Clinical Studies Confirm: Not All Isotopes Are Created Equal
More and more physicians understand that not all isotopes are created equal, and their choice of isotope can make a difference in their patients’ recovery.
Higher Energy
Cesium-131, the isotope used in Proxcelan™ brachytherapy seeds has a higher average energy than any other commonly used prostate brachytherapy isotope on the market. Energy is a key factor in how uniformly the radiation dose can be delivered throughout the prostate. This is known as homogeneity. Early studies demonstrate that Cesium-131 is able to deliver the required dose while maintaining good homogeneity across the gland itself and potentially reducing unnecessary dose to critical structures such as the urethra and rectum.1
Shorter Half-Life
Cesium-131 has the shortest half-life of any prostate brachytherapy isotope at 9.7 days. Cesium-131 delivers 90% of the prescribed dose to the prostate in just 33 days compared to 58 days for Palladium-103 and 204 days for Iodine-125. The short half-life of Cs-131 reduces the duration of time during which the prostate receives the irritating effects of the radiation. Early studies demonstrate Cesium-131 is well tolerated with minimal to moderate urinary symptoms that resolve relatively rapidly, within approximately 4-8 weeks.1
Higher Biologically Effective Dose
Another benefit to the short half-life of Cesium-131 is what is known as the “biological effective dose” or BED. BED is a way for health care providers to predict how an isotope will perform against slow versus fast growing tumors. Studies have shown Cesium-131 is able to deliver a higher BED across a wide range of tumor types than either Iodine-125 or Palladium-103. Although prostate cancer is typically viewed as a slow growing cancer it can present with aggressive features. Cesium-131’s higher BED may be particularly beneficial in such situations.2
The Proxcelan™ brachytherapy seed (Cesium-131) is indicated for the treatment of malignant disease (e.g., head and neck, brain, breast, prostate, etc.) and may be used in surface, interstitial, and intracavitary applications for tumors with known radiosensitivity. The seeds may be used as a primary treatment or in conjunction with other treatment modalities, such as external beam radiation therapy, chemotherapy or as treatment for residual disease after excision of primary tumors.3
1. Prestidge B., Bice W., Jurkovic I., et al., “Cesium-131 Permanent Prostate Brachytherapy: An Initial Report”. Int. J. Radiation Oncology Biol. Phys. 2005; 63 (1): 5336-5337.
2. Armpilia CI., Dale RG., Coles IP., et al., “The determination of radiobiologically optimized half-lives for radionuclides used in permanent brachytherapy implants”, Int. J. Radiation Oncology Biol. Phys. 2003; 55 (2), 378-385.
3. Cesium-131 Brachytherapy Seed Product Labeling.
The Cesium-131 Advantage
- Patients reported mild to moderate symptoms with Proxcelan™ seeds.1
- Early urinary symptoms resolved rapidly, within 4-6 months with Proxcelan™ seeds in comparison to Iodine-125 seeds.1
1. Prestidge BR., Bice WS., "Clinical outcomes of a phase II, multiinstitutional Cesium-131 permanent prostate brachytherapy trial", Brachytherapy 6, 2007, 78.
