Use Of Photodynamic Therapy Research Articles

The Latest Look at PDT and Immune Checkpoints.

Photodynamic therapy (PDT) can not only directly eliminate cancer cells, but can also stimulate antitumor immune responses. It also affects the expression of immune checkpoints. The purpose of this review is to collect, analyze, and summarize recent news about PDT and immune checkpoints, along with their inhibitors, and to identify future research directions that may enhance the effectiveness of this approach. A search for research articles published between January 2023 and March 2024 was conducted in PubMed/MEDLINE. Eligibility criteria were as follows: (1) papers describing PDT and immune checkpoints, (2) only original research papers, (3) only papers describing new reports in the field of PDT and immune checkpoints, and (4) both in vitro and in vivo papers. Exclusion criteria included (1) papers written in a language other than Polish or English, (2) review papers, and (3) papers published before January 2023. 24 papers describing new data on PDT and immune checkpoints have been published since January 2023. These included information on the effects of PDT on immune checkpoints, and attempts to associate PDT with ICI and with other molecules to modulate immune checkpoints, improve the immunosuppressive environment of the tumor, and resolve PDT-related problems. They also focused on the development of new nanoparticles that can improve the delivery of photosensitizers and drugs selectively to the tumor. The effect of PDT on the level of immune checkpoints and the associated activity of the immune system has not been fully elucidated further, and reports in this area are divergent, indicating the complexity of the interaction between PDT and the immune system. PDT-based strategies have been shown to have a beneficial effect on the delivery of ICI to the tumor. The utility of PDT in enhancing the induction of the antitumor response by participating in the triggering of immunogenic cell death, the exposure of tumor antigens, and the release of various alarm signals that together promote the activation of dendritic cells and other components of the immune system has also been demonstrated, with the result that PDT can enhance the antitumor immune response induced by ICI therapy. PDT also enables multifaceted regulation of the tumor's immunosuppressive environment, as a result of which ICI therapy has the potential to achieve better antitumor efficacy. The current review has presented evidence of PDT's ability to modulate the level of immune checkpoints and the effectiveness of the association of PDT with ICIs and other molecules in inducing an effective immune response against cancer cells. However, these studies are at an early stage and many more observations need to be made to confirm their efficacy. The new research directions indicated may contribute to the development of further strategies.

Chlorin spiro-Tröger's base as a prospective photosensitizer for photodynamic therapy of cancer

Octahydroxy bis-porphyrin Tröger's base (TB) and octahydroxy porphyrin-chlorin spiro-Tröger's base (spiroTB) derivatives were successfully prepared from their Ni(II) complexes utilizing an optimized demetalation method using H2SO4-TFA followed by demethylation via BBr3. The synthesized TB and spiroTB were then in in vitro experiments for their utility in photodynamic therapy (PDT) of cancer. Compared to temoporfin (mTHPC, Foscan®), the chlorin derivative used in PDT of cancer, TB and spiroTB were localized in lysosomes instead of the endoplasmic reticulum and were found to possess enhanced biocompatibility. Cell culture studies were performed on TRAMP-C2 (prostate cancer), HeLa (cervical cancer), and MRC-5 (non cancerous) cell lines. Both TB and spiroTB displayed negligible dark toxicity but increased production of reactive oxygen species (ROS) when illuminated. In addition, spiroTB displayed significant phototoxicity in TRAMP-C2 cells (IC50, light 0.7 μM after 24 h incubation). Despite the phototoxicity of spiroTB being lower than that of mTHPC (IC50, light 0.02 μM), due to the low dark toxicity (IC50, dark > 100 μM), the therapeutic factor of spiroTB (>150) is six times higher than that of mTHPC (25).

Supramolecular Enhancement of BODIPY Singlet Oxygen Generation Using Bile Salt Micelles

Singlet Oxygen (SO) generation is the core chemical process of many medical and industrial applications. Designing efficient SO-Generating (SOG) agents is a major research focus for its utility in photodynamic therapy, wastewater treatment, material science, and organic synthesis. Photosensitization of ambient oxygen using organic dyes is an efficient approach to generating SO, though their efficiency is often severely hampered due to aggregation-induced deactivation. In this manuscript, we present the utility of bile salt micelle as supramolecular host for promoting SOG in aqueous media for a BODIPY dye, which was otherwise highly inactive. The SOG efficiency in test media was probed by monitoring the oxidation of 1,5-Dihydroxy Naphthalene (DHN) to corresponding quinone (juglone) through spectroscopic and chromatographic methods. In this study, we investigated the use of bile salt micelles as a supramolecular platform for enhancing the SOG efficiency of a BODIPY dye in aqueous media through complexation. Our results show that sodium cholate micelles can solubilize the hydrophobic dye and enhance its ability to generate singlet oxygen, while traditionally used macrocyclic hosts such as Β- and γ-cyclodextrin complexation was found to be far less efficient. Computational modeling revealed that the bile salt micelles form an aggregated complex structure with the dye, leading to improved supramolecular interactions and photophysical properties. This work demonstrates the potential of bile salt micelles as a natural and safe platform for enhancing the activity of nonpolar dyes for PDT applications.

