Selective Internal Radiation Therapy (SIRT) is a treatment for liver cancers or tumours that delivers millions of tiny radioactive microspheres or beads called SIR-Spheres® directly to the liver tumours.
SIR-Spheres® are about one third the diameter of a strand of hair in size and they release a type of radiation energy called ‘Beta’ radiation. Beta radiation is a common type of radiation used in other nuclear medicine therapy and diagnostic procedures.
SIR-Spheres® are approved for the treatment of liver tumours that cannot be removed by surgery. These may be tumours that start in the liver (also known as primary liver cancer), or they may be tumours that have spread to the liver from another part of the body (also known as secondary liver cancer or metastases).
To perform SIRT, a small puncture or incision is made in the groin and a small thin tube called a catheter is placed in the artery and guided into the liver using X-ray pictures or images. SIR-Spheres® are delivered through the catheter and are then carried by the bloodstream directly to the tumours in the liver where they only lodge in the small vessels feeding the tumour.
The majority of SIR-Spheres® are lodged in the outside edge of the tumour/s and the radiation has a direct destructive effect on the tumour itself and the vessels feeding the tumour. Destroying the vessels feeding the tumour means that the tumour/s can no longer be supplied with the nutrients in the bloodstream. Most patients after SIRT will see a reduction or stabilisation of their liver tumours.
Neuroendocrine Neoplasms (NENs) present complex challenges to diagnosis and treatment. Even in metastatic cases spreading to the liver, there are some important differences compared to the more common types of gastrointestinal tumours and pancreatic adenocarcinomas, e.g. their sometimes-indolent nature and their ability to oversecrete hormones causing distinct clinical syndromes. Also, the tumours are known to be highly vascular which is a feature where growth inhibition and symptom relief may be achieved by specific 'blocking' agents - this is particularly the case with liver metastases in well-differentiated Neuroendocrine Tumours (NETs).Spread to the liver may occur from NETs of the foregut, midgut as well as hindgut. NET metastases are usually multiple and of varying size. In most cases, both liver lobes are affected, but widespread (miliary) seeding throughout the liver is seen…