Nonsurgical Treatments for Metastatic Cancer in Bones

Interventional Radiologists Help Reduce Pain and Improve Quality of Life

Bones are the third most common location where cancer cells spread and metastasize. Each year, about 100,000 cases of bone metastasis are reported in the United States. Bone metastases occur when cancer cells gain access to the blood stream, reach the bone marrow, begin to multiply and then grow new blood vessels to obtain oxygen and food--which in turn causes the cancer cells to grow more and spread.

Some bone metastases become painful because the tumor eats away at the bone, creating holes that make the bone thin and weak. As the bones are replaced with tumor, nerve endings in and around the bone send pain signals to the brain. If left untreated, bone metastases can eventually cause the bone to fracture, seriously affecting a patient's quality of life. This is particularly true for long bones of the extremities where a fracture may render a limb nonfunctional. These patients may require surgical intervention to restore the function of their limbs. More commonly, metastases involve the ribs, pelvis, and spine.

For the most part, the goal of treating bone tumors is not curative, but rather palliative by reducing pain, preventing additional bone destruction, and improving function.

In treating cancer patients with painful bone metastases, interventional radiologists may use one of the two different thermal ablation techniques--radiofrequency ablation and cryoablation. This form of therapy is aimed at desensitizing the bone by killing the nerve endings in the vicinity of the metastasis. They can also treat painful vertebral metastases or fractures with vertebroplasty.

Prevalence

  • Bone is the third most common site of metastatic cancer.
  • About 100,000 cases of bone metastasis are reported each year in the United States. Of those reported, 75 percent are caused by tumors in the breast, prostate, lung and kidney.

Symptoms

  • Bone pain affects 70 percent of patients with bone metastases
  • Bone fracture
  • Spinal cord compression

Bone Cancer Diagnosis

There are a number of tests that can help in the diagnosis of cancer, including blood tests, physical examination and a variety of imaging techniques including X-rays (e.g., chest X-rays and mammograms), computed tomography (CT), magnetic resonance (MR) and ultrasound. Usually, however, the final diagnosis cannot be made until a biopsy is performed. In a biopsy, a sample of tissue from the tumor or other abnormality is obtained and examined by a pathologist. By examining the biopsy sample, pathologists and other experts also can determine what kind of cancer is present and whether it is likely to be fast or slow growing. This information is important in deciding the best type of treatment. Open surgery is sometimes performed to obtain a tissue sample for biopsy. But in most cases, tissue samples can be obtained without open surgery with interventional radiology techniques.

Needle biopsy

Needle biopsy, also called image-guided biopsy, is usually performed using a moving X-ray technique (fluoroscopy), computed tomography (CT), ultrasound or magnetic resonance (MR) to guide the procedure. In many cases, needle biopsies are performed with the aid of equipment that creates a computer-generated image and allows radiologists to see an area inside the body from various angles. This "stereotactic" equipment helps them pinpoint the exact location of the abnormal tissue.

Needle biopsy is typically an outpatient procedure with very infrequent complications; less than 1 percent of patients develop bleeding or infection. In about 90 percent of patients, needle biopsy provides enough tissue for the pathologist to determine the cause of the abnormality.

Advantages of needle biopsy include:

  • With image guidance, the abnormality can be biopsied while important nearby structures such as blood vessels and vital organs can be seen and avoided.
  • The patient is spared the pain, scarring and complications associated with open surgery.
  • Recovery times are usually shorter and patients can more quickly resume normal activities.

Large core needle biopsy. In this technique, a special needle is used that enables the radiologist to obtain a larger biopsy sample. This technique is often used to obtain tissue samples from lumps or other abnormalities in the breast that are detected by physical examination or on mammograms or other imaging scans. Because approximately 80 percent of all breast abnormalities turn out not to be cancer, this technique is often preferred by women and their physicians because it:

  • is less painful and requires less recovery time than open surgical biopsy, and
  • avoids the scarring and disfigurement that may result from open surgery.

A similar technique called fine needle aspiration can be used to withdraw cells from a suspected cancer. It also can diagnose fluids that have collected in the body. Sometimes, these fluid collections also may be drained through a catheter, such as when pockets of infection are diagnosed.

Many interventional radiology procedures for the diagnosis and treatment of cancer can be performed on an outpatient basis or during a short hospital stay. In many cases, the procedures:

  • offer new minimally invasive cancer treatment options.
  • are less painful and debilitating for patients.
  • result in quicker recoveries.
  • have fewer side effects and complications.

Bone Cancer Treatments

As vascular experts, interventional radiologists are uniquely skilled in using the vascular system to deliver targeted treatments via catheter throughout the body. In treating cancer patients, interventional radiologists can attack the cancer tumor from inside the body without medicating or affecting other parts of the body.

Thermal Ablation Treatments

Radiofrequency Ablation

Radiofrequency ablation (RFA) offers a nonsurgical, localized treatment that kills the target tissue with heat, while sparing the healthy tissue. Because of the localized nature of this treatment, RFA does not have any systemic side effects. Radiofrequency ablation can be performed without affecting the patient's overall health and most people can resume their usual activities in a few days.

In this procedure, the interventional radiologist uses imaging to guide a small needle through the skin into the tumor. From the tip of the needle, radiofrequency energy is transmitted into the target tissue where it produces heat and kills the tumor. Although the dead tumor tissue shrinks, the bone that is already eaten away will not grow back.

Click on images to enlarge

Efficacy

Preliminary studies have demonstrated that RFA significantly reduced bone pain from metastatic disease in over 90 percent of patients who had failed or were not suitable candidates for conventional therapy. In these studies, there were only few patients who suffered any side effects or complications. Therefore, RFA was demonstrated to be safe and effective in selected patients. A multicenter clinical trial is underway to further investigate the role of RFA in management of painful bone metastases. A direct comparison of RFA and radiation therapy may be warranted in the future.

Benefits

  • May be performed under conscious sedation or general anesthesia
  • Is well tolerated. Most patients can resume their normal routines the next day and may feel tired only for a few days.
  • Can be repeated if necessary
  • May be combined with other treatment options
  • Can relieve pain and suffering for many cancer patients

Cryoablation

Cryoablation is similar to RFA in that the energy is delivered directly into the tumor by a probe that is inserted through the skin. But rather than killing the tumor with heat, cryoablation uses an extremely cold gas to freeze it. This technique has been used for many years by surgeons in the operating room, but in the last few years, the needles have become small enough to be used by interventional radiologists through a small nick in the skin, without the need for an operation. The "ice ball" that is created around the needle grows in size and destroys the frozen tumor cells.

Vertebroplasty

The spine is one of the most common sites of metastasis. Vertebral bodies involved by the tumor may become painful and may eventually fracture. Surgical intervention with reconstruction of the spinal column is indicated only if the tumor causes compression of the spinal cord or instability of the spine. Vertebroplasty is an outpatient procedure performed using conscious sedation. An interventional radiologist inserts a needle through a small incision in the back, directing it under fluoroscopy (continuous, moving X-ray imaging) into the fractured vertebra. The physician then injects a medical-grade bone cement into the vertebra. The cement hardens within about 15 minutes and stabilizes the fracture. This treatment reduces pain, prevents further collapse of the vertebra, and restores mobility. Vertebroplasty dramatically improves back pain within hours of the procedure, provides long-term pain relief and has a low complication rate, as demonstrated in multiple studies.

Bone Cement Injection Diagram
Bone cement is injected to stabilize collapsed bones in the spine and relieve pain.

 

Reprinted with permission of the Society of Interventional Radiology © 2010
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