Background: Cancer of the oral cavity, oropharynx and larynx are the most common malignancies in the head and neck region. The prognosis for the patients concerned is highly dependent on an early detection and fast surgical treatment. Fluorescence guided examinations may serve as a possible diagnostic tool for better demarcation and delimitation of head and neck cancer. Therefore, the presented study was aimed at the detection of a selective Protoporphyrin IX (PPIX) accumulation in malignant oral, oropharyngeal and laryngeal lesions following topical and systemic application of 5-aminolevulinic acid (5-ALA).
Patients: We investigated 193 patients with suspected lesions in the oral cavity and oropharynx (n = 126) as well as in the larynx (n = 67). The patients received a varying dose (rinsing 200 mg, inhalation 30 mg, 2,5 - 25 mg/kg BW by mouth) of 5-ALA in aqueous solution. Both fluorescence pictures and macroscopic findings under white light were recorded using a target integrating, color CCD camera. Fluorescence contrasts between tumor and normal tissue were registered by an optical multichannel analyser.
Results: Our results have shown that after topical and systemic application of 5-ALA, PPIX fluorescence could be identified within the mucosa of the oral cavity, oropharynx and the larynx of all patients with a duration of up to 48 hours after systemic application. Malignant lesions usually showed higher intensities of PPIX-fluorescence than surrounding innocuous mucosa. A maximum fluorescence contrast between normal tissue and neoplastic lesions was observed at 1.5 hours after topical application and 3 hours after systemic application.
Conclusions: It will be the aim of further investigations to verify the optimal time of incubation and dosing of systemical 5-ALA application to enhance fluorescence contrasts and set the basis for fluorescence guided resections.