KW seminar: Interventional Oncology Flashcards
In the lecture is discussed that when a patient that has been treated for rectal cancer has metastasis to the liver, that first the board discusses the options of surgery. What is something to take into consideration?
The location of the metastasis. If it’s on the edge of the liver, a small part of the liver can be resected. But if the metastasis is located deeper in the liver, a whole piece of the liver needs to be resected and if this is the case you also need to look at the fact if the tumor also comprises blood vessels etc. (invasion). So then other options are possible as well.
In the lecture is discussed that when a patient that has been treated for rectal cancer has metastasis to the liver, that first the board discusses the options of radiotherapy. What is something to take into consideration?
That with radiotherapy a large part of the liver needs to be irradiated. But also surrounding organs can be irradiated as a consequence. So radiotherapy is an option, but there are risk to this.
In the lecture is discussed that when a patient that has been treated for rectal cancer has metastasis to the liver, that first the board discusses the options of chemotherapy. What is something to take into consideration?
Chemotherapy works best if there are multiple lesions in the body. But treating a single metastasis with systemic chemotherapy…
Doctors distinguish patients that still have a full care possible and patients that need palliative care. Here the old situation was that if a patient had full cure possible, the cancer could be resected. If the cancer had spread, then radiotherapy was needed. And when these metastasizing lesions are invasive, chemotherapy is offered. What has changed in the new situation?
See picture.
Name two types of treatments that belong in the category interventional oncology.
Needle-guided ablation and catheter-guided ablation.
What (in short) is needle-guided ablation?
Use of radiology imaging techniques to guide a needle with a probe into the tumor, the tumor can then be destroyed by several techniques (percutaneous ethanl injection, radiofrequence ablation, cryoablation etc.)
What (in short) is cathether-guided ablation?
Via the arm or via the groin you go into blood vessels and into the blood vessels within the liver (or other organ that has a tumor). Here, the cathether is placed into the vessel that supplies the tumor with nutrients and oxygen and beads are then injected into this vessel. These beads are either radioactive or loaded with chemotherapy.
Explain in short the general mechanism, indications (for what tumor) and complications for cryoablation?
- General: Cryoablation means freezing the tumor so that there’s irreversible damage of cancer cells.
- Indications: kidney, prostate, bone, liver (liver is fairly dangerous due to freezing/cracking of healthy parts)
- Complications: hemmorrhage due to rupture, liver abscess due to biliary injury and with large tumors there’s a risk for cryoshock syndrome.
What is radiofrequency ablation (RFA)?
Electrodes are placed within a tumor. The electrodes are connected to a machine, there are also grounding pads on thighs to complete the circle. The alternating current creates friction between ions, which creates heat. If the temperature rises between 50-100 degrees, tumor coagulation occurs.
For radiofrequency ablation (FRA) electrodes are used that either are non-expandable or expandable. The type of electrodes affects the shape of the ablation zone. How?
Non-expandable electrodes have an oval ablation zone. Expandable electrodes (umbrella) have a spherical ablation zone. (Note that the non-expandable electrodes are not very practical, since the shape of the ablation one is much smaller compared to the expandable electrodes).
What two ways are their to apply electrodes?
Electrodes can be placed on the tumor during surgery, it can be done laparoscopically or placed percutaneous where it is ultrasound guided.
What is the heat sink effect in radiofrequency ablation?
So radiofrequence ablation therapy works through a needle that heats up the tumor which results in tumor coagulation. The heat sink effect occurs when a tumor coagulates through the use of electrodes and heat. But if a blood vessel is near the tumor, the temperature of the blood (37 degrees) will slow and cool down the process of coagulation near the area of the blood vessel. So the heat sink effect reshapes the ablation zone.
What factors influence the recurrence rate?
- Regional or distant tumor
- Size of tumor
- Approach (open, laparoscopic, percutaneous)
- Proximity of vessels (heat sink effect)
What is microwave ablation (MWA)?
Probe/electrode is placed on tumor, microwaves are generated that travel through this electrode and can coagulate a tumor of <5 cm within minutes.
Why is microwave ablation more effective than radiofrequency ablation?
Microwave ablation generates active heat and therefore is more specific (blood vessels don’t affect the heat but blood vessels van be affected by the high heat (>100 degrees))
When is microwave ablation not used?
When a biliary duct is close to the tumor
What is Laser Induced Thermotherapy used for mostly and why at the same time is this therapy not used frequently anymore?
It is mostly used for superficial cancer in e.g. head and neck area. But since you need to use a lot of electrodes and the ablation zone is still small, it isn’t used very frequently anymore.
What is High-Intensity Focused Ultrasound (HIFU)?
Patients goes into a MRI. Here, a transducer in the MRI produces converging ultrasound-bundles which heat up focal spot (ablation zone).
For what cancers is High-Intensity Focused Ultrasound (HIFU) mostly used? And for what cancer can it not be used for?
It is mostly used for prostate cancer, tumors in the pelvic area and deep seeded tumors in the liver. It doesn’t work in the lungs, due to the air in the lungs (air blocks the incoming bundles of heat that are ultrasound led).
What is Percutaneous Alcoholablation (PEI)?
A side hole needle is percutaneous ultrasound or CT-guided into the tumor. Here, 95-100% of ethyl-alcohol is injected into the tumor.
(For illustration): Radiofrequency Ablation (RFA) has a better cure rate than Percutaneous Alcoholablation (PEI). Why is Percutaneous Alcoholablation still used more in developing countries?
There are many people in developing countries with hepatitis A/B who develop tumors in the liver. It is known that RFA works better, but PEI is cheaper.
What is Irreversible Electroporation (IRE) (also called nano knife)?
With electrical pulses small (nano) holes are created in the cellular membranes of the tumor which destroys the cancer cells without any additional damage to surrounding tissues (which is the case for many therapies that include heat).
What is reversible electroporation?
Highly intense electric pulses create small pores in membranes. Because of this, DNA/medicine and other stuff can be transported from the extracellular compartment to the intracellular compartment.
When does reversible electroporation result in irreversible electroporation?
When the intensity of the electric pulses is increased (up to 3.000 V), the membranes is irreversibly damaged. This causes cells to go into apoptosis (not coagulation necrosis).
