Local 5-aminolevulinic acid application for laser light-induced fluorescence diagnosis of early staged colon cancer in rats.
OBJECTIVE
5-Aminolevulinic acid (ALA) increases the intracellular accumulation of endogenous protoporphyrin IX in colon cancer. Protoporphyrin IX itself is a potential photosensitizer that can be used for laser light-induced fluorescence diagnosis. The aim of this study was to detect cancer in the rat colon before macroscopic visibility.


METHODS
Multifocal colon carcinomas were induced by weekly subcutaneous injections of 1,2-dimethylhydrazin-dihydrochloride in male Wistar rats. Local photosensitization was performed with an ALA colon lavage. Red fluorescence (635 nm) was induced by green laser-light irradiation with an Ar-Dye Laser (514 nm) in the colon. Fluorescence was observed by the naked eye with a filter at < 515 nm to eliminate the excitation light.


RESULTS
Twenty-five Wistar rats developed 99 macroscopically visible carcinomas and four macroscopically visible dysplasias. The following laser-light-induced fluorescence diagnosis procedure was able to detect 16 additional carcinomas and 41 additional dysplasias.


CONCLUSIONS
Local ALA application induces a tumor-specific protoporphyrin IX accumulation in the rat colon and is an efficient method for fluorescence detection of invisible dysplasias and early colon cancer in the rat.
Gahlen
J
J
Chirurgische Universitätsklinik Heidelberg, D-69120 Heidelberg, Germany.
Stern
J
J
Pressmar
J
J
Böhm
J
J
Holle
R
R
Herfarth
C
C
D019813:1,2-Dimethylhydrazine; D000622:Aminolevulinic Acid / Q000008:administration & dosage*; D000818:Animals; D014408:Biomarkers, Tumor; D003106:Colon / Q000473:pathology; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000175:diagnosis* / Q000378:metabolism; D003113:Colonoscopy; D005453:Fluorescence; D007834:Lasers; D008297:Male; D017319:Photosensitizing Agents / Q000008:administration & dosage*; D011237:Predictive Value of Tests; D011524:Protoporphyrins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D007507:Therapeutic Irrigation
D014408:Biomarkers, Tumor; D017319:Photosensitizing Agents; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D019813:1,2-Dimethylhydrazine