A pilot series demonstrating fluorescence staining of laryngeal papilloma using 5-aminolevulinic acid

Photodynamic therapy for recurrent respiratory papillomatosis

BACKGROUND

Recurrent respiratory papillomatosis (RRP) is a benign condition of the mucosa of the upper aerodigestive tract. It is characterised by recurrent papillomatous lesions and is associated with human papillomavirus (HPV). Frequent recurrence and rapid papilloma growth are common and in part responsible for the onset of potentially life-threatening symptoms. Most patients afflicted by the condition will require repeated surgical treatments to maintain their airway, and these may result in scarring and voice problems. Photodynamic therapy introduces a light-sensitising agent, which is administered either orally or by injection. This substance (called a photo-sensitiser) is selectively retained in hyperplastic and neoplastic tissue, including papilloma. It is then activated by light of a specific wavelength and may be used as a sole or adjuvant treatment for RRP.

OBJECTIVES

To assess the effects of photodynamic therapy in the management of recurrent respiratory papillomatosis (RRP) in children and adults.

SEARCH METHODS

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; Cambridge Scientific Abstracts; ICTRP and additional sources for published and unpublished trials. The date of the search was 27 January 2014.

SELECTION CRITERIA

Randomised controlled trials utilising photodynamic therapy as sole or adjuvant therapy in participants of any age with proven RRP versus control intervention. Primary outcome measures were symptom improvement (respiratory distress/dyspnoea and voice quality), quality of life improvement and recurrence-free interval. Secondary outcomes included reduction in the frequency of surgical intervention, reduction in disease volume and adverse effects of treatment.  

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration. Meta-analysis was not possible and results are presented descriptively.

MAIN RESULTS

We included one trial with a total of 23 participants. This study was at high risk of bias. None of our primary outcomes and only one of our secondary outcomes (reduction in volume of disease, assessed endoscopically) was measured in the study. There was no significant difference between the groups (very low-quality evidence). Adverse effects reported included airway swelling requiring intubation in a child with severe RRP a few hours after photodynamic therapy.

AUTHORS' CONCLUSIONS

There is insufficient evidence from high-quality randomised controlled trials to determine whether photodynamic therapy alters the course of disease or provides an added benefit to surgery in patients with recurrent respiratory papillomatosis. Multicentre randomised controlled trials with appropriate sample sizes and long-term follow-up are required to evaluate whether photodynamic therapy is of benefit. Outcomes such as improvement in symptoms (respiratory function and voice quality) and quality of life should be measured in future trials.

[Laryngeal papillomatosis: etiology, diagnostics and therapy]

Papillomas are rare tumors that originate from the mucosa. They may appear in the nose, paranasal sinuses, oral cavity, larynx, trachea, or the skin. Papillomas are mainly asymptomatic and are therefore mostly diagnosed coincidentally. In contrast, laryngeal papillomatosis may cause stridor, dyspnoea, and hoarseness. A viral cause of the disease seems likely, especially human papilloma virus. Mechanical irritation is also a possible reason when the nose, oral cavity, or oropharynx is affected. All papillomas, independent of their origin, may recur, and have the possibility of malignant degeneration in common. The therapy of choice is complete surgical excision. Regarding laryngeal papillomatosis, laser vaporisation or excision using the CO(2)laser is recommended. Because retreatments using conventional modalities are frequently necessary, especially in the case of laryngeal papillomatosis, adjuvant therapies are applied with the aim of reducing the recurrence rate and prolonging the interval between treatments.

Multiphoton excitation fluorescence microscopy of 5-aminolevulinic acid induced fluorescence in experimental gliomas

BACKGROUND AND OBJECTIVE

The clinical usefulness of 5-ALA guided detection of tumor tissue has been demonstrated for a number of malignancies. However, current techniques of intraoperative detection of protoporphyrin IX fluorescence in situ do not offer subcellular resolution. Therefore, discrimination of non-specific 5-ALA induced fluorescence remains difficult.

MATERIALS AND METHODS

In this study we have used an orthotopic glioma model to analyze PpIX fluorescence in tumor tissue and normal brain by multiphoton excitation microscopy after intraperitoneal administration of 5-ALA. A DermaInspect in vivo imaging system was used for autofluorescence measurements at 750 nm excitation and detection in the green channel of a standard photomultiplier module. For detection of PpIX fluorescence at different excitation wavelengths a red sensitive version of the photomultiplier and a filter combination of short pass filters and a color glass long pass filter was used restricting the sensitivity in the red channel to a range of 580-700 nm.

RESULTS

Multiphoton microscopy allowed a higher structural definition of tumor tissue based on the excitation of 5-ALA induced PpIX fluorescence compared to autofluorescence imaging. The high resolution of multiphoton microscopy allowed discrimination of fluorescence from the cytoplasm of tumor cells and 5-ALA induced PpIX fluorescence of normal brain parenchyma adjacent to tumor. Fluorescence lifetime imaging showed significantly longer fluorescence lifetimes of 5-ALA induced PpIX fluorescence in tumor tissue compared to normal brain. This allowed definition and visualization of the tumor/brain interface based on this parameter alone.

CONCLUSION

Multiphoton microscopy of 5-ALA induced PpIX fluorescence in brain tumor tissue conceptually provides a high resolution diagnostic tool, which in addition to structural information may also provide photochemical/functional information.

