Cancer Care

  Lee Riley, MD, PhD
  Darius Desai, MD
  Susan Chang, MD

801 Ostrum Street
Bethlehem, PA

(610) 954-2140

(610) 954-6055

St. Luke's Hospital & Health Network


Selective Internal Radiation Therapy (SIRT) at St. Luke's Hospital

The SIR-Spheres® are delivered through a catheter placed in the femoral artery of the upper thigh and threaded through the hepatic artery (the major blood vessel of the liver) to the tumor site. The spheres are trapped in the tumor’s small blood vessels, where they destroy the tumor from inside.

Selective Internal Radiation Therapy (SIRT) is a new treatment for cancers that have spread to the liver and cannot be removed surgically.  The technique uses new approaches to deliver radiation directly to the tumors.

Conventional external beam radiotherapy has to go through the healthy liver in order to reach most liver tumors.  This severely limits the total radioactive dose that can be given to a tumor.   SIRT, on the other hand, involves the delivery of millions of microscopic radioactive spheres through the blood stream directly into the liver tumors. The targeted nature of SIRT enables physicians to deliver up to 40 times more radiation to the liver tumors than would be possible using conventional radiotherapy.

SIRT Process

Using millions of microscopic radioactive spheres, called SIR-Spheres®, the SIRT process enables the specific targeting and destruction of tumors within the liver that would otherwise be inaccessible. Unlike current, conventional chemotherapy treatments, the highly specific nature of the SIRT process increases the effectiveness in killing the cancer while minimizing harmful side effects to surrounding healthy tissue.

SIR-Spheres® are delivered through a catheter placed in an artery and threaded into the liver artery to the site of the tumor. The microscopic spheres are bonded to a radioactive molecule, yttrium-90.  The microspheres are trapped in the tumor’s vascular bed, where they destroy the tumor from inside. The radiation is wholly contained within the patient’s body, and after 14 days, only 2.5 percent of the radioactive activity remains.

Unlike chemotherapy, which is administered multiple times, SIRT is typically administered to the patient in one or two treatments. The treatment is considered outpatient, and patients normally go home within 24 hours.

Patient Outcomes

Treatment with SIR-Spheres® is generally not regarded as a cure, but has been shown to shrink the cancer more than chemotherapy alone. On occasion, patients treated with SIR-Spheres® have had such marked shrinkage of the liver cancer that the cancer can be surgically removed at a later date. This has resulted in a long-term cure for some patients.

The FDA has approved SIR-Spheres® for the treatment of colorectal cancer that has spread to the liver.

Patients suitable for treatment with SIR-Spheres®generally:

bulletHave inoperable secondary (from colorectal primary) liver cancer
bulletHave the liver as the major site of the disease
bulletHave sufficient remaining healthy liver still functioning satisfactorily
bulletAre well enough to tolerate the implant
bulletMeet the pre-selection criteria, as determined by their doctors’ pre-treatment testing

SIR-Spheres® are contraindicated in patients who have:

bulletHad previous external beam radiation therapy to the liver
bulletAscites, or are in clinical liver failure
bulletMarkedly abnormal synthetic and excretory liver function tests
bulletTumors amenable to surgical resection for cure
bulletGreater than 20 percent lung shunting (determined by the nuclear medicine breakthrough scan)
bulletPre-assessment angiograms and MAA nuclear scans that demonstrate significant reflux of hepatic arterial blood to the stomach, pancreas or bowel
bulletWidely disseminated or extra-hepatic disease
bulletBeen treated with capecitabine within the previous two months, or who will be treated with capecitabine at any time following treatment with SIR-Spheres®


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