[Photodynamic diagnosis of neoplasms of the mouth cavity after local administration of 5-aminolevulinic acid].

BACKGROUND

The aim of photodynamic diagnosis (PDD) is the complete visualization of all neoplastic lesions in a tumorous organ after topical or systemic application of a tumor selective photosensitizer. In this investigation we performed semiquantitative fluorescence measurements following topical application of 5-aminolevulinic acid (5-ALA) in 11 patients with neoplastic lesions of the oral cavity.

METHODS

Time course and type of porphyrin accumulation were analyzed in neoplastic and surrounding normal tissue by measuring emission spectra of 5-ALA-induced protoporphyrin IX (PpIX) fluorescence at regular intervals for up to three hours following 15 min continuous rinsing of a 0.4% 5-ALA solution. After excitation with violet light of a high pressure xenon arc lamp (375-440 nm), fluorescence images in the red spectral range from the tumor tissue and the corresponding macroscopic visible tumor were recorded with a CCD camera. A quantitative analysis of the fluorescence contrast in neoplastic and surrounding tissue was performed using an optical multichannel analyzer.

RESULTS

PpIX fluorescence was detected in the oral mucosa of all patients after local application of 5-ALA. PpIX in neoplastic tissue accumulated earlier in comparison to the surrounding normal tissue. The fluorescence contrast between tumor and host tissue was 10:1 and the maximum fluorescence was measured 1-2 hours following 5-ALA application.

CONCLUSION

Labeling of mucosal lesions of the oral cavity with PpIX fluorescence induced by the local application of 5-ALA seems to be a promising diagnostic procedure for neoplastic lesions. Further investigations are required to assess the value of this new diagnostic procedure as a non-invasive and sensitive method for patients with head and neck cancer not only in pre- and postoperative diagnostic studies but also for a fluorescence-guided resection of tumors.