Minimally required heat doses for various tumour sizes in induction heating cancer therapy determined by computer simulation using experimental data.
OBJECTIVE
Although induction heating cancer therapy (IHCT) using magnetic nanoparticles can be a promising approach to treatment-less multi-nodular cancers, the objective requirement for successful clinical application has not clearly been elucidated. We intended to define objective heat doses suitable for IHCT, especially focusing on the sizes of liver cancer nodules.


METHODS
Alternating magnetic fields were applied to three human pancreatic cancer cell lines, the intercellular space of those cell pellets were filled with magnetic nanoparticles, and confirmed the cytotoxic effect of IHCT. Subsequently, the temperatures of liver cancer nodules in IHCT were simulated using a computer software program and the required heat dose for various sized tumours were determined.


RESULTS
Heating the cancer cells up to 50 degrees C for 10 min was sufficient for complete cell killing and the heat dose of 1.7 W/g(tumour) is required for 10 mm tumour. Larger tumours require a smaller heat dose, e.g. 20 mm and 40 mm tumours require 0.7 W/g(tumour) and 0.6 W/g(tumour), respectively, whereas smaller tumours require large amounts of heat, e.g. 5 mm and 1 mm tumours require 5.1 W/g(tumour) and 105 W/g(tumour), respectively.


CONCLUSIONS
Integrating the presently available technologies, including high-quality magnetic nanoparticles (1000 W/g(material)) and effective drug delivery systems (1-2 mg(material)/g(tumour)), treatment of a 10 mm tumour seems possible. Since treatment of smaller tumours less than 5 mm require substantial heat dose, researchers involved in IHCT should target cancer nodules of 10 mm or more, and develop a heat delivery system providing a minimum of 1.7 W/g(tumour).
Yamada
K
K
Department of Surgery, Advanced Biomedical Applications, University of Tsukuba, Ibaraki, Japan.
Oda
T
T
Hashimoto
S
S
Enomoto
T
T
Ohkohchi
N
N
Ikeda
H
H
Yanagihara
H
H
Kishimoto
M
M
Kita
E
E
Tasaki
A
A
Satake
M
M
Ikehata
Y
Y
Nagae
H
H
Nagano
I
I
Takagi
T
T
Kanamori
T
T
D045744:Cell Line, Tumor; D002470:Cell Survival; D003198:Computer Simulation; D003911:Dextrans; D052203:Ferrosoferric Oxide; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D008113:Liver Neoplasms / Q000556:secondary / Q000628:therapy; D008280:Magnetics; D058185:Magnetite Nanoparticles; D053758:Nanoparticles; D009369:Neoplasms / Q000628:therapy*; D010190:Pancreatic Neoplasms / Q000628:therapy
D003911:Dextrans; D058185:Magnetite Nanoparticles; C065507:ferumoxides; D052203:Ferrosoferric Oxide