Interventional oncology
Interventional oncology 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 or magnetic resonance imaging to help guide miniaturized instruments to allow targeted and precise treatment of solid tumours 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.
Procedures Performed
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 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
- Fine needle aspiration: biopsy with a fine needle trying to obtain tissue diagnosis by examining the tumour cells.
- Core needle biopsy: similar to fine needle aspiration, only involving the use of larger needles to excise the tissue.
- Vacuum assisted biopsy: similar to core needle aspiration but using vacuum assistance to gather the sample. Vacuum assisted breast biopsy may provide a high diagnostic yield in case of breast tumours.
Image guided ablation
- Chemical Ablation: one of the earliest ablative techniques involving the injection of substances such as ethanol or acetic acid into a tumour to cause protein denaturation and cell death.
- Radiofrequency ablation: tissue destruction through delivery of electricity that produces ionic friction.
- *Radiofrequency ablation video demonstration: https://www.youtube.com/watch?v=8Xu0mxkLSzE
- Irreversible electroporation: delivery of electrical fields to disrupt cellular membranes and cause cell death or apoptosis or enhance targeted drug delivery.
- *Irreversible electroporation video demonstration: https://www.youtube.com/watch?v=NL-IIq-c3Ic
- Cryoablation: instant cell death by tissue freezing to temperatures as low as -20 Celsius.
- *Cryoablation video demonstration: https://www.youtube.com/watch?v=goLRh3UX0vM
- Microwave ablation: electromagnetic energy produces high frequency oscillation of water molecules leading to tissue coagulation by heat.
- *Microwave ablation video demonstration: https://www.youtube.com/watch?v=uPcU7HFumIk
- High-intensity focused ultrasound : targeted beam of focused ultrasonic waves that accumulates high energy and burns the tissue.
- Laser ablation : tissue coagulation by a laser beam.
High Intensity Focused Ultrasound
Embolisation techniques
- Transarterial embolization / Bland embolization: Injection of embolic material through a catheter into the arteries feeding a tumor in order to completely occlude the tumor’s blood supply and cause cell death. The most common indication is for treatment of unresectable liver cancer.
- Transarterial chemoembolization : Injection of a chemotherapy agent often with microparticles through a catheter into arteries feeding a tumor that both delivers chemotherapy and blocks the blood supply to the tumor to cause cell death
- *Can be performed in different ways:
- **Conventional transarterial chemoembolization : Injection of lipiodol with high dose chemotherapy with or without microparticles directly into the tumor-feeding arteries.
- **Drug eluting bead chemoembolization : delivery of microparticles that are themselves loaded with the chemotherapy agent – typically doxorubicin or irinotecan.
- Selective internal radiation therapy : Injection of small beads loaded with a radioactive isotope, Yittrium-90, into blood vessels feeding a tumor in order to deliver a lethal dose of radiation causing cell death. Can be performed in a segmental or a lobar fashion. Radiation lobectomy is commonly performed with the goal of inducing growth of the non-diseased lobe in order to have adequate liver function necessary to undergo surgical resection.
- *Y-90 video demonstration: https://www.youtube.com/watch?v=YndyQkSZl5I
- Intra-arterial chemotherapy: high dose chemotherapy is administered directly into the tumor-feeding arteries.
- Portal vein embolization : delivery of embolic material into the portal vein feeding the lobe of liver containing the tumor of interest to induce growth of the non-diseased lobe in order to have adequate liver function necessary to undergo surgical resection of lobe containing the tumor.
Palliative techniques
Diseases Treated
Interventional oncology 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 cancer cases. There is a variety of applications of interventional oncological treatments for tumors that arise in the:- Liver cancer: primary liver tumors such as hepatocellular carcinoma or cholangiocarcinoma and liver metastases are often treated by procedures such as transarterial chemoembolization, Selective internal radiation therapy, portal vein embolization, transarterial/bland embolization, or image guided ablation.
- Lung cancer: lung metastases or inoperable primary lung cancer can be treated by interventional radiology procedures such as image guided ablation.
- * Cryoablation of lung cancer video demonstration: https://www.youtube.com/watch?v=RH4po_14mDY
- Kidney cancer: kidney tumors such as renal cell carcinoma can be treated with image guided ablation with similar results to partial nephrectomy. Benign kidney tumors such as angiomyolipomas can be treated with transarterial embolization to shrink the tumor size and reduce the risk of rupture/bleeding. Other embolizations are also performed for symptom relief or prior to surgery to reduce bleeding.
- Bone Cancer: bone metastases located in the spine, pelvis and long bones can be treated with image guided ablative techniques with or without injection of cement to stabilize the bone. These treatments may be palliatively for bone metastases pain or for some cases such as osteoid osteoma can curatively treat tumors. Embolizations are also performed for prior to surgery to reduce bleeding.
- Breast Cancer: for small, solitary breast cancer image guided ablative techniques are used to treat tumors, however their efficacy versus surgical resection has not yet been studied.
- Prostate cancer: inoperable tumors can be treated with image guided ablative techniques and more recently irreversible electroporation.
- *Irreversible electroporation video demonstration: https://www.mskcc.org/videos/irreversible-electroporation-nanoknife-treat-prostate-tumors
- Pancreatic cancer: inoperable, or borderline resectable, locally advanced pancreatic adenocarcinoma can be treated with irreversible electroporation
Milestones
- 1930 – First therapeutic embolization procedure ; described by Brooks.
- 1960s – Radioisotopes such as Yttrium-90 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 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.
Benefits
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.