Interventional oncology (abbreviated IO) is a subspecialty field of interventional radiology that deals with the diagnosis and treatment of cancer and cancer-related problems using targeted minimally invasive procedures performed under image guidance. [1] [2] Interventional oncology has developed to a separate pillar of modern oncology and it employs X-ray, ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI) to help guide miniaturized instruments (e.g. biopsy needles, ablation electrodes, intravascular catheters) to allow targeted and precise treatment of solid tumours (also known as neoplasms) located in various organs of the human body, including but not limited to the liver, kidneys, lungs, and bones. [3] [4] Interventional oncology treatments are routinely carried out by interventional radiologists in appropriate settings and facilities. [5]
Interventional oncology procedures are generally divided between diagnostic procedures that help obtain tissue diagnosis of suspicious neoplasms and therapeutic ones that aim to cure or palliate the tumour. Therapeutic interventional oncology procedures may be classified further into ablation techniques that destroy neoplastic tissues by delivery of some form of heat, cryo or electromagnetic energy and embolization techniques that aim to occlude the blood vessels feeding the tumour and thereby destroy it by means of ischemia. Both ablation and embolization techniques are minimally invasive treatment, i.e. they may be delivered through the skin (in a percutaneous way) without the need for any skin incisions or other form of open surgery. Hence, most treatments are nowadays offered as day case or outpatient appointments and patients may enjoy rapid recovery and minimal pain and discomfort with low rates of complications. [6]
Uses different types of energy to burn (radiofrequency ablation (RFA) and microwave ablation (MWA)), deliver electrical fields/electroporate (irreversible electroporation(IRE)) or freeze (cryoablation) solid tumors resulting in tumor cell death. Ablation techniques can be performed throughout the body such as in the lung, [7] liver, [8] [9] kidney, [10] prostate, [11] breast, [12] bone, [13] and other organs using image guidance to place a needle/probe through the skin into the target tissue.
Uses a machine that emits high frequency sound waves to kill cancer cells and provide relief for tumor-related pain, such as in the bone.
Interventional oncology has long been used to provide palliative care for patients. IO procedures can help reduce cancer-related pain and improve patients’ quality of life. Tumours can intrude into various ducts and blood vessels of the body, obstructing the vital passage of food, blood or waste. The interventional radiological treatment known as stenting can be used to re-open blockages, for example of the esophagus or bile ducts in cases of esophageal cancer or cholangiocarcinoma, respectively, considerably relieving the patient's adverse symptoms. [22]
Interventional oncology (IO) procedures are commonly applied to treat primary or metastatic cancer. IO treatments may be also offered in combination with any of the above oncological therapies in order to augment the therapeutic outcome in more complex or widespread (metastatic) cancer cases. There is a variety of applications of interventional oncological treatments for tumors that arise in the:
While the surgical resection of tumours is generally accepted to offer the best long-term solution, it is often not possible due to the size, number or location of the tumour. IR therapies may be applied to shrink the tumour, making a surgical or interventional treatment possible. Some patient groups may also be too weak to undergo open surgery. IR treatments can be applied in these complex cases to provide effective and milder forms of treatment. Interventional oncological techniques can also be used in combination with other treatments to help increase their efficacy. For example, IO techniques can be used to shrink large tumours making them easier to excise. Chemotherapeutic drugs can also be administered intra-arterially, increasing their potency and removing the harsh effects of system-wide application.
Patients can greatly benefit from IO treatments. The minimally invasive nature of the treatments means they cause less pain, fewer side effects and shorter recovery times. Many IO procedures can be performed on an outpatient basis, freeing up hospital beds and reducing costs. [33]
Cancer is a multifaceted disease group that requires a multidisciplinary approach to treatment. Numerous studies have shown that cancer patients treated in multidisciplinary environments benefit greatly from the combined expertise. Interventional Radiologists are seen as playing a major role in multidisciplinary cancer teams where they provide innovative solutions to improve combined therapies and to treat complications. [34]
Proper patient selection is the key element for the success of any medical procedure and improper conduct can have fatal consequences. Patient selection protocols must be strictly followed before treating patients with IO procedures.
IO treatments are carried out under image guidance. For this reason practitioners must have attained solid training in radiation protection.
Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer in adults and is currently the most common cause of death in people with cirrhosis. HCC is the third leading cause of cancer-related deaths worldwide.
A bone tumor is an abnormal growth of tissue in bone, traditionally classified as noncancerous (benign) or cancerous (malignant). Cancerous bone tumors usually originate from a cancer in another part of the body such as from lung, breast, thyroid, kidney and prostate. There may be a lump, pain, or neurological signs from pressure. A bone tumor might present with a pathologic fracture. Other symptoms may include fatigue, fever, weight loss, anemia and nausea. Sometimes there are no symptoms and the tumour is found when investigating another problem.
