays, and MRI scans — to perform minimally invasive procedures that diagnose and treat disease and provide relief from symptoms.
Thermal ablation of a tumor is among the procedures we do routinely. The technique involves placing a needle into a tumor and applying extreme heat or cold to kill the cancer while preserving surrounding healthy tissue. This has traditionally been done under CT guidance, which allows us to visualize the tumor and know where to place the needle. But the CT image can’t tell us whether we have fully destroyed a tumor.
A method that could provide real-time, image-based monitoring of tumor ablation would be a valuable tool. Memorial Sloan-Kettering is one of the only hospitals in the world with an interventional PET-CT, which is housed in our Center for Image-Guided Interventions. We’re investigating a novel, Memorial Sloan-Kettering -developed way to use PET scans to assess — while a patient is still on the table — whether we have completely ablated a tumor.
In addition to destroying tumors, thermal ablation may also help activate tumor-specific T cells (a type of immune cell). When we ablate a tumor, we create an inflammatory reaction in which these cells are recruited to clean up the dead cancer cells. In the process, the T cells have the opportunity to learn that the cancer has certain markers that they might be able to recognize in order to fight cancer that has spread to other parts of the body. Generally, though, after ablation the immune response in humans is weak and not sufficient to eradicate tumors elsewhere in the body or to prevent disease progression. However, what we’ve discovered in our research in mice is that when we give a drug called ipilimumab (Yervoy™) after tumor ablation we can boost the immune system and see a response at other sites in the animal’s body. We’re now investigating this approach with a variety of cancers and with several different drugs; and, in collaboration with colleagues on the Breast Cancer Medicine Service, we’ve begun a small clinical study in women with localized breast cancer. We are looking at applying this technique to other cancers as well.
Another area of investigation in our group involves a new ablation tool called irreversible electroporation (IRE), which does not use heat or cold to kill cancer cells. This technique uses an electrical current to punch holes in cell walls, irreversibly destroying the cells. Some organs, such as blood vessels, are not made up of just cells — there’s also a protein structure. Because IRE targets only cells, we may be able to target a tumor abutting a major blood vessel, killing the cancer cells while the vessel wall — because it’s made up of these structural proteins — remains intact.
Memorial Sloan-Kettering interventional radiologists also can treat certain liver tumors by blocking branches of the hepatic artery in a procedure called embolization. With their blood supply cut off, the tumors die. We have expanded our use of the technique to include treatments for liver cancer using beads that deliver chemotherapy or radiation directly to tumors. The beads combine the therapeutic effects of radiation or chemotherapy with those of embolization.
In light of recent advances in individualized therapy for many types of cancer, molecular profiling of tumors is vital for guiding treatment decisions. To perform the necessary studies, larger amounts of tissue are required than in the past. One of the things we do as interventional radiologists is to obtain tumor samples by doing needle biopsies. We currently have a major initiative to develop innovative ways to determine — during a needle biopsy — when we have collected enough tissue. One technology we’re in the preliminary stages of exploring is spectral analysis, which involves shining a special light on a specimen as soon as it’s removed from a patient to allow us to see whether we have enough cells in the sample.
With so much progress in the field of interventional radiology we’ve also established an Oncologic Interventional Radiology Fellowship in which fellows are exposed to the full range of interventions and which also includes time to pursue research.
These are just a few examples of the ways in which our IR group is working to enhance and improve the care we provide to patients.