Enhancement of blood porphyrin emission intensity with aminolevulinic acid administration: a new concept for photodynamic diagnosis of early prostate cancer.

BACKGROUND: The objective of this paper was to verify if the oral administration of δ-aminolevulinic acid (ALA) in animals with prostate tumor can increase the sensitivity of cancer diagnosis by protoporphyrin IX blood autofluorescence. In this study, the autofluorescence of blood porphyrin was analyzed using fluorescence spectroscopy on healthy male NUDE mice and in those with prostate cancer induced by the inoculation of DU145 cells.
METHODS: A total of 18 male NUDE mice, ∼8 weeks old on arrival were divided into 3 groups: Control, Tumor and ALA Tumor. The autofluorescence of blood porphyrin of the groups was analyzed using fluorescence spectroscopy at different days after tumor induction, to monitor the tumor progression. Emission spectra were obtained by exciting the samples at 405 nm. The animals inoculated had their blood collected with and without oral ALA solution administration to compare PPIX endogenous (Tumor group) and exogenous (ALA Tumor group) signal intensity and to establish a method to diagnosis early prostate cancer.
RESULTS: Significant differences were observed in autofluorescence intensities measured in the 575-725 nm spectral regions for the studied groups.
CONCLUSIONS: The results showed an enhancement of almost 100% in blood PPIX fluorescence, using the oral administration of δ-aminolevulinic acid on male NUDE mice with prostate cancer, making fluorescence measurements more accurate and sensitive since the first week after tumor induction.