Renal cell carcinoma (RCC) ranks third in the world in terms of morbidity among malignant neoplasms of the genitourinary system after tumors of the prostate and bladder. In terms of the growth rate of cancer incidence in North America, RCC steadily ranks second after prostate cancer. Every year, in the United States more than 65,000 men and women get kidney cancers, and about 14,000 men and women die from this diseases.
The widespread introduction of modern diagnostic methods has led to an increase in the detection rate of early-stage RCC. Currently, there is a decrease in the size of the primary detected kidney tumors with an increase in the proportion of T1 or low grade tumors and a decrease in the proportion of advanced RCC because of early detection and treatments. The number of patients with a tumor <4 cm in diameter has steadily increased. These trends undoubtedly led to an improvement in survival rates in these groups of RCC .
In connection with the migration of the stage of the tumor process towards localized RCC with a small tumor, new organ-sparing methods of treating RCC have been developed in the last two decades, such as laparoscopic kidney resection and most impressively ablative minimally invasive techniques such as cryoablation and microwave ablation both of which are done at LA Vascular.
The essence of a relatively new minimally invasive direction in oncourology consists in the local destruction of the tumor process, when energy is supplied to the lesion, leading to damage (ablation) of the affected area. These technologies are collectively called ablative techniques. Modern ablative approaches include both hyperthermal (radiofrequency ablation – RFA or newer microwave techniques) and hypothermal (cryoablation) methods which have the largest amount of supportive clinical data.
Ablative techniques destroy tumor tissue in situ (within the body) without requiring removal (surgical resection of the mass). Their main potential advantages include low complication rates, no hospital stay, earlier return to normal life, as well as preservation of parenchyma and renal function, lower cost of treatment and the possibility of treating patients with severe comorbidities who may not be candidates for surgery.
Cryoablation which is the method with the highest amount of research backing it causes destruction of the tumor by applying temperatures above below -20° C through needle. Alternatively RFA technique which is an older methodology is based on the conversion of radio frequency energy into tissue heating and subsequent coagulation necrosis. High-frequency radiation emanating from the needle electrode causes the excitation of ions and heating of tissues due to molecular friction, which leads to denaturation of proteins and destruction of cell membranes. These changes occur in 4-6 minutes. at temperatures> 50 ° C or immediately at temperatures> 60 ° C. Temperatures> 105 ° C cause tissue boiling and carbonization with the formation of gas bubbles and a decrease in the effectiveness of RFA for the formation of a larger focus of coagulation necrosis. The main purpose of RFA is to bring a temperature of 50–100 ° C to the entire volume of tumor tissue. The size of the coagulation necrosis zone depends on the impedance of the tissue, the time of RFA, the amount of supplied energy, and the surface area of the RFA electrodes. Exophytic tumors surrounded by avascular perirenal adipose tissue are more desirable for ablative techniques especially compared to central tumors surrounded by well-perfused, vascularized parenchyma, which acts as a heat and cold dissipating radiator.
Ablation can be performed using open, laparoscopic and percutaneous approaches. Percutanous approach is the method of choice in most cases as it is truly minimally invasive with shorter recovery times . Ablation using laparoscopic access has a number of other advantages, such as tumor mobilization, prevention of damage to adjacent organs and structures if they cannot be moved by other methods, and placement of RFA electrodes under visual control. Most of these advantages of ablation performed by laparoscopic methods can be abated with percutaneous ablation is performed by experienced hands as nearby structures can be moved with hydrodissection of air dissection where air and fluid are introduced between the mass and the critical structure so as to avoid injury to the other structures. Additionally as visualization with ultrasound and CT has improved percutaneous methods have become more popular.
Currently, ablation with percutaneous access, which can be performed on an outpatient basis, is more common. Ablation electrodes can be placed under ultrasound, CT and MRI guidance. The effectiveness of ablation can be assessed no earlier than after 1 month. after the manipulation, while according to the results of CT examination, the ablated tumor tissue should not take up a contrast agent.
The main indication for performing ablation of a kidney tumor is a well-visualized tumor under imaging and a mass measuring less than 4 cm in diameter, localized along the periphery of the kidney. Ablation can be performed in most patients with small kidney tumors. In particular, the use of ablation of kidney tumors is recommended for use in elderly patients with concomitant pathology (arterial hypertension, diabetes mellitus, kidney stones, renal failure, cardiovascular diseases, including a history of myocardial infarction). It is also permissible to use cryoablation in patients with a single kidney and in the presence of hereditary diseases (von Hippel-Lindau disease, tuberous sclerosis, hereditary papillary RCC)
When is kidney tumor ablation contraindicated?
– There are two contraindications for ablation of the kidney: firstly, it is an extremely serious condition of the patient, for example, sepsis, and secondly, it is severe disorders of the blood coagulation system (coagulopathy).