Interventional radiology (IR) is a medical specialty that performs various minimally-invasive procedures using medical imaging guidance, such as x-ray fluoroscopy, computed tomography, magnetic resonance imaging, or ultrasound. IR performs both diagnostic and therapeutic procedures through very small incisions or body orifices. Diagnostic IR procedures are those intended to help make a diagnosis or guide further medical treatment, and include image-guided biopsy of a tumor or injection of an imaging contrast agent into a hollow structure, such as a blood vessel or a duct. By contrast, therapeutic IR procedures provide direct treatment—they include catheter-based medicine delivery, medical device placement, and angioplasty of narrowed structures.
Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin (pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially induced (therapeutic), as a hemostatic treatment for bleeding or as a treatment for some types of cancer by deliberately blocking blood vessels to starve the tumor cells.
Transcatheter arterial chemoembolization (TACE) is a minimally invasive procedure performed in interventional radiology to restrict a tumor's blood supply. Small embolic particles coated with chemotherapeutic drugs are injected selectively through a catheter into an artery directly supplying the tumor. These particles both block the blood supply and induce cytotoxicity, attacking the tumor in several ways.
Radiofrequency ablation (RFA), also called fulguration, is a medical procedure in which part of the electrical conduction system of the heart, tumor, sensory nerves or a dysfunctional tissue is ablated using the heat generated from medium frequency alternating current. RFA is generally conducted in the outpatient setting, using either a local anesthetic or twilight anesthesia. When it is delivered via catheter, it is called radiofrequency catheter ablation.
Cryoablation is a process that uses extreme cold to destroy tissue. Cryoablation is performed using hollow needles (cryoprobes) through which cooled, thermally conductive fluids are circulated. Cryoprobes are positioned adjacent to the target in such a way that the freezing process will destroy the diseased tissue. Once the probes are in place, the attached cryogenic freezing unit removes heat from ("cools") the tip of the probe and by extension from the surrounding tissues.
Electrochemotherapy (ECT) is a type of chemotherapy that allows delivery of non-permeant drugs to the cell interior. It is based on the local application of short and intense electric pulses that transiently permeabilize the cell membrane, thus allowing transport of molecules otherwise not permitted by the membrane. Applications for treatment of cutaneous and subcutaneous tumors have reached clinical use by utilizing drugs such as bleomycin or cisplatin). Electrochemotherapy with bleomycin was used to treat a patient for the first time in 1991 at the Institute Gustave Roussy in France, while electrochemotherapy with cisplatin was used to treat for the first time in 1995 at the Institute of Oncology, Ljubljana, Slovenia. Since then, more than 4000 patients were treated with electrochemotherapy all over the world. Recently, new electrochemotherapy modalities have been developed for treatment of internal tumors using surgical procedures, endoscopic routes, or percutaneous approaches to gain access to the treatment area.
A liver metastasis is a malignant tumor in the liver that has spread from another organ affected by cancer. The liver is a common site for metastatic disease because of its rich, dual blood supply. Metastatic tumors in the liver are 20 times more common than primary tumors. In 50% of all cases the primary tumor is of the gastrointestinal tract; other common sites include the breast, ovaries, bronchus and kidney. Patients with Colorectal cancer will develop liver metastases during the disease
Selective internal radiation therapy (SIRT), also known as transarterial radioembolization (TARE), radioembolization or intra-arterial microbrachytherapy is a form of radionuclide therapy used in interventional radiology to treat cancer. It is generally for selected patients with surgically unresectable cancers, especially hepatocellular carcinoma or metastasis to the liver. The treatment involves injecting tiny microspheres of radioactive material into the arteries that supply the tumor, where the spheres lodge in the small vessels of the tumor. Because this treatment combines radiotherapy with embolization, it is also called radioembolization. The chemotherapeutic analogue is called chemoembolization, of which transcatheter arterial chemoembolization (TACE) is the usual form.
Bone metastasis, or osseous metastatic disease, is a category of cancer metastases that result from primary tumor invasions into bones. Bone-originating primary tumors such as osteosarcoma, chondrosarcoma, and Ewing sarcoma are rare; the most common bone tumor is a metastasis. Bone metastases can be classified as osteolytic, osteoblastic, or both. Unlike hematologic malignancies which originate in the blood and form non-solid tumors, bone metastases generally arise from epithelial tumors and form a solid mass inside the bone. Bone metastases, especially in a state of advanced disease, can cause severe pain, characterized by a dull, constant ache with periodic spikes of incident pain.
Microwave ablation is a form of thermal ablation used in interventional radiology to treat cancer. MWA uses electromagnetic waves in the microwave energy spectrum to produce tissue-heating effects. The oscillation of polar molecules produces frictional heating, ultimately generating tissue necrosis within solid tumors. It is generally used for the treatment and/or palliation of solid tumors in patients who are nonsurgical candidate.
