KIDNEY CRYOABLATION
INDICATION OVERVIEW

Cryoablation, occasionally called cryotherapy or cryosurgery, is a minimally invasive treatment (no incisions) that uses extremely cold temperatures to kill cancer tumors. It is a well-established technology for the treatment of many benign and malignant tumors and lesions, including kidney tumors. Very precise targeting and control of the extremely cold energy allow for efficient destruction of tumor cells while leaving healthy kidney tissue intact and functional.

KIDNEY ANATOMY

The kidneys are a pair of bean-shaped, fist-sized organs, located on either side of the spine just above waist level. As the chief organs of the urinary system, the kidneys are sophisticated reprocessing machines. Every day, the kidneys process about 200 quarts of blood to sift out about 2 quarts of waste products and extra water. The waste and extra water become urine.

Each kidney is composed of about one million microscopic “filtering packets” called nephrons. A complicated chemical exchange takes place in the nephrons as waste materials and water leave the blood and enter the urinary system. Each nephron connects to progressively larger tubular branches, until it reaches a large collection area called the calyx. The calices form a funnel-shape at the upper ureter called the renal pelvis. Urine moves from the renal pelvis through the ureters, the tubes that connect the kidney to the bladder. Urine leaves the body through another tube called the urethras.

KIDNEY CANCER

Kidney cancer, or renal cancer, is cancer that originates in the kidney. This cancer occurs most often in adults between the ages of 50 and 70, affecting men twice as often as women and is a rare cancer in children and young adults. There are two main types of kidney cancer, renal cell carcinoma (cancer that forms in the lining of the small kidney tubes that filter blood and remove waste) and renal pelvis carcinoma (cancer that forms in the center of the kidney where urine collects). Approximately 90% of adult kidney cancer is renal cell carcinoma (RCC).

Serious health problems occur when kidneys perform below 25% of full renal function. If function drops below 10-15%, some form of kidney replacement therapy is necessary to sustain life, such as dialysis or transplant. Therefore, preservation of maximum renal function is an important consideration in deciding the best treatment, especially if a patient’s kidney function is already below optimal.

a. Symptoms

The majority of kidney tumors are found during routine physical exams or during screening for other conditions. When initially discovered, many of these tumors are relatively small and the patient may not have experienced any symptoms.

The most common symptom of kidney cancer is blood in the urine, called hematuria. This may make the urine rusty or dark red in color. Sometimes the blood is not visible, but is only seen when a urine specimen is examined under a microscope. It may be discovered as part of a routine urinalysis performed during a regular physical exam.

Other symptoms of kidney cancer may include pain in the back or side that does not go away, a lump or mass on the side or the abdomen, unexplained weight loss, fever, feeling very tired, swelling in the legs or ankles, or having a general feeling of poor health. Most often, these symptoms do not indicate cancer. An infection, a cyst, or some other problem in the urinary system can cause these same symptoms.

b. Tests and Staging

Tests
If kidney cancer is suspected, laboratory and imaging tests may be conducted to confirm the diagnosis. Laboratory tests may include urinalysis (to look for blood or other substances in the urine), complete blood count (to measure the different cells in the blood), and blood chemistry tests (to evaluate chemicals in the blood and to assess kidney function).

Imaging tests are used to create pictures of the inside of a patient’s body. Energy (x-rays, sound waves, magnetic fields or radioactive particles) is sent through the body; as various body tissues change the energy pattern, a picture is created. These pictures can show normal and abnormal body structures. Computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound are the imaging modalities most commonly used to diagnose kidney tumors. A CT scanner uses x-rays to take multiple pictures as it rotates around the patient. A computer combines the pictures into cross-sectional images of the body that are evaluated by a radiologist. Similarly, MRI scans also provide detailed pictures of the body, but the energy source for MRI scans is a combination of radio waves and strong magnets. Ultrasound devices send sound waves into the body, pick up the echoes that bounce back from kidney tissue and convert the echoes into picture. The pictures created by the selected imaging modality provide information about the size, shape and location of a tumor.

Biopsy
Needle biopsy (removing a sample of tissue for microscopic examination by a pathologist) of a renal mass may be conducted to distinguish between benign lesions and renal cancer. The biopsy may be performed at a time prior to ablation or immediately prior to the ablation.

Staging
After a positive kidney cancer diagnosis has been made, a treatment plan must be created. One of the first steps in developing the plan is “staging” the cancer. The stage assigned describes the disease in a way that is understood throughout the medical community.

Renal cell carcinoma is commonly described using the TNM stages:

  • T – Refers to the tumor size and location (T1, T2, T3 or T4)
  • N – Describes whether lymph nodes are affected (N0 or N1)
  • M – Defines whether the cancer has spread beyond the kidney (metastases) (M0 or M1)

The T, N and M stages may be grouped together and described in numerical stages, ranging from I – IV:

  • Stage I – the earliest stage of kidney cancer; the tumor is less than 7cm (about 2-3/4 inches) in diameter (T1),) has not spread outside the kidney (M0), and there is no lymph node metastasis (N0).
    • T1a Tumor ≤ 4 cm in greatest dimension, limited to the kidney
    • T1b Tumor > 4 cm but < 7 cm in greatest dimension, limited to the kidney
  • Stage II – a fairly early stage of disease; the tumor is larger than 7 cm (T2), but the cancerous cells are still confined to the kidney (M0), and there is no lymph node metastasis (N0).
    • T2a Tumor > 7 cm but ≤ 10 cm in greatest dimension, limited to the kidney
    • T2b Tumor > 10 cm, limited to the kidney
  • Stage III – a kidney cancer stage described by one of the following:
    • The tumor has not spread outside the kidney, but cancer cells have been found in one nearby lymph node; or
    • The tumor has invaded the adrenal gland, the fat, and/or the fibrous tissue surrounding the kidney but has not spread beyond the fibrous tissue and cancer cells may be found in one nearby lymph node; or
    • Cancer cells have spread from the kidney to a nearby large blood vessel and cancer cells may be found in one nearby lymph node.
  • Stage IV – a kidney cancer stage defined by one of the following::
    • The tumor extends beyond the fibrous tissue that surrounds the kidney; or
    • Cancer cells are found in more than one nearby lymph node; or
    • The cancer has spread to a remote area of the body, such as the lungs.

Recurrent cancer is cancer that has come back after treatment. It may be found in the kidney(s) or elsewhere in the body.

Further Information

For further information, see:
Medicine Net
National Cancer Institute
Macmillan Cancer Support