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The management of head and neck mucosal dysplasia and microinvasive carcinoma is an appealing strategy to prevent the development of invasive carcinomas. While surgery remains the standard of care, photodynamic therapy (PDT) offers several advantages including the ability to provide superficial yet wide field mucosal ablative treatment. This is particularly attractive where defining the extent of the dysplasia can be difficult. PDT can also retreat the mucosa without any cumulative fibrotic complications affecting function. To date, clinical experience suggests that this treatment approach can be effective in obtaining a complete response for the treated lesion but long term follow-up is limited. Further research efforts are needed to define not only the risk of malignant transformation with PDT but also to develop site specific treatment recommendations that include the fluence, fluence rate and light delivery technique., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: The photosensitizer pro-drug 5-aminolevulinic acid (5-ALA) has been administered systemically for photodynamic therapy. Although several toxicities have been reported, nephrotoxicity has never been observed., Materials and Methods: Patients with head and neck mucosal dysplasia have been treated on a phase 1 study of escalating light doses in combination with 60mg/kg of oral 5-ALA. Serum creatinine was measured with the modified Jaffe method or an enzymatic method in the first 24h after 5-ALA. Interference by 5-ALA, as well as by its photosensitizing product protoporphyrin IX, was assessed., Results: Among 11 subjects enrolled to date, 9 of 11 had blood chemistries collected within the first 5h with 7 demonstrating significant grade 3 creatinine elevations (p=0.030). There was no additional evidence of compromised renal function or increased PDT-induced mucositis. Creatinine levels measured by the Jaffe assay increased linearly as a function of the ex vivo addition of ALA (p<0.0001). The exogenous addition of PpIX did not alter creatinine levels. ALA did not interfere with creatinine levels as measured by an enzymatic assay. A total of 4 of the 11 subjects had creatinine levels prospectively measured by both the Jaffe and the enzymatic assays. Only the Jaffe method demonstrated significant elevations as a function of time after ALA administration., Conclusions: The transient increase in creatinine after systematic ALA can be attributed, in part, if not entirely, to interference of ALA in the Jaffe reaction. Alternative assays should be employed in situations calling for monitoring of kidney function after systemic ALA., (Copyright © 2010 Elsevier B.V. All rights reserved.)