Interventional oncology (IO) is an emerging subspecialty of interventional radiography that “uses image-guided procedures to enhance cancer care,” according to a recent paper published in The Oncologist.1 IO has evolved over the past decade as imaging capabilities have improved and new procedures have been developed. And now, with the most advanced imaging, it is possible to use minimally invasive techniques to treat tumors. Its role in cancer treatment has been steadily growing in importance; as that same study says, “interventional oncology can now be considered the fourth pillar of modern oncology care” (the other three being medical, surgical, and radiation).
Progress in IO has been made possible by advances in cross-sectional imaging modalities: ultrasound, magnetic resonance (MR), computed tomography (CT), and positron emission tomography (PET). As interventional radiology has made technical advances, IO has leveraged them to allow physicians to provide precision cancer treatment.1 IO has also developed in recent years as medical oncology shifts toward more patient-centered and individualized treatment approaches.2 It leverages imaging to precisely plan treatment, guide the procedure, target the tumor, and assess treatment outcome.1 IO is focused on three main areas of cancer intervention: diagnosis, therapy, and symptom palliation.1 In all cases, one major benefit is a localized effect on the tumor or a single organ in the body with minimal systemic side effects.3
IO in cancer diagnosis
“Cancer is now increasingly a ‘subclinical’ disease process often detected incidentally,” the editors of Clinical Radiology wrote in a special issue on interventional oncology.4 This earlier detection of cancers when they are smaller and at an earlier stage than ever before is thanks to current routine use of diagnostic imaging.
As precision medicine and oncology continue to evolve, it is critical to take frequent tissue samples so that practitioners can understand each cancer’s specific genetic and immune characteristics. As current biopsy protocol already requires multiple cores, as the are high throughput, and specimens are processed in multiple ways for various analyses, from genomic to protein biomarker to fluorescence in situ hybridization. Although most biopsy planning relies on anatomic imaging, IO can help guide the practitioner to specific high-interest lesions with the use of molecular imaging. This allows oncologists to assess the molecular data of the most active areas of cancer, ideally leading to more precisely targeted treatment.1
IO in oncological therapy
One of the newest and emerging applications of IO is in precisely delivering novel therapeutic agents directly into tumors, either by catheter or by direct intratumoral injection. Guided imaging has also been used to deliver viral and bacterial therapies aimed at killing cancer cells.1
IO is also used to guide tumor ablation, particularly for liver cancer patients. Cone-beam computed tomography (CBCT) is an imaging modality that provides more information than traditional 2D imaging. CBCT utilizes a rotating C-arm equipped with an X-ray source and flat panel detector around the patient. CBCT can be particularly useful in interventional oncology of the liver to destroy cancerous tissue, prepare for surgery, or for symptom palliation.
Tumor destruction follows one of two approaches: percutaneous tumor ablation or chemoembolization. In the latter, also known as intraarterial procedures, either antitumoral drugs or radioactive microspheres are injected into the hepatic arteries. One example of that is transarterial chemoembolization (TACE); the blood supply to the tumor is blocked and the antitumoral drug is injected directly into the tumor. Here, precision is critical to the ablation’s success. A recent study in CardioVascular and Interventional Radiology showed that CBCT offered “better visualization of tissues and tumors” and also resulted in a “substantial modification of treatment in a significant number of cases.” Currently, the CardioVascular and Interventional Radiological Society of Europe/Society of Interventional Radiology protocol guidelines recommend CBCT for selective TACE.2
IO in symptom palliation
Maintaining quality of life is an integral part of cancer management. IO can offer techniques including ablation of painful bone metastases, draining malignant effusions and ascites, and prevention of pathologic fractures—all of which improve patient quality of life.1
IO has been particularly useful for pain management in patients with cancer, the vast majority of whom cannot get adequate relief from pain medication and radiotherapy. Up to 90 percent of patients with cancer report pain during the disease process, and about half of patients with advanced cancer report moderate to severe pain. Neurolysis, ablation, bone and vertebral augmentation are all minimally-invasive IO techniques that have value as palliative therapies for cancer pain management. These techniques act either indirectly, in the case of regional anesthesia from neurolysis, or directly on the tumor itself by inhibiting its growth and stabilizing the lesion. In using IO to treat pain, a tailored approach is necessary, utilizing different techniques depending on tumor location and the individual case.5
The future of interventional oncology
In technical advances, hybrid MRI and X-ray fluoroscopy systems (XMRI) could be used to provide precision placement of the needle for intervention and immediate feedback of the response of the tumor with advanced analysis. Artificial intelligence and robotic technologies have been shown in early studies to have potential for increasing precision for out-of-plane needle placement and shortening overall procedure time. New 3D imaging and contrast agents, as well as the development of therapeutic ultrasound, offer potential new developments in this imaging modality for IO. Specific ultrasound agents can be used to guide biopsies of aggressive tumor areas. High-intensity focused ultrasound ablation is another emerging area.1
Over the past decade as the field of IO has developed, it has become more broadly used, with many hospitals establishing subdivisions. And in 2017, the Society of Interventional Oncology was formed. The organization provides several educational resources, including the IO University Curriculum, an online continuing medical education platform for interventional radiologists to learn the basics of oncological disease management, and hosts an annual scientific meeting to promote sharing of ideas and dialogue, with lectures, panel discussions, invited papers and selected abstracts.
According to a 2019 editorial in Radiología, IO can be readily combined with more classic oncological treatments, either substituting for them, or complementing and enhancing them.3 So far, the preponderance of evidence confirms that IO has great therapeutic potential.
- Developing a Roadmap for Interventional Oncology. The Oncologist. http://theoncologist.alphamedpress.org/content/23/10/1162.full?sid=7013f74c-bd1b-466e-aa89-3b8959e751c7 Last accessed January 30, 2019.
- Cone Beam Computed Tomography (CBCT) in the Field of Interventional Oncology of the Liver. CardioVascular and Interventional Radiology. https://www.researchgate.net/publication/280096570_Cone_Beam_Computed_Tomography_CBCT_in_the_Field_of_Interventional_Oncology_of_the_Liver Last accessed January 30, 2019.
- Interventional Oncology - Where Are We Now? - And Where We Should Head For? Radiología. https://linkinghub.elsevier.com/retrieve/pii/S2173510719300151 Last accessed January 30, 2019.
- Special Issue on Interventional Oncology. Clinical Radiology. https://linkinghub.elsevier.com/retrieve/pii/S0009926017301368 Last accessed January 30, 2019.
- Pain Management: The Rising Role of Interventional Oncology. Diagnostic and Interventional Imaging. https://www.sciencedirect.com/science/article/pii/S2211568417301730?via%3Dihub Last accessed January 30, 2019.