Rarest Element on Earth Could Be Used to Treat Cancer

And you probably have never heard of it before.

Have you ever heard of astatine?  Yeah, me neither.  Astatine is the rarest element on Earth, and it is also highly unstable and radioactive.  Its Greek name, astatos, literally means unstable.  The element is so rare that it is estimated that less than an ounce of it exists on the entire planet.

Although astatine has never been directly observed, it occurs naturally as a result of the decay of uranium and thorium.  In 1940, a group of researchers led by Dale Corson at the University of California, Berkeley, synthesized astatine for the first time by bombarding bismuth with alpha particles.  

Scientists are now able to create several isotopes of astatine, most importantly astatine-211.  Researchers from CERN, back in 2013 at their ISOLDE facility, used the Resonance Ionization Laser Ion Source to study the atomic structure of astatine for the first time.  They discovered that the element may have applications for targeted alpha therapy in cancer treatment.  

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Astatine has decay properties that make it an ideal candidate for a short-range radiation source to create radiopharmaceuticals, however it is difficult to research since it degrades so quickly. At its most stable, astatine has a half-life of only 8.1 hours, meaning every 8.1 hours half of your sample will have degraded until, eventually, you’ll have nothing left.

Similarly to iodine-131, which is currently used for cancer treatment, astatine-211 undergoes radioactive decay and tends to build up in the thyroid gland.  Unlike iodine-131, however, astatine-211 does not release beta-radiation.  Beta-radiation travels further into the body than alpha radiation, which causes damage not only to the cancer cells, but to the healthy cells that surround them.

Astatine-211 may be a more powerful isotope, since its very short half-life means the radiation exposure to patients would be lower than existing treatments.  It also tends to decay back into bismuth, a heavy metal with extremely low toxicity.

Duke University in North Carolina, conducted a very small but promising clinical trial testing astatine radiotherapy in 18 brain tumour patients.  The hope is, if astatine-211 is found to be a successful medicine, it will be used to treat several forms of cancer.  Earth’s rarest element might one day be very common in hospitals.