Who are we?

Sirtex is a global life-sciences company that develops and delivers effective oncology treatments using novel small particle technology

What are SIR-Spheres microspheres? What are SIR-Spheres microspheres?

SIR-Spheres microspheres are a medical device used in interventional oncology to deliver Selective Internal Radiation Therapy (SIRT) to the liver.

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Approved Indication

SIR-Spheres 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).


SIR-Spheres microspheres are contraindicated in patients who have:

  • had previous external beam radiation therapy to the liver;
  • ascites or are in clinical liver failure;
  • markedly abnormal synthetic and excretory liver function tests (LFTs);
  • greater than 20% lung shunting of the hepatic artery blood flow determined by Technetium-99m macroaggregated human albumin (99mTc-MAA)  scan;
  • pre-assessment angiogram that demonstrates abnormal vascular anatomy that would result in significant reflux of hepatic arterial blood to the stomach, pancreas or bowel;
  • disseminated extra-hepatic malignant disease;
  • been treated with capecitabine within the two previous months, or who will be treated with capecitabine at any time following treatment with SIR-Spheres microspheres.
  • portal vein thrombosis.


  • Inadvertent delivery of SIR-Spheres microspheres to the gastrointestinal tract or pancreas will cause acute abdominal pain, acute pancreatitis or peptic ulceration. 
  • High levels of implanted radiation and/or excessive shunting to the lung may lead to radiation pneumonitis.
  • Excessive radiation to the normal liver parenchyma may result in radiation hepatitis.
  • Inadvertent delivery of SIR-Spheres microspheres to the gallbladder may result in cholecystitis.


  • No studies have been done on the safety and effectiveness of this device in pregnant women, nursing mothers or children.
  • Due to the radioactivity of this device and the significant consequences of misplacing the microspheres in situ, this product must be implanted by doctors with adequate training in the handling and implantation technique for this device.
  • Sirtex recommends a SPECT scan of the upper abdomen be performed immediately after implantation of SIR-Spheres microspheres. The SPECT scan will detect the Bremsstrahlung radiation from the yttrium-90 to confirm placement of the microspheres in the liver.
  • This product is radioactive. The use of this device is regulated under Title 10 of the Code of Federal Regulations Part 35. These regulations must be followed when handling this device.