[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.