Awareness comportment and attitude of dental practitioners for photodynamic therapy during COVID-19 pandemic: a global survey.

The aim of the study is to evaluate the awareness, comportment and attitude/perception of dentists regarding the use of photodynamic (PD) therapy before and during COVID-19 pandemic around the globe. An online survey was performed by sending out an online questionnaire comprising 21 questions among dental practitioners working in four different countries: Saudi Arabia, Pakistan, Malaysia and United Kingdom. The survey evaluated dental practitioners' level of awareness about the PD therapy, comportment and attitude for its implication and prevalence in daily clinical practice. For statistical significance the Chi-square analysis with Spearman Correlation coefficient was conducted to assess the sub-groups and correlating the factors with the level of awareness of the dental practitioners. A total of 1,219 dental practitioners from four different countries (Saudi Arabia, Pakistan, Malaysia and United Kingdom) responded to the questionnaire. The median age of the respondents was 37, 34, 36 and 39 respectively. The majority of dental practitioners demonstrated to have an acceptable level of awareness regarding PD therapy. Nearly 76%, 74%, 79% and 80% of the individuals from Saudi Arabia, Pakistan, Malaysia and United Kingdom respectively were aware of the role/mechanism of action of the PD therapy. Moreover, in preponderance, practitioners were confident that the effect of PD therapy will not be reduced in patients infected with COVID-19. The majority of dental practitioners were convinced that successful dental treatment due to PD therapy is linked majorly with therapies done in relation to four major dental specialties: prosthodontics, endodontic, restorative dentistry and periodontology. Approximately more than 90% of the dentists were sure that the rate of COVID-19 transmission can be reduced by using PD therapy in oral treatments. The dental practitioners from Saudi Arabia (91%), Pakistan (82%), Malaysia (83%) and United Kingdom (82%) were contented to learn about PD therapy for its use in clinical practice. Nearly more than 95% of the practitioners from the four countries were keen to attend the lectures/hands-on workshops regarding PD therapy to enhance their skills and knowledge. More than 80% of dentists do not refuse the peripheral role of PD therapy with their patients. The respondents from the four countries displayed passable level of awareness regarding basic information of PD therapy and its clinical implication in dental specialty. Nevertheless, there is a need to develop awareness regarding the use of PD therapy among dental practitioners during their undergraduate program. Furthermore, lectures and hands-on workshops should be arranged to train dental practitioners in order to enhance their skills for its solicitation in clinical practice. It is perceived by the dentists in the four countries that the use of PD therapy can effectively reduce COVID-19 rate of transmission.

Spotlight on Photoactivatable Liposomes beyond Drug Delivery: An Enabler of Multitargeting of Molecular Pathways.

The potential of photoactivating certain molecules, photosensitizers (PS), resulting in photochemical processes, has long been realized in the form of photodynamic therapy (PDT) for the management of several cancerous and noncancerous pathologies. With an improved understanding of the photoactivation process and its broader implications, efforts are being made to exploit the various facets of photoactivation, PDT, and the associated phenomenon of photodynamic priming in enhancing treatment outcomes, specifically in cancer therapeutics. The parallel emergence of nanomedicine, specifically liposome-based nanoformulations, and the convergence of the two fields of liposome-based drug delivery and PDT have led to the development of unique hybrid systems, which combine the exciting features of liposomes with adequate complementation through the photoactivation process. While initially liposomes carrying photosensitizers (PSs) were developed for enhancing the pharmacokinetics and the general applicability of PSs, more recently, PS-loaded liposomes, apart from their utility in PDT, have found several applications including enhanced targeting of drugs, coloading multiple therapeutic agents to enhance synergistic effects, imaging, priming, triggering drug release, and facilitating the escape of therapeutic agents from the endolysosomal complex. This review discusses the design strategies, potential, and unique attributes of these hybrid systems, with not only photoactivation as an attribute but also the ability to encapsulate multiple agents for imaging, biomodulation, priming, and therapy referred to as photoactivatable multiagent/inhibitor liposomes (PMILS) and their targeted versions─targeted PMILS (TPMILS). While liposomes have formed their own niche in nanotechnology and nanomedicine with several clinically approved formulations, we try to highlight how using PS-loaded liposomes could address some of the limitations and concerns usually associated with liposomes to overcome them and enhance their preclinical and clinical utility in the future.

