Interventional radiology: an interview with Dr. Luís Rosa
We interviewed Dr. Luís Rosa, regarding his vast experience on inverventional oncology, so that we can understand what are the benefits of these procedures in specific situations.
What is your position at the Champalimaud Centre, and what exactly do you do?
I am part of the Radiology Department, a specialist in diagnostic imaging with a further differentiation in interventional radiology.
This field is dedicated to minimally invasive procedures guided by the techniques with which we, radiologists, are already familiar in the diagnostic setting, namely ultrasound, CT and angiography.
There is a side branch of interventional radiology dedicated to diagnostic and therapeutic procedures in oncology, which is called interventional oncology.
This is a broad field of intervention including many and disparate types of procedures, including getting tissue samplings, ablating lesions, delivering drugs regionally to tumours through the arteries, to name just a few. What these procedures have in common is that they are guided by imaging techniques, allowing for more precision, efficacy and less morbidity, in cancer patients.
It is this field of Interventional Oncology, which is particularly exciting, that I am developing at the Champalimaud Centre.
Many people are familiar with radiology as a diagnostic procedure but could you explain a little more about how these techniques can be used as treatment?
There are many ways, but let’s use a biopsy as an example: this is not a treatment exactly, but it is a procedure we can talk about to illustrate a wider point. Imagine that there is a nodule, say in the liver, deep in the liver, unobservable from the outside of course, and you have basically to find what kind of nodule it is – whether it is benign or malignant. You have two possibilities of access: you can surgically open the patient, open the liver, take out a sample of the nodule and see what it is. This possibility is seldom used, because nowadays we have another option: we can use ultrasound or CT to see where the nodule is, coordinate the exact location of the nodule, introduce a needle, guide the needle with real time ultrasound and remove a sample.
Now, let’s assume that the biopsy has been completed and it reveals that the nodule needs to be removed or destroyed. You again have the option to surgically open the patient and take the nodule out. But if the nodule is small enough (3-5cm) you can ablate the nodule with a radiofrequency needle, a procedure which is called percutaneous ablation. This needle is inserted into the centre of the nodule where its tip will deliver thermic energy, thus creating a sphere of ablation – an area of uniformly distributed, controlled heat – which can destroy the nodule from the inside. This is one example of a treatment for lesions that doesn’t involve opening the patients.
Another way to treat lesions is through arterial or venous access – what we call a catheterism. You take a Seldinger needle into a peripheral vein or, more commonly, an artery of the patient and throw this access you pass a catheter on a special kind of wire and navigating through the vascular system you eventually reach the vessel(s) of the organ that you need to treat. Then you deliver the chemotherapy agent or whatever it is that you need to be delivered. This is a localised treatment, so you are avoiding releasing the chemotherapy into healthy tissue and organs as much as possible. You are administering the substance regionally to the specific organ where the lesions are.
There are variations of this technique, for example using pharmacological beads embedded with the chemotherapy agent. Thousands of these tiny beads are injected into the organ via catheter and the beads are drawn to the tumour, where they release the chemotherapy agent over a period of hours or days. This way, you avoid or at least minimize the systemic effect of chemotherapy.
A final example is to embolise the tumour (stop blood flow to the tumour) with beads, without using drugs. So, you just impact the beads into the vascular bed, where they stop vascular flow to the tumour. The tumour will, hopefully, shrink, become necrotic and destroyed.
There are many considerations and many options for different kinds of treatments, I have just given a few examples but there are many, many more. The core idea is that interventional radiologists do minimally invasive procedures using imaging techniques and this is called, as I said, Interventional Oncology.
So what are the advantages of interventional radiology in the above example?
The advantages of minimally invasive procedures are many: less complications, less time in recovery, less scarring, less pain, less blood-loss.
However, and let’s be very clear on this, if there is a surgical curative option, that should be offered to the patient. Complete resection of the tumour, if possible, is the preferable choice. With most lesions in lung cancer, liver cancer, metastasis etc., if the surgeon can enter with a curative intention, this is the usually the best course of action. Even if this requires a higher level of invasiveness, that is often the best option for the patient.
But, a large percentage of cancer patients simply do not have this option because of the extension of the disease, its localization or associated comorbidities.
In many cases Chemotherapy, Interventional Oncology, Radiotherapy, amongst other treatments, can be used to “downstage” patients: to reduce the burden of the disease, perhaps creating conditions for the surgeons to find a curative intervention.
