Selective internal radiation therapy (SIRT)

Overview

SIRT with resin-containing microspheres is a reimbursable procedure in Switzerland. The text in the Swiss catalog (KLV), in which such procedures are listed, reads: “for inoperable liver tumors that are not amenable to chemotherapy and for which other local ablative therapies are not possible or have shown no effect”. This applies to all liver metastases or primary liver tumors at the University Hospital Zurich. In particular, patients in the late inoperable stage and after several lines of chemotherapy are presented to the interdisciplinary tumor board. In such cases, a comprehensive internal medicine / oncology assessment of the patient is required first. This assessment depends on the patient’s performance status, the identification of the primary, dominant location of the tumor in the liver, the identification of the last chemotherapy used and its possible interference with SIR therapy. Important prerequisites for the treatment of the patient with SIR therapy are above all intact liver function, i.e. the absence of ascites as a sign of advanced liver failure, an elevated bilirubin (1.5 times above normal values), a disturbed coagulation status, elevated transaminases and thrombocytopenia. The indication for SIRT is summarized below.

Indication for SIRT therapy

Indication

• Inoperable liver tumors that are refractory to chemotherapy and for which other local ablative procedures are not possible or have shown no benefit

Contraindication

• The patient has already received external radiotherapy of the liver (does not apply to stereotactic RT)
• Ascites in clinical liver failure
• Abnormal synthetic or excretory liver function tests (ASAT, ALAT 5x above normal, bilirubin > 35 mumol/l)
• Hepato-pulmonary shunt of more than 20% according to Tc-99m MAA scintigraphy
• Gastric juice, pancreas or intestine in Tc-99m-MAA scintigraphy
• Dominant extrahepatic disease

SIR therapy procedure

After a discussion with the patient about the procedure, the preparatory measures for SIR therapy are carried out. This outpatient preparation mainly concerns the angiographic planning of the therapy. Only after this angiographic preparation is the patient ready for SIR therapy, and the outpatient Y-90-based therapy itself can be planned and carried out. As a rule, there is a period of about 2 weeks between planning and therapy. After a 5-hour observation period in hospital, the patient can usually be discharged home. Follow-up care is carried out in close cooperation with the referring doctor and usually under his supervision.

Side effects

SIR therapy carried out by experienced doctors generally has very few side effects. Mild fever, capsule pain, nausea and fatigue over several days are frequently reported. Rare but obligatory complications that need to be discussed are, above all, migration of the microspheres via the gastric or duodenal arteries into the corresponding organs. This is very unpleasant for patients and leads to local ulceration. These rare but possible side effects are discussed with the patient at the first consultation.