Regression of melanoma xenografts by neutron capture therapy

Buck, S; Allen, BJ

Regression of melanoma xenografts by neutron capture therapy

Date

1989-09-22

Authors

Buck, S

Allen, BJ

Publisher

AINSE

Abstract

The development of Neutron Capture Therapy (NCT) offers advantages to conventional radiation therapy which is limited by the tolerance of surrounding healthy tissues within the treatment volume. NCT also eliminates the problems associated with radioisotope label led anti—tumour agents in that there is no initial radiation dose to whole body prior to selective tumour targeting, and no longer term background effect to normal tissues. NCT utilizes 10B (n, α) 7Li reaction in order to deposit short range (10—14μm) high linear Energy Transfer (LET) radiation of an average 2.4 MeV, within a tumour mass . The efficacy of this technique relies upon an adequate 10B distribution within the tumour, while maintaining pharmacologic selectivity of 10B to target tissues and adequate shielding of healthy tissues using a neutron absorbing material, 6LiF . An in vivo irradiation facility has been installed in the thermal column of the Moata reactor. Incident neutron flux is 10 10 n cm-2 s -l with concomitant gamma dose of 4.8 Gy h-l . Nude mice bearing human melanoma xenografts are anaesthetised and loaded into 6LiF epoxy cylinders under Specific Pathogen Free (SPF) conditions. Melanoma xenografts are located in the thigh and protrude from the cylinders; thus being exposed to the full neutron field. Healthy tissue is shielded, reducing the neutron flux to a few percent of the incident value. We have found there to be no problem associated with the concomitant whole body gamma dose within the range of exposure used for NCT. Irradiation follows i. p. or i. v. injection of 10B enriched p—borono—L—pheny1a1anine. Hcl. ( 10B/1—BPA.Hcl) at times when tumour/healthy tissue concentration ratios are optimal . Turnour size is monitored for volume changes following therapy; regression and growth delay indices are determined for different doses of 10B/ I—BPA.Hc1 and neutron fluence . These are compared with control growth curves, i e. (1) no irradiation (2) irradiation without 10 B/ I—BPA. Hcl pre—treatment.

Description

Physical copy held by ANSTO Library at DDC: 571.45/14

Keywords

Biological shielding, Boron compounds, Boron 10 target, Gamma radiation, In vivo, Lithium fluorides, Lithium 7, Lithium 7 reactions, Melanomas, Mice, MOATA Reactor, Neutron capture therapy, Neutron flux, Phenylalanine, Radiation doses

Citation

Buck, S., & Allen, B. J. (1989). Regression of melanoma xenografts by neutron capture therapy. Presentation to the 12th AINSE Radiation Biology Conference, 22-24th September 1989, Lucas Heights, (pp. 30). Lucas Heights, New South Wales : AINSE.