Yttrium Therapy: How It Works, Uses & Risks

What is Yttrium Therapy?

Yttrium therapy is a nuclear medicine treatment that uses the radioactive isotope Yttrium-90 (Y-90) to selectively irradiate and destroy cancer cells. Yttrium-90 is a beta emitter, meaning its radiation has a limited range within tissue, which helps to spare surrounding healthy structures. The therapy is primarily used in certain cancers when other treatment options are insufficient or unavailable.

Mechanism of Action

Yttrium-90 emits beta radiation during radioactive decay. This ionizing radiation damages the DNA of tumor cells, preventing them from dividing and ultimately causing cell death. Because the range of beta radiation in tissue is only a few millimeters, damage to surrounding healthy tissue is minimized.

For therapeutic use, Yttrium-90 is attached to carrier substances such as microspheres (tiny beads) or specific antibodies and peptides that deliver the radioactive material directly to the tumor site.

Areas of Application

Selective Internal Radiation Therapy (SIRT)

The most common application of yttrium therapy is Selective Internal Radiation Therapy (SIRT), also known as radioembolization. In this procedure, Yttrium-90-loaded microspheres are delivered via a catheter into the hepatic artery. The microspheres preferentially lodge in the blood vessels supplying the tumor and irradiate it from within. SIRT is mainly used for:

• Unresectable liver metastases (e.g., from colorectal cancer)
• Hepatocellular carcinoma (primary liver cancer)
• Other primary liver tumors

Radioimmunotherapy

In radioimmunotherapy, Yttrium-90 is conjugated to monoclonal antibodies that specifically bind to tumor cells. A well-known example is Ibritumomab tiuxetan (Zevalin), which is used for certain types of non-Hodgkin lymphoma.

Peptide Receptor Radionuclide Therapy (PRRT)

For neuroendocrine tumors, Yttrium-90 can also be coupled to peptides (e.g., octreotide analogues) that bind to specific receptors on tumor cells. This approach is known as Peptide Receptor Radionuclide Therapy (PRRT).

Procedure

Yttrium therapy is performed in specialized nuclear medicine centers or radiation oncology departments. Before treatment, comprehensive pre-assessments are conducted to evaluate patient suitability and to calculate the precise radiation dose. Administration varies by method:

• For SIRT: Microspheres are delivered via a catheter inserted at the groin (interventional radiology procedure)
• For radioimmunotherapy: Intravenous injection
• For PRRT: Intravenous infusion

Side Effects and Risks

As with any radiation-based treatment, yttrium therapy may cause side effects depending on the specific method and radiation dose. Possible side effects include:

• Post-embolization syndrome (with SIRT): fatigue, nausea, fever, and abdominal pain in the days following treatment
• Radiation-induced liver inflammation (radiation hepatitis)
• Bone marrow suppression (reduced blood cell production) with systemic applications
• Radiation pneumonitis (lung inflammation) if unintended lung exposure occurs

Careful patient selection and precise dosimetry are essential to minimize the risk of serious adverse events.

Advantages of Yttrium Therapy

• Targeted local irradiation with minimal systemic exposure
• Applicable even for inoperable or advanced tumors
• Can be combined with other cancer treatments (e.g., chemotherapy)
• Can be performed on an outpatient or short inpatient basis

References

1. Lencioni R. et al. - Radioembolization with Yttrium-90 microspheres in the treatment of hepatocellular carcinoma, Hepatology, 2012.
2. Witzig T.E. et al. - Randomized controlled trial of Yttrium-90-labeled ibritumomab tiuxetan radioimmunotherapy versus rituximab immunotherapy for patients with relapsed or refractory low-grade, follicular, or transformed B-cell non-Hodgkin lymphoma, Journal of Clinical Oncology, 2002.
3. Kwekkeboom D.J. et al. - Treatment with the radiolabeled somatostatin analog PRRT in patients with gastroenteropancreatic neuroendocrine tumors, Journal of Clinical Oncology, 2008.