Transforming radioactive strontium-90 into life-saving yttrium-90 for targeted cancer treatment
In the ongoing battle against cancer, medical science continually turns to nature's most fundamental forces—even those originating from the heart of nuclear reactors. For decades, strontium-90 (Sr-90), a radioactive byproduct of nuclear fission, was viewed primarily as a component of hazardous nuclear waste. Today, through remarkable scientific innovation, this same material has become the source of yttrium-90 (Y-90), one of nuclear medicine's most valuable tools for treating advanced cancers.
Nuclear fission byproduct with a 29-year half-life, traditionally considered hazardous waste
Medical radioisotope with a 64-hour half-life, used in targeted cancer therapies
The process of obtaining Y-90 from Sr-90 represents a fascinating alchemy that transforms environmental liability into medical miracle. This transformation provides life-saving therapies for patients with liver cancer, lymphoma, and other malignancies.
Yttrium-90 has earned its reputation as a therapeutic workhorse through a combination of ideal physical properties and relatively straightforward chemistry.
Trans-arterial radioembolization (TARE) delivers Y-90 microspheres directly to liver tumors
Success rate in treating hepatocellular carcinomaIn clinical practice, Y-90 is typically administered through trans-arterial radioembolization (TARE), where interventional radiologists inject millions of tiny glass or resin microspheres loaded with Y-90 into arteries supplying liver tumors 2 . Once lodged in the small vessels surrounding the tumor, these microspheres deliver a powerful radiation dose directly to the cancer cells.
The procedure has shown significant success in treating hepatocellular carcinoma (HCC), the most common form of liver cancer, particularly in patients with portal vein thrombosis where other treatments may be ineffective 7 . Studies have demonstrated that radioembolization with Y-90 significantly prolongs time-to-progression (TTP) of HCC and has a tolerable adverse event profile while improving patient quality of life 2 .
The story of Y-90 begins with its parent isotope, strontium-90, which is produced in substantial quantities as a fission product in both nuclear reactors and atomic weapons .
The central challenge lies in the chemical similarity of strontium and yttrium, which makes their separation technically demanding 4 . Medical applications require exceptional purity, with strontium-90 contamination kept below 10 μCi per Ci of Y-90 (approximately 1:100,000 ratio) to ensure patient safety 6 .
A groundbreaking 2025 study introduced a remarkably efficient one-step recovery process using commercially available sorbents 1 . This research addressed the challenge of developing a scalable separation method meeting stringent pharmacopoeia purity requirements 1 .
The research team evaluated three commercial sorbents for their ability to separate Y-90 from Sr-90 in solutions containing up to 10 GBq (approximately 0.27 Ci) of radioactivity 1 . This scale is clinically relevant, as typical therapeutic doses range from 1-4 GBq per procedure.
10 GBq of radioactivity tested, relevant for clinical applications
Researchers packed chromatography columns with three sorbents (TRU, DGA, and LN) separately. These sorbents use extraction chromatography, where the stationary phase selectively extracts specific elements from solution 1 .
Solutions containing both Sr-90 and its daughter product Y-90 were prepared and passed through the columns. The behavior of both elements was carefully monitored 1 .
Different eluting solutions selectively released captured Y-90 while leaving Sr-90 and other impurities bound to the sorbent. The eluted Y-90 was collected in fractions 1 .
Researchers employed sophisticated analytical techniques to determine both the recovery percentage of Y-90 and levels of radionuclidic impurities, particularly Sr-90 breakthrough 1 .
The study yielded clear results, with the TRU sorbent demonstrating superior performance for large-scale production of Y-90.
| Sorbent Type | Y-90 Yield | Suitability for Large-Scale Production | Key Advantages |
|---|---|---|---|
| TRU | ~80% | Excellent | Meets pharmacopoeia requirements even with chemically pure reagents |
| DGA | Not reported | Limited | Not suitable for the scale tested |
| LN | Not reported | Limited | Not suitable for the scale tested |
With an 80% recovery rate of Y-90 and compliant impurity levels, this one-step process simplifies traditional multi-stage separations 1 . The method maintains high purity with "chemically pure" reagents, potentially reducing production costs.
This methodology represents significant improvement over traditional approaches like solvent extraction using HDEHP, which often require multiple purification steps and more complex equipment 6 .
| Parameter | Requirement | Significance |
|---|---|---|
| Sr-90 Contamination | <10 μCi/Ci of Y-90 (at preparation time) | Prevents long-lived radioactive contamination in patients |
| Radionuclidic Purity | ≥99.998% | Ensures therapeutic effect comes primarily from Y-90 decay |
| Chemical Purity | Free of interfering metal ions | Enables efficient labeling of antibodies, peptides, and microspheres |
The separation and application of Y-90 in nuclear medicine relies on a specialized collection of chemical reagents and materials.
| Reagent/Material | Composition/Type | Function in Y-90 Production or Application |
|---|---|---|
| TRU Sorbent | Extraction chromatography resin | Selectively separates Y-90 from Sr-90 with high purity and yield |
| DGA Resin | N,N,N',N'-tetraoctyldiglycolamide | Extraction chromatography resin tested for Y-90/Sr-90 separation |
| HDEHP | Di-(2-ethylhexyl) phosphoric acid | Solvent extraction agent traditionally used for Y-90 separation |
| Cation Exchange Resin | Sulfonated polystyrene-divinylbenzene | Purifies Y-90 eluate and removes competing metal ions before labeling |
| DTPA | Diethylenetriaminepenta-acetic acid | Chelating agent used for conjugating with monoclonal antibodies for Y-90 labeling |
| Y-90 Microspheres | Glass or resin particles loaded with Y-90 | Delivery vehicles for selective internal radiation therapy (SIRT) of liver tumors |
These materials enable not only the production of pure Y-90 but also its incorporation into various pharmaceutical forms for different medical applications. The ongoing development and refinement of these tools continues to expand the potential uses of Y-90 in cancer therapy.
The successful development of efficient methods for obtaining Y-90 from Sr-90 represents more than just a technical achievement in radiochemistry—it embodies the transformative potential of turning hazardous waste into healing medicine.
The one-step separation process using TRU sorbent, with its impressive 80% yield and high purity output, marks a significant milestone in making this valuable therapeutic agent more accessible and potentially more affordable 1 .
Y-90 recovery rate with TRU sorbentAs research continues, we can anticipate further refinements in separation technology that may one day enable hospital-based generators similar to the technetium-99m generators commonly used today for diagnostic imaging.
The applications of Y-90 continue to expand beyond current uses in liver cancer, lymphoma, and arthritis treatment. Ongoing clinical trials are exploring combination therapies that pair Y-90 radioembolization with emerging treatments like immune checkpoint inhibitors and tyrosine kinase inhibitors 7 . Early results suggest that the local radiation from Y-90 may create a more favorable environment for these systemic therapies to work, potentially triggering beneficial immune responses against cancer cells throughout the body—a phenomenon known as the "abscopal effect" 7 .
The story of yttrium-90's journey from nuclear fission product to medical miracle illustrates how scientific ingenuity can find value in unexpected places. What was once considered merely a dangerous component of radioactive waste has become precisely targeted hope for cancer patients worldwide.