Therapy introduction | Heron Neutron Medical Corp.

BNCT

Boron Neutron
Capture Therapy

In Taiwan, cancer (malignant tumors) has been the first of the top ten causes of death in the past 40 years. With the advancement of medical technology, some cancers are no longer incurable. The development of new therapies such as targeted drugs, immunotherapy and various radiation therapies has saved many patients.

Boron Neutron Capture Therapy (BNCT) is not an emerging treatment. It has been developed for more than 70 years since it was first applied to clinical in the United States in the 1950s. In recent years, there have been advances in various particle accelerators and boron-containing drugs. Countries around the world have sprung up to study BNCT therapy. In addition to Japan's first successful approval of BNCT, the most notable is the clinical results and future development of BNCT in Taiwan.

The ratio of BPA uptake in tumors and normal tissues is 2 to 4 times.

Boron-containing drugs (e.g. BPA) are more likely to accumulate in cancer cells.

The structure of BPA is similar to the phenylalanine, an essential amino acid in the body, so it will be taken by cancer cells in large quantities.
BPA absorbs neutrons and is about three times more lethal to tumors than normal tissues.

After entering the body, super-thermal neutrons will decelerate into low-energy thermal neutrons and react with ¹⁰B to produce α and Li particles, which release energy at a distance smaller than the diameter of the cell. Compared to photons, this reaction is more lethal to cancer cells in terms of the CBE.
During radiation therapy, tumors receive about 9 times the boron dose than normal tissues.

The ratio of boron dose to normal tissue in the tumor is 9 times. If background dose is taken into account, the dose ratio between tumor and normal tissue is generally more than 5 times. In causing apoptosis of cancer cells by double stranded DNA breaks, normal cells are less affected.

BNCT Treatment Principle

BNCT is an in-vitro targeted radiation therapy. The isotope ¹⁰B of boron to interact with neutrons and release energy to kill tumor cells without seriously affecting normal cells. The treatment process of BNCT divided into two parts. First, accumulate the stable isotope ¹⁰B at the tumor site, and thermal neutrons (usually with an energy below 1 eV) irradiate the tumor site. Because the capture probability between thermal neutrons and ¹⁰B is much greater than that between thermal neutrons and the main components of the cell (carbon, hydrogen, oxygen, nitrogen). Most of the thermal neutrons irradiated at the tumor site easily react with ¹⁰B and quickly release high-energy ⁷Li and α particles. Since the maximum distance of ⁷Li and α particles in cells is only 4 μm and 9 μm, which is equivalent to the size of a cell. The damage of normal cells that destroyed by the high-energy particles generated from the reaction is relatively small.

1950's
First Application

The treatment which uses boron-containing drugs to accumulate in tumor cells and then use neutrons to trigger a radiation reaction, combines the advantages of targeted therapy and radiotherapy to achieve no harming the innocent. Boron neutron capture technology was first applied to clinical in the 1950s and was proposed by Massachusetts General Hospital (MGH) in United States for the treatment of malignant brain tumors.