Photodynamic therapy in oral cancer: a review of clinical studies

A significant mortality rate is associated with oral cancer, particularly in cases of late-stage diagnosis. Since the last decades, oral cancer survival rates have only gradually improved despite advances in treatment. This poor success rate is mainly due to the development of secondary tumors, local recurrence, and regional failure. Invasive treatments frequently have a negative impact on the aesthetic and functional outcomes of survivors. Novel approaches are thus needed to manage this deadly disease in light of these statistics. In photodynamic therapy (PDT), a light-sensitive medication called a photosensitizer is given first, followed by exposure to light of the proper wavelength that matches the absorbance band of the photosensitizer. The tissue oxygen-induced cytotoxic free radicals kill tumor cells directly, harm the microvascular structure, and cause inflammatory reactions at the targeted sites. In the case of early lesions, PDT can be used as a stand-alone therapy, and in the case of advanced lesions, it can be used as adjuvant therapy. The current review article discussed the uses of PDT in oral cancer therapy based on recent advances in this field.

Daylight photodynamic therapy for the management of actinic cheilitis

Early identification and adequate treatment of actinic cheilitis (AC), which affects the lower lip vermillion and is considered a precursor of squamous cell carcinoma, is mandatory. Photodynamic therapy (PDT) has been successfully used in AC. PDT with the use of daylight (DLPDT) is equally effective and more convenient than the conventional PDT. Data on short and long-term efficacy of DLPDT in AC are limited. Our primary purpose was to assess efficacy of DLPDT in AC as well as safety and tolerance. Twenty-two individuals with histologically confirmed AC received 2 MAL (5-aminolevulinic acid)-DLPDT sessions 1 week apart. Patients were evaluated clinically 3, 6, and 12 months after treatment. Non-complete responders were biopsied and excluded from the study if histological alterations were indicative of AC. Adverse events were recorded from baseline to the end of the 12-month follow-up period. Twenty patients completed the study. Overall, complete clinical response 12 months after treatment was 80% (16/20), while an association between treatment response and grade of dysplasia was observed (p = 0.016). With respect to response by grade, complete clinical response achieved in grade I AC was 100% (12/12) and 50% (4/8) in grade II AC. Main adverse events included mild erythema, oedema, and scaling, with no pain associated with DLPDT. According to our results, DLPDT seems to be of significant benefit for the treatment of grade I AC. Combination with the other treatment modalities could improve the efficacy in grade II AC. Further studies are needed for the assessment of late recurrences.

Platform for ergonomic intraoral photodynamic therapy using low-cost, modular 3D-printed components: Design, comfort and clinical evaluation

Oral cancer prevalence is increasing at an alarming rate worldwide, especially in developing countries which lack the medical infrastructure to manage it. For example, the oral cancer burden in India has been identified as a public health crisis. The high expense and logistical barriers to obtaining treatment with surgery, radiotherapy and chemotherapy often result in progression to unmanageable late stage disease with high morbidity. Even when curative, these approaches can be cosmetically and functionally disfiguring with extensive side effects. An alternate effective therapy for oral cancer is a light based spatially-targeted cytotoxic therapy called photodynamic therapy (PDT). Despite excellent healing of the oral mucosa in PDT, a lack of robust enabling technology for intraoral light delivery has limited its broader implementation. Leveraging advances in 3D printing, we have developed an intraoral light delivery system consisting of modular 3D printed light applicators with pre-calibrated dosimetry and mouth props that can be utilized to perform PDT in conscious subjects without the need of extensive infrastructure or manual positioning of an optical fiber. To evaluate the stability of the light applicators, we utilized an endoscope in lieu of the optical fiber to monitor motion in the fiducial markers. Here we showcase the stability (less than 2 mm deviation in both horizontal and vertical axis) and ergonomics of our applicators in delivering light precisely to the target location in ten healthy volunteers. We also demonstrate in five subjects with T1N0M0 oral lesions that our applicators coupled with a low-cost fiber coupled LED-based light source served as a complete platform for intraoral light delivery achieving complete tumor response with no residual disease at initial histopathology follow up in these patients. Overall, our approach potentiates PDT as a viable therapeutic option for early stage oral lesions that can be delivered in low resource settings.