Human melanoma treated by boron neutron capture therapy: comparison of the clinical response with the predicted response.
OBJECTIVE
A patient with malignant melanoma on the left foot was treated by thermal neutron capture therapy using 10B-paraboronophenylalanine. We compared the actual (clinical) response with the predicted response estimated using our past experimental and clinical data, and discussed some problems to be overcome in the future.


METHODS
We adopted an intravenous drip infusion of the compound whereby 170 mg/kg of the drug was administered over 4-5 hours before neutron irradiation. The patient was then irradiated with thermal neutrons from the Musashi Reactor at a reactor power of 100 kW and a neutron flux of 1.0 x 10(9) n/cm2/s at the collimator surface. The total absorbed dose to the melanoma and the surrounding skin was calculated by multiplying the thermal neutron fluences by the conversion factor.


RESULTS
The total absorbed doses to the melanoma and the surrounding normal skin were calculated as 19.0 and 9.4 Gy, respectively. These absorbed doses were estimated at 33.5 and 14.2 RBE-Gy, respectively, assuming that the relative biological effectiveness (RBE) of the high LET radiations was 2.0 and that each component of the mixed radiation was simply additive. The melanoma showed marked regression with mild skin reaction (dry desquamation) a month after therapy, and finally disappeared 10 months after therapy. There were no no substantial side effects.


CONCLUSIONS
We concluded that the outcome of our calculated dose values agreed well with the clinical response and that their compatibility indicated considerable validity for our approach. However, there are still some problems-uncertainty concerning the 10B concentration in tumor and skin, determination of the total absorbed dose, and a single curative dose for malignant melanoma-to be overcome with regard to clinical use of this therapy.
Hiratsuka
J
J
Department of Radiology, Kawasaki Medical School, Kurashiki, Japan.
Fukuda
H
H
Kobayashi
T
T
Kanda
K
K
Honda
C
C
Ichihashi
M
M
Mishima
Y
Y
D000368:Aged; D000369:Aged, 80 and over; D001896:Boron Compounds / Q000008:administration & dosage / Q000627:therapeutic use; D016754:Boron Neutron Capture Therapy; D005260:Female; D005528:Foot / Q000528:radiation effects; D005534:Foot Diseases / Q000532:radiotherapy*; D005544:Forecasting; D006801:Humans; D007262:Infusions, Intravenous; D018499:Linear Energy Transfer; D008545:Melanoma / Q000532:radiotherapy*; D010649:Phenylalanine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000627:therapeutic use; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000627:therapeutic use; D011879:Radiotherapy Dosage; D012062:Relative Biological Effectiveness; D012074:Remission Induction; D015203:Reproducibility of Results; D012867:Skin / Q000528:radiation effects; D012878:Skin Neoplasms / Q000532:radiotherapy*; D013819:Thermoluminescent Dosimetry; D016896:Treatment Outcome
D001896:Boron Compounds; D011838:Radiation-Sensitizing Agents; D010649:Phenylalanine; C033685:4-boronophenylalanine