RECURRENT RESPIRATORY PAPILLOMATOSIS TREATED WITH RADICAL PHOTODYNAMIC THERAPY

RECURRENT RESPIRATORY PAPILLOMATOSIS TREATED WITH RADICAL PHOTODYNAMIC THERAPY

Bioengineering a Light-Responsive Encapsulin Nanoreactor: A Potential Tool for In Vitro Photodynamic Therapy.

Encapsulins, a prokaryotic class of self-assembling protein nanocompartments, are being re-engineered to serve as "nanoreactors" for the augmentation or creation of key biochemical reactions. However, approaches that allow encapsulin nanoreactors to be functionally activated with spatial and temporal precision are lacking. We report the construction of a light-responsive encapsulin nanoreactor for "on demand" production of reactive oxygen species (ROS). Herein, encapsulins were loaded with the fluorescent flavoprotein mini-singlet oxygen generator (miniSOG), a biological photosensitizer that is activated by blue light to generate ROS, primarily singlet oxygen (1O2). We established that the nanocompartments stably encased miniSOG and in response to blue light were able to mediate the photoconversion of molecular oxygen into ROS. Using an in vitro model of lung cancer, we showed that ROS generated by the nanoreactor triggered photosensitized oxidation reactions which exerted a toxic effect on tumor cells, suggesting utility in photodynamic therapy. This encapsulin nanoreactor thus represents a platform for the light-controlled initiation and/or modulation of ROS-driven processes in biomedicine and biotechnology.

Utility of Photodynamic Therapy in Dentistry: Current Concepts.

The significant growth in scientific and technological advancements within the field of dentistry has resulted in a wide range of novel treatment modalities for dentists to use. Photodynamic therapy (PDT) is an emerging, non-invasive treatment method, involving photosensitizers, light of a specific wavelength and the generation of singlet oxygen and reactive oxygen species (ROS) to eliminate unwanted eukaryotic cells (e.g., malignancies in the oral cavity) or pathogenic microorganisms. The aim of this review article is to summarize the history, general concepts, advantages and disadvantages of PDT and to provide examples for current indications of PDT in various subspecialties of dentistry (oral and maxillofacial surgery, oral medicine, endodontics, preventive dentistry, periodontology and implantology), in addition to presenting some images from our own experiences about the clinical success with PDT.

Rationally Designed Long-Wavelength Absorbing Ru(II) Polypyridyl Complexes as Photosensitizers for Photodynamic Therapy.

The utilization of photodynamic therapy (PDT) for the treatment of various types of cancer has gained increasing attention over the last decades. Despite the clinical success of approved photosensitizers (PSs), their application is sometimes limited due to poor water solubility, aggregation, photodegradation, and slow clearance from the body. To overcome these drawbacks, research efforts are devoted toward the development of metal complexes and especially Ru(II) polypyridine complexes based on their attractive photophysical and biological properties. Despite the recent research developments, the vast majority of complexes utilize blue or UV-A light to obtain a PDT effect, limiting the penetration depth inside tissues and, therefore, the possibility to treat deep-seated or large tumors. To circumvent these drawbacks, we present the first example of a DFT guided search for efficient PDT PSs with a substantial spectral red shift toward the biological spectral window. Thanks to this design, we have unveiled a Ru(II) polypyridine complex that causes phototoxicity in the very low micromolar to nanomolar range at clinically relevant 595 nm, in monolayer cells as well as in 3D multicellular tumor spheroids.

A Paradigm Shift in the Development of Anti-Candida Drugs.

The considerable increase in the incidence of Candida infection in recent times has prompted the use of numerous antifungal agents, which has resulted in the development of resistance towards various antifungal agents. With rising Candida infections, the need for design and development of novel antifungal agents is in great demand. However, new therapeutic approaches are very essential in preventing the mortality rate and improving the patient outcome in those suffering from Candida infections. The present review objective is to describe the burden, types of Candidiasis, mechanism of action of antifungal agents and its resistance and the current novel approaches used to combat candidiasis. We have collected and analyzed 135 different peer-reviewed literature studies pertinent to candidiasis. In this review, we have compiled the major findings from these studies. The review describes the concerns related to candidiasis, its current treatment strategy, resistance mechanisms and imminent ways to tackle the problem. The review explored that natural plant extracts and essential oils could act as sources of newer therapeutic agents, however, the focus was on novel strategies, such as combinational therapy, new antibodies, utilization of photodynamic therapy and adaptive transfer primed immune cells with emphasis on the development of effective vaccination.

