Boron neutron capture therapy (BNCT) is a targeted radiotherapy that uses boron-10 as a delivery agent and neutrons as a source. BNCT selectively kills cancer cells by the high linear energy transfer of alpha particles and lithium ions produced during the nuclear reaction of boron-10 with neutrons. Clinical trials of BNCT have shown effectiveness in treating brain tumors and recurrent head and neck cancers. Further research is still needed to develop more effective boron delivery agents and neutron sources to advance this promising cancer treatment technique.

2. Seminar
ATTIA FATIMA
Reg. No. 781
M.sc Chemistry 4th Semester

4. Boron Chemistry
Boronis the element of group13(IIIA), havingatomic number 5 and
atomic mass 10.811.
First,Boronwas mentioned in book of Persian alchemist Rhazes.
In 1892,French Chemist Henri Moissanproducedboronthat was 98%
pure.
The originof boronis attributedto Big Bang or galactic cosmic raysevents
as well as the formation of Li and Be.

6. Chemistry
It is a semiconductors,characteristicsof both metals and non metals.
The abundanceof boronis very low, approximately10-9times that of
hydrogenand around10-6 of carbon and oxygen.
Physicalproperties
It occurs in many physicalforms called allotropes.
Boronatoms are able to absorb a large number of neutrons.
Two typesof isotopesof boron exist,boron-10and boron-11.Three
radioactiveisotopesof boron are knownalso.

7. Chemistry
Chemical properties
Boronis not solublein water. It normally doesnot react with acidsbut react
withoxygenin the air.
Usesof boron
Boronis usedto make alloysand alloysare used to make strongmagnets.
Thesemagnets are used in microphones,loudspeakers,headphonesand
switches.
Boronused in nuclear rodsfor controllingthe fast moving neutrons.
Boronis provedto be used in cancer treatment,.Boron-10particularly.
Boronoccurs in many vegetables,fruits and in nuts.

8. Boron for Cancer
Boronis an element that has proved to be effectivein cancer treatment due
to its propertyto absorb the neutrons.
The therapythat is used againstcancer treatment is knownas Boron
NeutronCaptureTherapy.
What is cancer
Canceris caused by the rapidlydividingabnormal cells that have the
potentialto reproducethemselvesfaster than the normal cells.
Theserapidlydividingcells form tumors, crowd organsand shutdown
some organfunction.

9. History of Cancer
Lymphtheorydevelopedin 17th centurybelieved on abnormalitiesin
lymphaticsystemwere the cause of cancer.
In 19th centuryRudolphVirchow recognizedthat the cancerouscells
derivedfrom other cells.
Other theoriesdescribed,cancer beingcaused by the trauma, parasitesand it
was thoughtthat cancer may spread “like a liquid”.
Karl, a German surgeonconcludedthat cancer spread throughmalignant
cells.

11. Cancer and Heredity
Canceris diseaseof abnormal gene function.
About5% to 10% of all cancers are inherited..Genes that cause cancer
calledOncogenes.
Topten CancerMyths
Hair dyecause brain cancer
Cellphonescause cancer
If yourmom and dad had Cancer, youwill have it too
Cancercauses hair loss
Onlywomen get breast cancer
Canceris almost alwaysfatal
Wearingantiperspirantsand deodorantcan cause cancer
Some typesof cancer can be contagious
Positivethinkingwill cure cancer

12. Boron neutron Capture Therapy
BNCT is an ideal techniqueto kill cancer cells selectivelywithoutharming
cancer cells which is based on the reaction of non-radioactiveboron-10
nucleicapturingslow neutronsto yield high-LETalpha particles,recoiling
Li-7 and Gamma rays.
BNCTproposedto treat the patientsof glioblastomamultiforme (GBMs).
GBMsis a typeof malignanttumor of brain involvingthe glial cells.52%is
functionalbrain tissueand 20% intercrainialtumors.
Alsoshown its ability to treat other cancers,like neck cancer, liver cancer,
melanomas and thyroidcancers since the mid 1980s.

13. Basic principle
It is a targeted Chemo-radiotherapy.
Firsto all, a boron-10carryingdrug throughthe blood transportation
system.For successfulBNCT Bloodbrain barrier (BBB) is used,either by
passivetransportor throughthe receptor mediated transport..
Thermal neutrons(E=0.025eV)or an epithermal neutron(1eV<E<10keV)
usedas a source. Nuclear reactors are the source of neutrons.
Bythe decay of boronatom, Helium-4 nuclei(alpha particle) and Lithium-7
ionsto kill the tumor cells.

