Boron neutron capture therapy is a new cancer treatment technique that researchers hope will become a reliable alternative to surgery, chemotherapy, and radiation. The procedure involves injecting a cancerous tumor with high concentrations of boron isotopes, then subjecting the tumor to a beam of low-intensity neutrons. When neutrons penetrate boron atoms, a reaction occurs that emits a lithium ion and a high-energy alpha particle. The reaction destroys nearby cancerous cells while leaving healthy tissue unharmed. Boron neutron capture therapy is still in experimental stages, but it could become a mainstay of treatment in a few years or decades.
Isotopes of boron with ten neutrons are ideal for cancer therapy because they are non-radioactive and tend to seek out and bind with cancer cells. During boron neutron capture therapy, a concentrated solution of boron is administered through a vein in the arm or neck. Atoms travel in the bloodstream to the site of the tumor and attach to abnormal cells. Specialists can confirm that the boron is isolated to the tumor and not widespread in healthy tissue with fluorescent x-ray screenings.
Once boron is in place, a large neutron-emitting beam is pointed at the tumor. The beam emits neutrons at a controlled rate and slows them down significantly before they reach the patient. When a boron isotope picks up a neutron, it enters an unstable, excited state. An alpha particle is quickly emitted as a boron atom decays into lithium. The highly-charged alpha particle and lithium ion spread across a very short distance, about the width of a single cancer cell.
The high energy of the particles causes local cells to be obliterated. Cellular damage is limited to the tumor because the particles do not spread far enough to reach surrounding tissue. In clinical trials with animals and human volunteers, boron neutron capture therapy appears to be at least as effective as conventional radiation and chemotherapy on treating isolated brain tumors. Ongoing studies hope to determine if the procedure can be useful on tumors in other parts of the body as well.
Many researchers believe that boron neutron capture therapy will soon become a first-choice treatment option for patients with inoperable tumors. While chemotherapy and radiation are often successful, they can cause unwanted side effects. Radiation may affect healthy tissue in addition to cancerous tumors, and chemotherapy wreaks havoc on a patient's immune system defenses. Boron neutron capture therapy has the potential to eliminate both side effects. Ongoing research and clinical trials will likely continue for several years in order to perfect the technique before it is introduced in hospitals.