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.
Ascencio
Manuel
M
Department of Gynaecology and Obstetrics, Lille University Hospital, 59037 Lille Cedex, France.
Estevez
Juan Pablo
JP
Delemer
Marie
M
Farine
Marie Odile
MO
Collinet
Pierre
P
Mordon
Serge
S
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