Thermoablation is a “mini-invasive” method that allows the destruction of tumor nodules thanks to the delivery of thermal energy carried directly from outside to inside the target, without removing it from the patient’s body (as is the case in surgery). The thermal energy can be produced from high temperatures or from very low temperatures, as in the case of cryoablation, which is currently used very little. In Humanitas thermoablation is used for the treatment of certain types of cancer, mainly hepatic, by radiofrequency or, especially in the last two years, by microwaves.
We talk about it with Professor Luigi Solbiati, professor of Radiology and consultant of Interventional Radiology in Humanitas.
“Energy for thermo-ablation can be produced by different types of equipment: historically, since the 90s, the first used was radio frequency, later on laser and microwave equipment were introduced. Whatever the type of equipment used, the tumor lesion is reached by crossing the skin (without surgical incisions) with an energy emitter similar to a needle (called “electrode”, “antenna” or “fiber” depending on whether it is respectively radiofrequency, microwave or laser), guided into the target thanks to imaging methods (ultrasound or, more rarely, CT).
The microwaves were introduced into clinical practice around 2009 and have now become routine treatment at Humanitas,” explains Prof. Solbiati.
When are microwaves used?
“Microwave thermoablation is absolutely effective (i.e. it definitely destroys the tumor in almost all cases) in tumors with sizes ranging from 3 to 3.5 centimeters. It is also possible to intervene on larger tumors (4-5 centimeters) when other types of therapy cannot be used, but it decreases the probability of having complete local control of the tumor and therefore increases the risk of relapse.
The heat not only destroys the tumor, but also a small part of the healthy surrounding tissue: this helps to limit the risk of local recurrence.
It should also be noted that in addition to a limit in terms of size, there is also a numerical limit. Treating many tumor targets (more than 4-5cm) in the same patient is technically difficult as well as often lacking in oncological value,” says the specialist.
What are the advantages of microwaves?
“The treatment with microwaves is fast, precise and relatively safe, that is, it is burdened by a very low rate of complications, certainly lower than that of the corresponding surgical procedures, also thanks to imaging techniques that become increasingly precise and reliable. When the tumor target is located in organs that can be studied with ultrasound, this method is the most suitable and used to guide thermoablation, thanks to its favorable characteristics (real-time vision, speed, ease of use, absence of ionizing radiation). However, if the target is not visible with ultrasound (or is only partially visible) because of its anatomical location or proximity to structures that “hide” it, it can be localized only by another more complex method of images and not “in real time” (CT, magnetic resonance or PET). In Humanitas we can resort to the so-called fusion of images in real time. This is an innovative method that allows you to blend, within the ultrasound, through the creation of a small electromagnetic field around the patient and the application of a sensor to the ultrasound probe, the real-time ultrasound with the method of image that best allows you to view the target (CT, MRI or PET). After a short “recording” phase, moving the ultrasound probe also moves the reference method to the same point of the patient and this allows the target (or the location in which it is located) to be visualized with the ultrasound and to guide the thermoablation by means of real-time ultrasound even in these “complex” cases.
In the vast majority of cases, in Humanitas we carry out the treatment without recourse to general anesthesia, but with the patient under sedation, further shortening the time required for the procedure. In this way, we are able to perfectly treat, for example, 3 cm nodules with a single insertion of the microwave antenna in 6-7 minutes, with a total time of patient stay in the interventional room of 45-50 minutes.
Another important advantage is the possibility of repeating the treatment over time. In patients with cirrhosis hepatocarcinoma, for example, different nodules may appear after months or years. We can intervene with microwave thermoablation on each of these, year after year, preserving the already scarce liver function of these patients as much as possible,” explains the professor.
Microwave and radio frequency comparisons
“With the same mini-invasiveness, the microwaves, with which much higher temperatures are reached inside the target (120-140°C compared to 90-95°C for radiofrequency) allow to perform wider treatments in shorter times, effective also in lesions adjacent to large blood vessels, where, instead, with radiofrequency results are much less effective due to the dispersion of heat caused by the blood flow, with a high risk of recurrence”.
Fields of application
“In Humanitas we use microwaves mainly in the liver, to treat hepatocarcinomas and liver metastases mainly from colorectal neoplasms and in pale cell renal tumors no larger than 3 cm.
Other important fields of application in great development are primary and metastatic lung tumors and osteolytic bone metastases, in which the combination of thermoablation (mainly for analgesic purposes) and radiotherapy allows to obtain very valid results.
Another recent field of application of thermoablation is that of neck pathologies, in particular metastatic adenopathies from papillary thyroid neoplasia relapsing after thyroidectomy and lymphadenectomy and thyroid strum, a disease very common in the population, provided it is no larger than 4-5 cm and in normal functioning thyroids, as an alternative to thyroidectomy. In the case of metastatic adenopathies (usually small and in very “delicate” areas) the laser must be used that allows treatments to be performed with millimeter precision, but not very extensive, while for the strum can be used both the laser and radio frequency, obtaining reductions in thyroid volume of up to 70-80%. In both pathologies the treatment is carried out in a day hospital regime, therefore without any hospitalization and with complications that are almost non-existent”, concludes Professor Solbiati.
