Boron neutron capture therapeutics

Boron Neutron Capture Therapeutics

Boron-10 neutron capture scheme

Boron Neutron Capture Therapeutics (BNCT) is a type of radiation therapy that targets cancer cells with high precision. It is based on the nuclear reaction that occurs when the stable isotope boron-10 captures low-energy neutrons, resulting in a highly localized release of alpha particles and lithium nuclei. These particles have a very short range, typically less than the diameter of a single cell, allowing for targeted destruction of cancerous cells while sparing surrounding healthy tissue.

Mechanism of Action

The principle of BNCT involves the selective delivery of boron-10 to tumor cells, followed by irradiation with thermal neutrons. The nuclear reaction is as follows:

\[ ^{10}B + n \rightarrow ^{11}B^* \rightarrow ^{4}He + ^{7}Li + 2.31 \text{ MeV} \]

The energy released in this reaction is deposited over a very short distance, effectively killing the cancer cells that have absorbed the boron compound.

Boron Delivery Agents

The success of BNCT depends on the development of effective boron delivery agents that can selectively accumulate in tumor cells. Two of the most studied compounds are sodium borocaptate (BSH) and boronophenylalanine (BPA).

Sodium Borocaptate (BSH)

Synthesis of sodium decahydrodecaborate

Schemes showing synthetic routes to BSH

BSH is a boron-containing compound that has been used in clinical trials for BNCT. It is known for its ability to penetrate tumor cells and deliver boron-10 effectively. The synthesis of BSH involves the reaction of decaborane with sodium hydroxide, resulting in the formation of sodium decahydrodecaborate.

Boronophenylalanine (BPA)

Synthetic route to BPA

BPA is another boron delivery agent that has shown promise in BNCT. It is an amino acid derivative that is preferentially taken up by tumor cells due to their increased metabolic activity. BPA is often used in combination with a positron emission tomography (PET) scan to assess its uptake in tumors before neutron irradiation.

Clinical Applications

BNCT has been primarily investigated for the treatment of glioblastoma multiforme, a highly aggressive type of brain tumor, and recurrent head and neck cancer. The ability of BNCT to selectively target tumor cells makes it a promising option for these difficult-to-treat cancers.

Advantages and Challenges

BNCT offers several advantages, including the potential for high selectivity and minimal damage to surrounding healthy tissue. However, challenges remain, such as the need for effective boron delivery agents and the availability of suitable neutron sources. Advances in nuclear reactor technology and the development of accelerator-based neutron sources are helping to address these challenges.

Related Pages

• Radiation therapy
• Neutron
• Cancer treatment
• Glioblastoma