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SIR-Spheres

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General Information About SIR-Spheres® Microspheres

If you or a loved one has been diagnosed with colorectal cancer that has spread (metastasized) to the liver, it is important to learn the facts and evaluate your treatment options. Of the 150,000 Americans diagnosed with colorectal cancer each year, more than 60 percent develop liver tumors. A diagnosis of colorectal liver metastases can be overwhelming, but there is hope.

SIR-Spheres® microspheres, or Selective Internal Radiation Therapy, are offered at Regions Hospital, and are a targeted radiation therapy that delivers a dose of internal radiation up to 40 times higher than conventional external beam therapy while sparing healthy tissue. This maximizes the treatment’s effectiveness and reduces the risk of injury to the liver. The treatment is typically administered as an outpatient procedure at a local treating hospital. SIR-Spheres microspheres are the only fully FDA-approved microspheres for patients with inoperable metastatic colorectal cancer to the liver.*

Who is a candidate for the treatment?
This treatment is indicated for patients with colorectal liver cancer whose liver metastases cannot be surgically removed. As with any treatment, the medical team at St. Paul Radiology can help you decide if this treatment is best suited for your condition. Potential candidates for SIR-Spheres microspheres include:

  • Patients with unresectable liver-dominate metastatic disease.
  • Patients who have received chemotherapy regimens, or for whom chemotherapy regimens are planned.
  • ECOG performance scale <2.
  • Life expectancy of >3 months.
  • Bilirubin <2.0 mg/dL.

How are SIR-Spheres microspheres administered?
SIR-Spheres microspheres are administered through a process called Selective Internal Radiation Therapy (SIRT). During the procedure, an interventional radiologist makes a small puncture, usually into the femoral artery near the groin. A small flexible tube, known as a catheter is then guided through the artery into the liver and millions of microscopic spheres (about a third of the width of a human hair), are delivered directly into the tumor. The entire procedure takes about 90 minutes. Patients will be sleepy during the procedure but able to communicate with the doctor and the team. Most patients return home four to six hours following treatment.

How do SIR-Spheres microspheres work?
The SIRT procedure delivers radiation, which is often used to treat cancer, directly into the liver tumors by using the tumor’s own blood supply. Normal liver tissue takes about 90 percent of its blood supply from the veins, while liver tumors receive about 90 percent of their blood supply from arteries. This allows SIR-Spheres microspheres to target the liver tumors with a tumor-killing dose of radiation via the hepatic artery, while sparing surrounding healthy liver tissue. This typically isn’t possible with conventional external beam radiation.

How are SIR-Spheres microspheres different from other radiation treatments for cancers of the liver?
SIR-Spheres microspheres usually either reduce or eliminate liver tumors after just one treatment. The targeted nature of SIR-Spheres microspheres therapy enables doctors to deliver more radiation to the liver tumors than would be possible using conventional radiotherapy. Also, because traditional radiation is delivered to a general area of the body where cancer exists, it is less exact than SIR-Spheres microspheres. Another limitation of conventional radiotherapy is that it can only be applied to certain areas of the body, often not including the liver. SIR-Spheres microspheres, however, are designed specifically for delivery directly to the liver.

What are the goals of treatment using SIR-Spheres microspheres?
Clinical trials have shown SIRT increases the time-to-disease progression and overall survival without adversely affecting the patient’s quality of life. In clinical studies, SIR-Spheres microspheres have been combined with modern chemotherapy or administered as a monotherapy during a chemotherapy holiday and have been proven to:

  • Decrease the tumor burden in the liver.
  • Increase time-to-disease progression.
  • Increase survival time.
  • Potentially downsize tumors to liver resection or ablation.
  • Provide palliation of symptoms.

What side effects and complications can I expect?
When properly administered, most side effects are typically mild and subside within several days. Post treatment side effects can include abdominal pain and/or nausea which normally subside after a short time and/or with routine medication. Patients may also develop a mild fever that may last up to a week and fatigue which may last for several weeks. As a precaution, we may recommend additional medications with the aim of preventing or minimizing these side effects.

In rare instances there is a possibility that a small number of microspheres may inadvertently reach other organs in the body, such as the gall bladder, stomach, intestine or pancreas. If SIR-Spheres microspheres reach these organs, they may cause inflammation of the gall bladder (cholecystitis), stomach (gastritis) or intestine (duodenitis). These complications are rare, but if one of these occurs, they will require additional treatment. Your treatment team will have received special training to minimize these risks and to prevent them from happening.

*SIR-Spheres microspheres are indicated for the treatment of unresectable metastatic liver tumors from primary colorectal cancer with adjuvant intra-hepatic artery chemotherapy (IHAC) using FUDR (Floxuridine)

SIR-Spheres® is a registered trademark of Sirtex SIR-Spheres Pty Ltd

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Selective Internal Radiation Therapy Physicians at St. Paul Radiology


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About SIR-Spheres® Microspheres

St. Paul Radiology now offers SIR-Spheres® Microspheres - Selective Internal Radiation Therapy (SIRT)