Nuclear Oncology using Microspheres

A small solution delivering big benefits

Radionuclide therapy involves the use of a radiopharmaceutical – a drug with a radioactive isotope that has the ability to destroy abnormally functioning or cancerous cells.

Selective internal radiation therapy (SIRT) is an innovative, targeted therapy that uses millions of microscopic radioactive beads, known as microspheres, to help destroy tumors from the inside out. By using this minimally invasive form of radiation, SIRT allows us to treat cancer that has spread to other parts of the body and cannot be treated surgically. Plus, SIRT can be used first, alone or in combination with chemotherapy. It can effectively control liver cancer and qualify patients for liver resection –possibly improving outcomes. It also is used to treat metastatic colon cancer that has spread to the liver.

Through a clinical trial, Indiana University Health Goshen Center for Cancer Care was the first in the United States to offer SIRT as a first-line treatment option in patients with metastatic colon cancer to the liver. This study has consistently demonstrated that chemotherapy and SIRT, used in combination, are more effective than chemotherapy alone to fight cancer.

Benefits

• Treats cancers that don’t qualify for liver resection, or hard-to-reach tumors that were once untreatable.
• Targets radiation directly to the tumor to improve patient outcomes.
• Delivers 40 times more radiation than conventional treatments.
• Minimizes radiation to healthy, sensitive tissue and organs surrounding the liver.
• Requires fewer treatment visits due to precise, larger doses.
• Can be completed in as few as two treatments.
• Can be used alone or with chemotherapy to shrink tumors and qualify a patient for liver resection.

How SIRT works

During SIRT, millions of microspheres are embedded with the radioactive element, Yttrium-90. These microspheres are then administered into the cancer area through the hepatic artery, the main blood vessel to the liver. Acting much like a time-release pain pill, these spheres (one-third the diameter of a human hair) deliver 40 times more radiation to tumors than conventional therapy. Since the polymer beads are too large to enter the bloodstream, they lodge in the small blood vessels that feed the tumor. Once trapped, they eradicate the tumor over a period of weeks. Although the microspheres reduce the size of the liver tumor, the normal liver tissue remains relatively unaffected. This is important as healthy liver tissue is extremely sensitive to radiation, previously preventing effective treatment with traditional radiotherapy.

At IU Health Goshen Center for Cancer Care, we customize our SIRT treatment differently than anywhere else by creating a patient-specific treatment protocol. Using a medical internal radiation dosimetry (MIRD) program developed at our facility, we calculate the highest and safest dose of radiation to deliver to the tumors while sparing healthy liver tissue. We also use PET/CT scans liberally for assessment of disease and treatment response.

Other types of radionuclide therapy

Our radionuclide therapy program offers a wide range of treatments for various types of cancer, including for lymphoma, bone cancer, thyroid cancer and pancreatic cancer.

The most commonly used radionuclide therapy is the radioactive iodine treatment (RAI) of hyperactive thyroid glands (hyperthyroidism) and thyroid cancer. Radioactive iodine treatment of thyroid disorders at IU Health Goshen Center for Cancer Care is integrated in a comprehensive surgical oncology and endocrinology program.

Pain associated with cancer that has spread to the bone from prostate, breast, lung or other cancers can be effectively controlled with radionuclide therapies. Strontium-89 (Metastron) and Samarium-153 (Quadramet) are isotopes that accumulate in the bone, specifically at the tumor sites. These therapies are indicated when the cancer has spread throughout the bones and when traditional treatments fail to control the pain.

In addition, the Food and Drug Administration has approved a new class of medicines known as radioimmunotherapy agents for advanced lymphoma. The technique uses monoclonal antibodies loaded with therapeutic radioisotopes directed to specific cancers. Radioimmunotherapy is a promising new area of cancer treatment that combines the targeting power of monoclonal antibodies with the cell-killing ability of localized radiation. Yttrium-90 and I-131 labeled radioimmunotherapy agents (Zevalin and Bexxar) are offered at IU Health Goshen Center for Cancer Care.