Because of the wide spread use of imaging tools such as CT, ultrasound and MRI, more and more renal cancers (RCC) are diagnosed. These tumors are predominantly detected in the elderly and at a very early stage. Since surgery is more risky in elderly patients and these tumors are generally small, percutaneous cryoablation is preferred more and more in patients with RCC. Many studies have shown that cryoablation is at least as good as surgery in cancer control, but has less side effects and the risk of renal failure is lower. If RCC is in a solitary kidney, present in both kidneys or there are multiple RCCs in one kidney, cryoablation may be the best possible solution.
The most common renal cancer is renal cell carcinoma (RCC), which accounts for about 80% of cases. The majority of the remaining are transitional cell carcinoma that originate from urinary canals. Other primary tumors and metastases may also be present in the kidney, but they are very rare.
The RCC generally does not cause symptoms until it reaches large sizes. The most typical symptom is blood in the urine in the absence of pain. When the tumor reaches large dimensions, it can also cause pain in the abdomen. RCC is divided into 4 stages according to the size and extent of the tumor. The tumor is confined in the kidney at the first and second stage, which are called early stages. At stage 3, the tumor is spread out of the kidney, lymph nodes or kidney veins. At stage 4, metastases to distant organs are seen (most frequently in the lungs).
Why is it common?
Renal cell carcinoma or RCC is a type of cancer that has been quite common in recent years. The frequency has increased by 10 times compared to 50 years ago. The reasons for this are aging of the population that increases the incidence of cancer and more frequent use of ultrasound, tomography and MRI that increases incidental detection. Frequent use of these imaging modalities also allowed early detection of RCC. At present, 75% of RCC cases are detected at Stage 1a, which is the earliest stage (Tumor limited to kidney and less than 7cm).
How is it diagnosed?
The RCC is generally detected during radiological examinations such as ultrasound, CT, MRI, or PET-CT performed because of unrelated reasons. However, when a suspicious mass is detected in the kidney, it may not always be the renal cancer; although rare, benign tumors and metastases may be seen in the kidney. Therefore, the nature of the mass must be investigated by biopsy. The ideal method for biopsy in the kidney is ultrasound or CT guided trucut needle biopsy.
How is it treated?
RCCs are generally not sensitive to chemotherapy and radiotherapy, so the most frequently performed treatment is surgery. The most common operation is the removal of the whole kidney (nephrectomy). However, at the early stages, it may be sufficient to take a part of the kidney (partial nephrectomy). Biological therapies and immunotherapy may be tried in patients who cannot be operated, but these methods are useful in only a small number of patients.
New treatment methods
Percutaneous cryoablation is one of the most commonly used treatment modalities in renal cancers. Cryoablation is ideal for the treatment of kidney tumors in many respects;
1. Today, a large proportion of RCCs are detected incidentally in examinations such as ultrasound, tomography, or MRI, before the tumor has not yet grown to give symptoms. The majority of these tumors are stage 1 tumors smaller than 7 cm in diameter, limited to kidney, and non-metastatic. The vast majority of these tumors are suitable for cryoablation.
2. Most of the RCCs detected incidentally occur in individuals over the age of 50-60 with comorbid conditions such as heart-lung disorders or kidney problems that can make surgery dangerous. In such individuals, cryoablation, which is performed only with local anesthesia and does not require long hospitalization, is a very attractive option.
3. Long-term (5-10 years) results of renal cryoablation have been published in recent years. According to these results, cryoablation is equally successful with partial nephrectomy, but has less side effects, provides better renal function and higher patient satisfaction. The most suitable tumors for cryoablation are those less than 5 cm in size and not metastasized, although tumors upto 8 cm have been successfully treated in some centers including ours.
4. In some patients, surgery may be more dangerous; for example if RCC develops in the solitary kidney, or in both kidneys, or if there are multiple RCCs in the same kidney, surgery may be very challenging and more risky. In such patients, cryoablation should be considered the first option.
Standard ablation method in renal cancers is cryoablation. In the past, cryoablation was performed surgically by urologists. Nowadays, it is done by interventional radiologists nonsurgically, by putting needles from the skin under ultrasound and CT guidance (percutaneous cryoablation) with local anesthesia and mild sedation. Depending on the size of the tumor, it may be necessary to use 3-4 needles (cryoprobes). Typically the tumor is frozen and thawed (melting) 2 times for 10 minutes, which lasts for about 30 minutes. The iceball formed during the procedure can be easily seen on CT. Therefore, the ablation area can be adjusted to provide the best coverage of the tumor by increasing the number or power of the probes.
Although 'heating' methods such as radiofrequency (RF) and microwave are also used in kidney cancers these methods have 3 major disadvantages compared to cryoablation:
1. The ablation site cannot be seen during the procedure, so it cannot be understood if the tumor is completely destroyed. In contrast, during cryoablation, the ablation area is clearly seen as a dark iceball on CT, MRI and ultrasound, and its size can be adjusted as required.
2. The ablation area of RF and microwave is (usually well below 3 cm). However, in cryoablation, the size of the ablation area can be enlarged by increasing the number and power of needles.
3. RF and microwave ablation is painful. Therefore, general anesthesia is used. This may be risky in elderly patients with RCC. In contrast, since cryoablation is not painful, local anesthesia is sufficient.
For these reasons, cryoablation is the preferred method in percutaneous ablation of RCC.
Why cryoablation instead of surgery
1. If performed at experienced centers, it is at least as successful as partial nephrectomy for cancer treatment.
2. Side effects is less and milder, it does not disrupt kidney function.
3. No anesthesia, no incision stitches, it is done through needle holes under local anesthesia.
4. The hospital stay is usually only 1 day, the patient can return to normal life immediately.
Which patients are eligible?
The ideal patients for cryoablation are RCC cases smaller than 5 cm and not metastasized. Apart from these, in some patient groups, partial nephrectomy is high risk and cryoablation should be preferred. These include patients with impaired renal function, those with heart and lung problems, those with a kidney already removed, those with RCC in both kidneys, and more than one RCC in the same kidney.
Video: Cryoablation: freezing kills kidney tumors
Interventional oncology in cancer management
Prof Saim Yilmaz, MD