Yttrium-90 Microspheres

Yttrium-90 microspheres are a cutting-edge treatment for liver cancer, particularly hepatocellular carcinoma (HCC) and metastatic colorectal cancer. These tiny, radioactive beads are delivered directly to liver tumours, providing targeted radiation therapy. This treatment form is called Selective Internal Radiation Therapy (SIRT) or radioembolisation.

Mechanism of Action

Yttrium-90 is a beta-emitting radioisotope chosen for its ability to deliver high-energy radiation over a short distance, thus maximising tumour cell kill while sparing surrounding healthy tissue. The microspheres, typically made from glass or resin, are infused into the liver’s arterial supply. Since liver tumours derive most of their blood supply from the hepatic artery, while the portal vein predominantly feeds normal liver tissue, this allows for a highly targeted delivery of radiation.

Once administered, the microspheres become lodged in the small blood vessels feeding the tumour. The emitted beta particles then irradiate the tumour tissue, causing DNA damage that leads to cancer cell death. The radiation has a limited range of just a few millimetres, which helps to minimise collateral damage to healthy liver tissue.

Clinical Applications

Yttrium-90 microspheres are primarily used in patients with inoperable liver tumours. For patients with hepatocellular carcinoma who are not candidates for surgical resection or transplantation, SIRT offers a valuable treatment option. It is also utilised in treating liver metastases from colorectal cancer, especially when conventional chemotherapy fails to control the disease.

Clinical studies have shown that SIRT can effectively reduce tumour size, delay disease progression, and sometimes convert previously inoperable tumours to operable ones. Additionally, this therapy has been shown to improve survival rates and quality of life in patients with advanced liver cancer.

Administration and Dosage

The administration of yttrium-90 microspheres is a minimally invasive procedure performed by an interventional radiologist. The microspheres are delivered via a catheter inserted into the femoral artery and guided to the hepatic artery. The dose of yttrium-90 is carefully calculated based on the size and number of tumours and the patient’s overall liver function.

Safety and Side Effects

While yttrium-90 microspheres are generally well-tolerated, patients may experience side effects such as fatigue, abdominal pain, nausea, and fever. Rare but serious complications can include radiation-induced liver disease, gastrointestinal ulceration, and infection. Thus, careful patient selection and monitoring are essential.

Conclusion

Yttrium-90 microspheres represent a significant advancement in the treatment of liver cancer. By delivering high doses of radiation directly to tumours, SIRT offers a targeted approach that can effectively manage inoperable liver cancers, improve survival rates, and enhance patients’ quality of life. As research continues, the potential applications and efficacy of yttrium-90 microspheres are likely to expand, offering new hope for patients with liver cancer.

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