E. Endlicher et al., Endoscopic fluorescence detection of low and high grade dysplasia in Barrett's oesophagus using systemic or local 5-aminolaevulinic acid sensitisation, GUT, 48(3), 2001, pp. 314-319
Background and aims-Barrett's oesophagus is associated with an increased ri
sk of cancer. As dysplasia is not visible during routine endoscopy, random
biopsies in the four quadrants every 1-2 cm are recommended. Endoscopic flu
orescence detection (EFD) after sensitisation with 5-aminolaevulinic acid (
5-ALA) with different modes and concentrations was assessed to optimise the
technique for detection of dysplasia or early cancers. 5-ALA is converted
intracellularly to protoporphyrin IX which accumulates in malignant tissue
and can be detected by typical red fluorescence after illumination with blu
e light.
Methods-In 47 patients with Barrett's oesophagus, 10 with known dysplasia,
58 fluorescence endoscopies were performed after sensitisation with differe
nt concentrations of 5-ALA given orally (5, 10, 20, 30 mg/kg) or locally (5
00-1000 mg) by spraying the mucosa via a catheter. EFD was performed 4-6 ho
urs after systemic and 1-2 hours after local sensitisation using a special
light source delivering white or blue light. A total of 243 biopsies of red
fluorescent (n=113) and non-fluorescent areas (n=130) were taken.
Results-In three patients, two early cancers and dysplasia, not visible dur
ing routine endoscopy, were detected by EFD. Thirty three biopsies revealed
either low or high grade dysplasia. Sensitivity for detection of dysplasti
c lesions ranged from 60% after local sensitisation with 500 mg to 80%, 100
%, and 100% after systemic application of 5-ALA 10, 20, and 30 mg/kg, respe
ctively. However, specificity was best for local sensitisation (70%) while
systemic administration revealed values between 27% and 56%. Using 5 mg/kg,
no red fluorescence in dysplastic lesions was found. No severe side effect
s were noted.
Conclusion-EFD is a promising tool to detect non-visible dysplastic lesions
in Barrett's oesophagus using 5-ALA sensitisation. A randomised controlled
study is now indicated to compare the efficacy of EFD with the standard te
chnique of four quadrant random biopsies.