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. 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. Interventional oncology treatments are routinely carried out by interventional radiologists in appropriate settings and facilities.
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Applications
Interventional oncology procedures are commonly applied to treat primary or metastatic cancer. Interventional oncology may be offered once traditional surgery, chemotherapy or radiotherapy have failed or are not considered safe. 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 an increase in the variety of applications of interventional oncological treatments for primary and metastatic cancer in different human body organs:
Milestones
1930 – First therapeutic embolization procedure (of a carotid-cavernous fistula); described by Brooks.
1960s – Radioisotopes such as Yttrium-90 (Y90) started to be investigated for the use in cancer treatments.
1966 – Embolization therapy to treat tumors and spinal cord vascular malformations by blocking the blood flow.
1969 – The catheter-delivered stenting technique and prototype stent.
1970s – Embolisation agents started to be used in palliative care to treat liver tumors.
1980 – Cryoablation to freeze liver tumors.
1983 – Laser interstitial thermal therapy first performed on a tumour by Bown.
1985 – Self-expanding stents are developed for vascular and oncological applications.
1990 – Radiofrequency ablation (RFA) technique for liver tumors.
1990s – Treatment of bone and kidney tumors by embolization.
1990s – RFA for soft tissue tumors, i.e., bone, breast, kidney, lung and liver cancer.
1997 – Intra-arterial delivery of tumor-killing viruses and gene therapy vectors to the liver.
1997 – HIFU first used to treat prostate cancer.
2012 – Pioneering liver chemoperfusion study reported by Delcath for disseminated liver metastases.
Procedures
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.
Diagnostic techniques
Ablation techniques
Embolisation techniques
Palliative techniques
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.
Benefits
While the surgical resection of tumours is generally accepted to offer the best long-term solution, it is often not possible due 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.
Multidisciplinary approach
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.
Patient selection
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.
Radiation protection
IO treatments are carried out under image guidance. For this reason practitioners must have attained solid training in radiation protection.