Comparison of continuous and fractionated illumination during hexaminolaevulinate-photodynamic therapy.
OBJECTIVE
This experimental study aimed to compare continuous and fractionated illumination to optimize hexaminolaevulinate (HAL)-photodynamic therapy (PDT) in a rat tumour model with advanced ovarian cancer.


METHODS
Intraperitoneal 10(6) Nu Tu-19 cells were injected in 36 female rats Fisher 344. Peritoneal carcinomatosis was obtained 26 days post-tumour induction. Four hours post-intraperitoneal HAL (Photocure ASA, Oslo, Norway) injection, two schemes of PDT were performed at 30 mW cm(-2) on a 1cm(2) area: fractionated illumination (n=16) with a on-off cycle ("on": 2 min and "off": 1 min) until a fluence of 30 J cm(-2) was delivered, and continuous illumination (n=20) with a fluence of 45 J cm(-2). Laser light was generated using a 532 nm KTP laser (Laser Quantum, Stockport, UK). Biopsies were taken 24h after treatment. Semi-quantitative histology was performed. Necrosis value was determined-0: no necrosis to 4: full necrosis.


RESULTS
HAL-PDT was efficient in producing necrosis irrespective of the scheme (NV=3.34+/-0.91). Tumour destruction was superior with fractionated illumination compared to continuous illumination (3.67+/-0.70 vs. 3.10+/-0.94) (p<0.05).


CONCLUSIONS
Fractionated illumination during photodynamic therapy was shown to improve tumour response. Fractionated illumination with short intervals should be considered for an effective PDT of advanced ovarian cancer.
Department of Gynaecology and Obstetrics, Lille University Hospital, 59037 Lille Cedex, France.
Manuel
M
Ascencio
Juan Pablo
JP
Estevez
Marie
M
Delemer
Marie Odile
MO
Farine
Pierre
P
Collinet
Serge
S
Mordon
D000622:Aminolevulinic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D008027:Light; D009367:Neoplasm Staging; D010051:Ovarian Neoplasms / Q000188:drug therapy*; D010537:Peritoneum / Q000473:pathology* / Q000503:physiopathology; D010778:Photochemotherapy; D051381:Rats
D000622:Aminolevulinic Acid; C419924:5-aminolevulinic acid hexyl ester