Cancer cells can be killed by exposing their DNA to electrons released when X-rays strike iodine-carrying nanoparticles, researchers have announced. The technique harnesses a phenomenon from quantum physics to take radiation therapy deeper into tumors, potentially making it effective against a wider range of cancers.
Charlatans and pseudo-scientists (not to mention bad science-fiction writers) love to say “quantum” a lot to give whatever they are selling a veneer for scientific credibility. Actual quantum behavior is so mind-bending it has sadly become a cover for all sorts of fakery, including false cancer “cures” that do nothing other than enrich the “healer” and delay patients getting treatment that might work.
So when the words quantum and cancer are used together it is wise to be suspicious. However, a new method for killing tumors is different. For one thing, it has been announced in the peer-reviewed journal Scientific Reports by a team from Kyoto University. For another, it relies on the photoelectric effect, the phenomenon known since 1887 and whose explanation by Einstein in 1905 helped start the whole quantum revolution.
"Exposing a metal to light leads to the release of electrons,” said Professor Fuyuhiko Tamanoi in a statement. "Our research provides evidence that suggests it is possible to reproduce this effect inside cancer cells."
Patients hearing about radiation therapy may imagine they are receiving a beam powerful enough to break the DNA of the cancer cells, but the method is frequently less direct. Often X-rays are used to produce free radical molecules that damage the cancerous cells' DNA. The free radicals require the presence of oxygen to form, and if blood vessels do not go deep enough into the tumor there may not be enough oxygen at its heart to produce the desired effect.
Researchers are seeking to bypass the need for oxygen. Some have shown potential in loading porous organosilica nanoparticles with gadolinium and injecting them into tissues or living animals. When exposed to X-rays the gadolinium releases electrons that tear through the DNA of the cancerous cells, killing them.
Gadolinium is so rare and obscure, few aside from professional chemists and those who have chosen to memorize the periodic table even know it exists. It also requires high-energy X-rays to release electrons, so encouraged by the proof-of-principle, Tamanoi's team went looking for something more suitable.
The paper reveals they have found it in the more familiar iodine. Instead of gadolinium's 50.25 keV X-Rays iodine works best at precisely 33.2 keV, which can be produced by more practically-sized generators. The viability of the approach has yet to be demonstrated in mice, let alone humans, but 3D tissues containing cancer cells 30 minutes of radiation was enough to kill the cancers within three days.
The process works because the cancer cells take up the nanoparticles more than healthy cells do, and even helpfully position them near the nucleus.
"Our study represents an important example of employing a quantum physics phenomenon inside a cancer cell," said co-author Kotaro Matsumoto. "It appears that a cloud of low-energy electrons is generated close to DNA, causing double strand breaks that are difficult to repair, eventually leading to programmed cell death."
Animal tests are now planned, as well as investigating how to get the iodine to attach to the DNA, rather than simply being nearby.