Radioactive Isotope Seed Offers Aggressive Option for Treatment Of Prostate Cancer

Richland, WA - Radioactive "seeds" have been used to cure thousands of cases of prostate cancer since first used some 40 years ago.

IsoRay Medical, Inc. is producing a powerful new kind of radioactive, cancer-destroying isotope seed made from Cesium-131 that is implanted directly into tumors.

Cesium-131 delivers its therapeutic radiation faster than other isotope seeds now being used and at reduced risk to patients when compared to surgery. Introduced in September 2004, the clinical use of cesium-131 marks the biggest advancement in seed brachytherapy (the Greek prefix brachy means short or close) since the introduction of palladium-103 19 years ago.

The Food and Drug Administration (FDA) approved Cesium-131 for marketing in March 2003. Its initial use has focused on prostate cancer, but it is approved for other malignant cancers, including head, neck, breast, brain, and liver cancers.

Patients at leading cancer treatment hospitals and clinics across the United States are now receiving Cesium-131. The centers for Medicare and Medicaid Services have established a specific reimbursement code for Cesium-131, and most insurance companies also cover the cost of the brachytherapy procedure.

Cesium-131 differs from other brachytherapy treatments in several ways:

• Faster acting -- It delivers 90% of the therapeutic radiation in just 33 days, compared to 58 days for Palladium-103 and 204 days for Iodine-125, resulting in a fast and aggressive radiation treatment plan to destroy the cancer cells before they have a chance to reproduce.
• Reduces the chances of normal tissue damage -- Cesium-131 has a 9.7 day half-life, compared to 60 days for Iodine-125 and 17 days for Palladium-103, that delivers significantly less total radiation to the patient. This reduces or eliminates any damage to healthy surrounding tissue from the effects of lingering radiation and significantly reduces the patient's exposure to prolonged and unnecessary periods of radiation.
• Better tumor penetration -- The energy level of the isotope is 29 KeV, which provides more than 30% greater penetration of the cancerous tissue than Palladium-103.
• Efficient and effective capsule design -- The seed is created by chemically attaching Cesium-131 to an inert material placed inside a 4.5 mm x 0.8 mm biocompatible titanium capsule. It provides a more predictable field of radiation that eliminates or reduces "hot/cold spots" and further reduces the potential for cancer cell survival and tumor recurrence.

Lane A. Bray, chief chemist of IsoRay Medical, Inc. and brachytherapy treatment pioneer, Donald C. Lawrence, who founded IsoRay Medical in Richland, WA in 1998, developed the Cesium-131 seed. Mr. Lawrence first created cancer-destroying radioactive seeds in the early 1960s. He was a longtime proponent of using Cesium-131 instead of other radioactive medical isotopes, but scientific and economic considerations prevented its commercial development until now.

The treatment of prostate cancer is an obvious first application for IsoRay Medical's Cesium-131 technology. Seed therapy is a proven and common treatment for this form of cancer, with 50,000 to 60,000 procedures conducted each year.

Also known as low-dose radiation (LDR), seed brachytherapy has a proven high cure rate in prostate cancer patients, particularly in early stages of the disease (T1 and T2 prostate cancer).

A seed brachytherapy procedure involves the use of special needles to implant the seeds, which are smaller than a grain of rice, using ultrasound guidance. The implant procedure is fast and convenient and the patient typically returns to normal daily activities within two to three days. Recently published clinical data shows that patient outcomes for seed brachytherapy surpasses those for radical prostatectomy and external beam radiation at far less cost while providing patients with a higher quality of life.

SOURCE: IsoRay