What are SIR-Spheres® Y-90 resin microspheres?
SIR-Spheres Y-90 resin microspheres are microscopic resin beads that contain the radioactive isotope Yttrium-90 (Y-90) and emit radiation to kill cancer cells. Due to their small size (1/3 the width of a human hair) and similar density to blood cells, the microspheres travel easily with the bloodstream directly to the liver tumors. The microspheres become lodged inside the tumor and kill the cancer cells through radiation. Selective Internal Radiation Therapy (SIRT) with SIR-Spheres Y-90 resin microspheres is considered a well-tolerated and effective method of using radiation to treat colorectal cancer that has spread to the liver and is often used in conjunction with chemotherapy. SIR-Spheres Y-90 resin microspheres are manufactured by Sirtex Medical Limited which is headquartered in Australia and has U.S. operations in Woburn, Massachusetts.
What do SIR-Spheres Y-90 resin microspheres treat?
SIR-Spheres Y-90 resin microspheres are approved to treat colon and rectal cancer which has spread to the liver. In the United States, colorectal cancer is the second leading cause of death by cancer. The liver is the most common site for the spread of this cancer.
Can you describe the SIR-Spheres Y-90 resin microspheres procedure?
The SIR-Spheres Y-90 resin microspheres treatment is performed as an outpatient procedure by specially trained physicians called interventional radiologists. Using the liver's unique blood supply, millions of tiny resin microspheres loaded with Yttrium-90 (Y-90) are released into the liver blood circulation. The radioactive microspheres lodge in the blood supply of the tumor, where they emit radiation for about two weeks.
The treatment normally takes about 60 to 90 minutes, with most patients returning home four to six hours later. Patients are carefully monitored throughout and after the procedure. The most commonly reported side effects are flu-like symptoms over one to three weeks. The procedure can be performed in combination with chemotherapy or by itself.
How effective is the treatment?
Clinical studies have shown that SIRT with SIR-Spheres Y-90 resin microspheres increases the length of time that the cancer is stable and not growing without adversely affecting the patient's quality of life.1,2,3 In clinical studies, the SIRT procedure has been combined with chemotherapy, given as a single procedure during a chemotherapy holiday or after chemotherapy options have failed.
Who is eligible for treatment with SIR-Spheres Y-90 resin microspheres?
SIR-Spheres Y-90 resin microspheres are the only fully FDA PMA-approved Y-90 microspheres for colorectal cancer that has spread to the liver.4 The treatment offers hope for patients who have one or more colorectal liver tumors which cannot be treated by surgical resection or ablation.
Where is the procedure performed?
The procedure is performed at a hospital or clinic on an outpatient basis by highly trained physicians called interventional radiologists.
How are SIR-Spheres Y-90 resin microspheres delivered?
During the procedure, the interventional radiologist threads a tiny catheter through the large artery in the leg. Then the catheter is advanced into the hepatic artery, which supplies the liver tumors with blood. Once the catheter is in position, millions of microspheres are delivered directly to the tumor site. The SIR-Spheres Y-90 resin microspheres become lodged in the tumor bed and emit radiation to the tumors, while the surrounding healthy liver tissue remains unaffected.
How are SIR-Spheres Y-90 resin microspheres different from other treatments?
Radiation is an effective therapy which is often used to treat cancer. However, normal liver cells are very sensitive to radiation. The targeted nature of SIR-Spheres Y-90 resin microspheres therapy enables doctors to deliver up to 40 times more radiation to the liver tumors than would be possible using normal external beam radiotherapy, while sparing the surrounding healthy liver tissue from damage.
How common is this procedure?
SIR-Spheres Y-90 resin microspheres are currently being offered at more than 1000 sites around the world, including more than 300 centers in the U.S. Over 73,000 doses of SIR-Spheres Y-90 resin microspheres have been supplied worldwide.
Other than treating the cancer, what are the benefits to the patients?
Besides offering patients an effective treatment option to control the spread of the cancer in their liver, therapy with SIR-Spheres Y-90 resin microspheres also help patients maintain a good quality of life. The procedure is performed as an outpatient service which minimizes the time spent at the hospital and results in relatively minimal side effects.
What are the likely side effects?
Almost all treatments and drugs produce unwanted side effects. Most side effects following a SIRT procedure are minor, but a small number can be serious. Many patients experience abdominal pain or tightness in their abdomen, nausea and loss of appetite which normally subsides within a week. Patients may also develop a mild fever that may last for up to a week and fatigue which may last for several weeks.
What are the potential complications?
In rare instances, a small number of microspheres may inadvertently reach other organs in the body, such as the gallbladder, stomach, intestine, or pancreas. If microspheres reach these organs, they can cause inflammation or ulceration. These complications are rare, but if they do occur they will require additional medical treatment.
Do patients have to take special precautions?
There are some simple precautions that patients need to take during the first 24 hours following the SIRT procedure. These precautions include: thorough hand washing after using the toilet, and cleaning up any spills of body fluids such as blood, urine or stools and disposing of them in the toilet. Otherwise, patients can resume normal contact with family members.
Patients must not receive SIRT treatment if they are pregnant, and must not become pregnant within two months of receiving the treatment as this may cause harm to the unborn baby.
Does insurance cover the procedure?
Most insurance companies generally cover the cost of SIR-Spheres Y-90 resin microspheres for the treatment of colorectal cancer which has spread to the liver. Under the terms of the Medicare Prescription Drug Improvement and Modernization Act (MMA) of 2003, Medicare, for the most part, reimburses hospitals for the cost of outpatient treatment with SIR-Spheres Y-90 resin microspheres. Many private payers have recognized the safety and efficacy of the SIR-Spheres Y-90 resin microspheres procedure and have issued positive coverage policies for treatment.
1. Hendlisz A et al. J Clin Oncol. 2010;28:3687-3694.
2. Gray B et al. Ann Oncol. 2001;12:1711-1720.
3. Seidensticker R et al, Cardiovascular Interventional Radiology, 2011 July 29; Epub.
4. SIR-Spheres Y-90 resin microspheres are indicated for the treatment of unresectable metastatic liver tumors from primary colorectal cancer with adjuvant intra-hepatic artery chemotherapy (IHAC) of FUDR (Floxuridine).