Indirect fluorescence laryngoscopy in the diagnosis of precancerous and cancerous laryngeal lesions

Indirect fluorescence endoscopy of the larynx has proven to facilitate the detection and delineation of precancerous and cancerous lesion. The different methods are easy to handle and can be performed on an outpatient basis. Early diagnosis of laryngeal cancer and its precursor lesions is simplified. The aim of the present study is to compare indirect autofluorescence laryngoscopy to 5-ALA-induced PPIX fluorescence laryngoscopy. In a prospective study, 56 patients with suspected precancerous or cancerous lesions were primarily investigated by indirect autofluorescence laryngoscopy. In a second step 5-ALA-NaCl (0.6%) was topically applied to the larynx by inhalation, and indirect fluorescence laryngoscopy repeated 2 h after application. Autofluorescence as well as 5-ALA-induced fluorescence was induced by filtered light (375-440 nm) of a xenon short arc lamp and processed by a CCD camera system (D-light-AF System, Storz, Tuttlingen, Germany). White-light and fluorescence images were digitally recorded, immediately assessed for diagnosis and finally compared to pathohistological findings. Inconspicuous laryngeal mucosa presented a typical green fluorescence signal in autofluorescence endoscopy, which turned blue during 5-ALA-laryngoscopy. Precancerous and cancerous lesions displayed a loss of autofluorescence in autofluorescence endoscopy whereas increased protoporphyrin IX fluorescence could be observed in 5-ALA laryngoscopy. Both imaging techniques were suitable to distinguish benign from precancerous or cancerous lesions. In contrast PPIX fluorescence was easily recognized in scarred vocal folds. According to our results, both non-invasive fluorescence imaging techniques are useful in the early diagnosis of laryngeal cancer. Moreover autofluorescence can be used immediately without drug application and possible side effects. 5-ALA-induced fluorescence seems to be more suited for diagnostic examination of mucosal lesions in recurrent precancerous and cancerous lesions after surgery.

Nuclear distribution of porphobilinogen deaminase (PBGD) in glioma cells: a regulatory role in cancer transformation?

Recently, considerable interest has been directed to red-fluorescence photodiagnosis of brain and other tumours during surgery using the protoporphyrin IX natural precursor, 5-aminolaevulinic acid. In the present study we focused on the role of the rate-limiting enzyme porphobilinogen deaminase in glioma C6 cell activity, differentiation and sub-cellular distribution. Over-expression of the human housekeeping porphobilinogen deaminase in the glioma cells, using the housekeeping-porphobilinogen deaminase plasmid, induced a G1 cell cycle attenuation accompanied by increases in enzyme activity and c6 differentiation toward astrocytes. Visualisation of subcellular localisation of the porphobilinogen deaminase using the independent techniques of fluorescence immuno-staining with specific anti-human porphobilinogen deaminase antibodies and cellular expression of porphobilinogen deaminase fused to green fluorescent protein, revealed (unexpectedly) a major fraction of porphobilinogen deaminase in the nucleus and only a minor fraction in the cytoplasm. Both C and N terminals of porphobilinogen deaminase fused to green fluorescent protein revealed a major fraction of the newly synthesized fused porphobilinogen deaminase in the nucleus. Furthermore, newborn rat brain cells grown in a primary culture showed the same localisation pattern of porphobilinogen deaminase in the nuclei. Stimulation of C6 glioma cell differentiation by butyrate induced a marked decrease in porphobilinogen deaminase both in the nucleus and in the cytoplasm as determined by Western blotting and fluorescence immuno-localisation. These findings suggest a possible dual role for housekeeping porphobilinogen deaminase in fast dividing glioma cells, one related to the porphyrin synthesis pathway and another coupled to nuclear function, which might be linked to tumorigenesis.

Fluorescence staining of oral cancer using a topical application of 5-aminolevulinic acid: fluorescence microscopic studies

INTRODUCTION

Topical application of 5-aminolevulinic acid (5-ALA) by means of a rinsing solution has been shown to be a promising new procedure in the diagnosis of oral malignancies. However, for assessing the reliability of this method regarding fluorescence-guided tumor resections and photodynamic therapy, further information on the distribution and penetration depth of 5-ALA-induced protoporphyrin IX (PPIX) in the tissue is needed.

METHODS

24 patients suffering from oral cancer were included in this investigation. Biopsies were taken immediately after fluorescence examination and either used as native sections for immediate fluorescence microscopic examination (n = 3) or shock frozen in liquid nitrogen and prepared as frozen sections (n = 46). Fluorescence imaging and digital image processing were utilized in order to determine the presence of PPIX in regions of various histologies as well as the penetration depth of PPIX into solid tumor.

RESULTS

PPIX fluorescence in the tissue was limited to the epithelium. Both normal and dysplastic epithelium showed PPIX fluorescence. In the stroma, no PPIX fluorescence was found. In some cases (n = 3/4) invasive carcinomas did not show PPIX fluorescence, while the adjacent or overlying normal epithelium was strongly fluorescent. The penetration depth of PPIX after topical application of 5-ALA was found to be limited to less than 1 mm.

CONCLUSION

PPIX fluorescence induced by topical application of 5-ALA can be very useful in the determination of superficial tumor margins. However, due to the limited penetration depth there is a risk of not accurately recognizing the infiltration depth of solid tumors. The aim of further investigations will be to assess the tissue distribution and depth of penetration of PPIX following systemic application of 5-ALA.