15. Boron neutron capture reaction formula (Walker, 1998)

16. Basic principle
He and Li, particle range within the tumor cells are 9um and 5um (diameter
of a tumor cells) respectively.
Theyhave a highlinear energytransfer (LET) valuesas well.Thus high
energyreleased in the tumor cell while normal cells outsidethe tumor cells
survive.
Figure shows the schematic concept of BNCT. (MIT, 2008)

19. Two Major factors of BNCT
1- Boron-10deliveryagents
2- Neutronssources
Boron-10deliveryagents
The primary factor for successfulBNCTrelies upon the boron-10delivery
agents.There are seven aspects shouldbe consideredfor a usefulboron-10
deliveryagent.
1-The important one is the selectiveaccumulative abilityto achieve high
ratiosof (conc.of boronin tumor cells/ conc. of boronin normal cells.

20. Two major factors of BNCT
2- Low or even nonesystematictoxicity
3-To achieveat least 20ug B10/gof tumor boron-10
4- Rapidclearance from bloodand normal tissuesand persistencein
tumor duringBNCT
5- Chemical stability
6-Water solubility
7- Lipophilicity

21. Names of delivery agents
1- BPA(4- dihydroxy-borylpheynlalanine)
2- Polyhedralboranes[ B10h10]-2 and [B12H12]-2
3- SodiumdecahydrodecaborateNa2B10H10.Itprovedto be toxicto the
human bodylater on.
4- FinallyBSH (sulfahydralborane,Na2B12H11SH)with lower toxicity
was developed.

22. Neutrons sources
Two typesof neutronsare used for BNCT
1-Thermal neutrons
2- Epithermal neutrons
ThermalNeutrons
Theyhave energiesof approximately0.025eVare used in BNCT.
Thermal neutronshowever cannotpenetrateinto deep intodeep tumors due
to only2.5cm penetrationrange of them within the tissuessurface.
Thusthermal neutronsare suitablefor superficialtumor treatments, such as
BNCTtreatment for melanoma which is typeof skin cancer.

23. Epithermal Neutrons
In order to effectivelytreatthe tumors deep inside the brain without
openingcrania.Epithermalneutronshave energies (1-10,000eV)
beams can deeplypenetratethe tissue 3-6cm below the surface.
So it can be used to treat deep inside the tumor cells.
At present, neutron beams are extracted from the uranium-
235 fission reaction within a nuclear reactor (Walker, 1998).

25. Clinical trials for cancer
treatment
BNCTtrials for brain tumors
At USA
BNCTwas initiallyproposedto deal with these brain cancers such as
glioblastomamultiforme (GBM).BNCTof patientswith brain tumors and a
few with cutaneousmelanoma was resumed in the unitedstatesin the mid
1990sat the BrookhavenNationalLaboratoryMedicalResearch Reactor
(BMRR)and at Harvard InstituteofTechnology(MIT) usingMITresearch
reactor (MITR).
The figure shown below is the CTscansof a patientwith GBM.In the right
handfigure shownGBM cells of spindleshaped.

27. Clinical Trials
At Japan
Miyatakeand Kawabata in Japan have initiatedseveral protocols
employingthe combination of BPA(500mg/kg)and BSH (100mg/kg)for
twohours,followedby neutron irradiationat Kyoto UniversityResearch
ReactorInstitute.
At Finland
The team of cliniciansand physicistat the HelsinkiUniversityCentral
HospitalandVTITechnical Research Central of Finlandhas reportedon 22
patientswith malignant gliomas who had undergonestandardof their
recurrenthead and neck cancers and brain tumors have been treated in
Finlandwith BNCT.

28. Conclusion
BNCT represents a joining together of nuclear technology, chemistry,
biology and medicine to treat malignant and recurrent head and neck
cancers. Sadly the lack of progress in developing more effective
treatment for these tumors has been part of the driving force that
continues to propel research in this field. BNCT may be best suited as an
adjunctive treatment, used in the combination and external beam
radiation therapy for those malignancies, either primary or recurrent, for
which thereare no effectivetherapies.