In situations where no curative intention can be found, we turn our focus onto palliative care. This means increasing the life expectancy and the quality of life for our patients through minimally invasive procedures. I think that it is in this context that Interventional Oncology has a major role.
As an example, patients with liver metastases from, say, colon cancer have a low life expectancy if there is no surgical approach possible. But we can reduce the burden of the disease and interfere with the natural progression of the disease, increasing life expectancy and quality of life for these patients, possibly to the point where the disease becomes manageable and a relatively normal lifestyle can be achieved.
We know that you are a leading exponent of treatment with Yttrium 90 (Y-90). Could you please explain what this is and what it is used for?
Ok, I will start with an example: Let’s return to the regional hepatic intravascular treatments that we just talked about. You put the tip of a catheter in the lumen of the hepatic artery. If you inject something in the hepatic artery, through the catheter, it will spread throughout the liver. Now, tumoral nodules, in general, are more hypervascular – have more blood vessels, more density of capillaries and small arteries – than the liver itself. They are, what we call, “arterialised”. With radioembolization as with other vascular techniques you are trying to put to good use this characteristic of tumours.
So, Y-90 is a chemical radioactive element, producing Beta-radiation which has a penetration of 2.5mm around itself.
You load this element into a carrier – small glass or resin spheres – which are injected into the tumour.
The treatment consists in the injection of thousands, even millions, of these around 40 micron-sized spheres loaded, or marked, with Y-90 it he liver arterial circulation with the goal of reaching preferentially, given the above mentioned “artherialization”, the liver tumours sparing as much as possible the parenchyma, i.e. the healthy part of the organ .
In the past, radiotherapy was not very useful in the liver because the dose needed to destroy the tumour was also destroying the liver itself. With Y-90, as well with new more localized modalities of external radiotherapy, (SBRT) we can increase the dose of radiation to destroy the tumour, without increasing the damage to the liver.
The great advantage of radioembolization with Y- 90 is that you can treat more diffuse disease than with SBRT.
Is this form of treatment safe?
This sort of treatment has to be carefully planned and administered, using a multidisciplinary approach. The role of Nuclear Medicine is particularly important since all the planning of dose and evaluation of the distribution of radiation is on the hands of specialists in this field. Fortunately we have an enthusiastic and dedicated team of Nuclear Medicine physicians at our institution that assure a high level of radiation safety.
The decision to perform the treatment is also made by a Multidisciplinary Team, including Oncologists and Hepatobiliary surgeons, because alternative treatment strategies have to be taken into account.
The indications for this treatment should be established only in patients for whom there is no surgical option, no possible radiofrequency or ablative techniques or radiotherapy options. Patients that are submitted to Y-90 – or radioembolisation, it’s the same thing – typically have a diffused involvement of the liver. They need to still have good hepatic function and a small amount of disease – i.e. if a patient has metastasis in the liver and also in the lung, for example, this option may not be beneficial.
As you can see, a lot of care is taken to ensure that only patients that are in suitable circumstances receive the treatment.
The radiation itself only affects an area 2.5mm around the spheres. In fact, the patients are sent home the day after treatment because there is no risk of irradiating other people, or that other organs will be affected. 12.5 days after the treatment, the radiation is residual – that is, less than 5% of what was administered.
The point is, you have to be extremely careful in the preparation and administration of the procedure because you have to embolise to stop the flow of blood to any other organ that comes from the liver’s arteries. But assuming that the preparation is done properly, as of course it always should be in any procedure, the treatment is quite safe.
In fact, almost all patients who have experienced chemotherapy and Y-90 say that their quality of life is much better after the Y-90 treatment.
Can you tell us about the international “Liver Beyond Surgery in Colorectal Metastasis” meeting you are organising for November?
Surgical or chemotherapy meetings and conferences often mention Interventional Oncology, but generally it is a side issue, satellite of the main topics. We intend to invert that, not because we doubt the value of surgery or chemotherapy, but because we want to raise awareness of these minimally invasive treatments and of their beneficial effect in selected patients.
The intention of the meeting is to highlight the importance of the procedures of interventional oncologists in specific situations of patients with hepatic metastases from colorectal cancer. Unfortunately, this particular pathology is very common and our goal is to call attention to the option of interventional radiology in these cases. We can downstage patients for surgery. We can treat patients who are not responding well to chemotherapy. We can ablate tumours easily and efficiently. We hope to illustrate to oncologists and hepatic surgeons the potential of this kind of therapy: in the right setting, with the right indications, in selected patients, we can make a difference.