Irreversible electroporation or IRE is a soft tissue ablation technique using short but strong electrical fields to create permanent and hence lethal nanopores in the cell membrane, to disrupt cellular homeostasis. The resulting cell death results from induced apoptosis or necrosis induced by either membrane disruption or secondary breakdown of the membrane due to transmembrane transfer of electrolytes and adenosine triphosphate. The main use of IRE lies in tumor ablation in regions where precision and conservation of the extracellular matrix, blood flow and nerves are of importance. The first generation of IRE for clinical use, in the form of the NanoKnife System, became commercially available for research purposes in 2009, solely for the surgical ablation of soft tissue tumors. Cancerous tissue ablation via IRE appears to show significant cancer specific immunological responses which are currently being evaluated alone and in combination with cancer immunotherapy.
DFINE, Inc. was an American medical device company with headquarters in San Jose, California. It was known for its development of minimally invasive therapeutic devices built upon a radiofrequency platform for the treatment of spinal diseases. The platform included two applications, the StabiliT Vertebral Augmentation System for the treatment of vertebral compression fractures and the STAR Tumor Ablation System for pain relief treatment of metastatic spinal tumors.
Targeted radiofrequency ablation is a minimally invasive procedure to treat severe pain and discomfort caused from metastatic tumors in the vertebral body of the spine. This procedure uses radiofrequency energy to target and ablate a specific spinal tumor, causing it shrink and reduce the pressure on the surrounding nerves and tissues. The procedure minimizes damage to the vertebrae and surrounding tissues. It is used as a palliative therapy rather with the intention of treating the cancer itself.
Hepatic artery embolization, also known as trans-arterial embolization (TAE), is one of the several therapeutic methods to treat primary liver tumors or metastases to the liver. The embolization therapy can reduce the size of the tumor, and decrease the tumor's impact such its hormone production, effectively decreasing symptoms. The treatment was initially developed in the early 1970s. The several types of hepatic artery treatments are based on the observation that tumor cells get nearly all their nutrients from the hepatic artery, while the normal cells of the liver get about 70-80 percent of their nutrients and 50% their oxygen supply from the portal vein, and thus can survive with the hepatic artery effectively blocked. In practice, hepatic artery embolization occludes the blood flow to the tumors, achieving significant tumor shrinkage in over 80% of people. Shrinkage rates vary.
Combinatorial ablation and immunotherapy is an oncological treatment that combines various tumor-ablation techniques with immunotherapy treatment. Combining ablation therapy of tumors with immunotherapy enhances the immunostimulating response and has synergistic effects for curative metastatic cancer treatment. Various ablative techniques are utilized including cryoablation, radiofrequency ablation, laser ablation, photodynamic ablation, stereotactic radiation therapy, alpha-emitting radiation therapy, hyperthermia therapy, HIFU. Thus, combinatorial ablation of tumors and immunotherapy is a way of achieving an autologous, in-vivo tumor lysate vaccine and treating metastatic disease.
Radiation lobectomy is a form of radiation therapy used in interventional radiology to treat liver cancer. It is performed in patients that would be surgical candidates for resection, but cannot undergo surgery due to insufficient remaining liver tissue. It consists of injecting small radioactive beads loaded with yttrium-90 into the hepatic artery feeding the hepatic lobe in which the tumor is located. This is done with the intent of inducing growth in the contralateral hepatic lobe, not dissimilarly from portal vein embolization (PVE).
Transarterial bland embolization is a catheter-based tumor treatment of the liver. In this procedure, embolizing agents can be delivered through the tumor's feeding artery in order to completely occlude the tumor's blood supply. The anti-tumor effects are solely based on tumor ischemia and infarction of tumor tissue, as no chemotherapeutic agents are administered. The rationale for the use of bland embolization for hepatocellular carcinoma (HCC) and/or other hyper-vascular tumors is based on the fact that a normal liver receives a dual blood supply from the hepatic artery (25%) and the portal vein (75%). As the tumor grows, it becomes increasingly dependent on the hepatic artery for blood supply. Once a tumor nodule reaches a diameter of 2 cm or more, most of the blood supply is derived from the hepatic artery. Therefore, bland embolization and transarterial chemoembolization (TACE) consist of the selective angiographic occlusion of the tumor arterial blood supply with a variety of embolizing agents, with or without the precedence of local chemotherapy infusion. The occlusion by embolic particles results in tumor hypoxia and necrosis, without affecting the normal hepatic parenchyma.
Damian E. Dupuy, M.D., F.A.C.R. is an adjunct professor of Diagnostic Imaging at Brown University's Warren Alpert Medical School and Director of Ablation services at Cape Cod Hospital. He is also a Member of Cape Cod preferred Physicians.