Application of the Ethyl Acetate Extract of Cichorium as a Potential Photosensitizer in Photodynamic Therapy Induces Apoptosis and Autophagy in Colorectal Cancer Cell Lines via the Protein Kinase R-Like Endoplasmic Reticulum Kinase Pathway.

The present study aims to evaluate the effect of the ethyl acetate extract of Cichorium (EAEC) as a novel photosensitizer in photodynamic therapy (PDT) of colorectal carcinoma (CRC) HCT116 and SW620 cells. The absorption and fluorescence spectra of EAEC were measured using a UV-vis spectrophotometer and fluorescence spectrophotometer, respectively. EAEC-induced reactive oxygen species (ROS) production in HCT116 and SW620 cells was detected using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) and glutathione/glutathione disulfide (GSH/GSSG). The photo- and dark toxicities of EAEC were estimated using the Cell Counting Kit-8 (CCK-8) assay. Cellular uptake and localization of EAEC were detected by confocal laser fluorescence microscopy. Annexin V-FITC/PI staining, Western blotting and immunofluorescence staining were used to assess apoptosis and autophagy. The antitumor activity of EAEC was confirmed in a xenograft model. Finally, effects on the PERK pathway were verified using qRT-PCR and Western blotting. EAEC displayed absorption and fluorescence emission peaks at 660 nm and 678 nm, respectively. EAEC induced ROS production in CRC cells. Assessment of dark toxicity showed that treatment with EAEC alone induced little cytotoxicity in CRC or normal cells but that EAEC-PDT induced significant photocytotoxicity in CRC cells in a time- and dose-dependent manner. After cellular uptake, EAEC was located in the mitochondria. Treatment with EAEC-PDT reduced xenograft tumor size. Further evaluation suggested that activation of the PERK pathway mediates these effects, as the apoptotic rate and autophagy flux increased markedly after EAEC-PDT. EAEC, a natural photosensitizer extracted from Cichorium, displays potential utility in PDT of CRC by targeting the PERK pathway.

A review and outlook in the treatment of osteosarcoma and other deep tumors with photodynamic therapy: from basic to deep.

Photodynamic therapy, one of the most promising minimally invasive treatments, has received increasing focus in tumor therapy research, which has been widely applied in treating superficial tumors. Three basic factors - photosensitizer, the light source, and oxidative stress - are responsible for tumor cell cytotoxicity. However, due to insufficient luminous flux and peripheral tissue damage, the utilization of photodynamic therapy is facing a huge limitation in deep tumor therapy. Osteosarcoma is the typical deep tumor, which is the most commonly occurring malignancy in children and adolescents. Despite developments in surgery, high risks of the amputation still threatens the health of osteosarcoma patients. In this review, we summarize recent developments in the field of photodynamic therapy and specifically PDT research in OS treatment modalities. In addition, we also provide some novel suggestions, which could potentially be a breakthrough in PDT-induced OS therapies. PDT has the potential to become an effective therapy while the its limitations still present when applied on the treatment of OS or other types of deep tumors. Thus, more researches and studies in the field are required.

Animal models for photodynamic therapy (PDT).

Photodynamic therapy (PDT) employs non-toxic dyes called photosensitizers (PSs), which absorb visible light to give the excited singlet state, followed by the long-lived triplet state that can undergo photochemistry. In the presence of ambient oxygen, reactive oxygen species (ROS), such as singlet oxygen and hydroxyl radicals are formed that are able to kill cancer cells, inactivate microbial pathogens and destroy unwanted tissue. Although there are already several clinically approved PSs for various disease indications, many studies around the world are using animal models to investigate the further utility of PDT. The present review will cover the main groups of animal models that have been described in the literature. Cancer comprises the single biggest group of models including syngeneic mouse/rat tumours that can either be subcutaneous or orthotopic and allow the study of anti-tumour immune response; human tumours that need to be implanted in immunosuppressed hosts; carcinogen-induced tumours; and mice that have been genetically engineered to develop cancer (often by pathways similar to those in patients). Infections are the second biggest class of animal models and the anatomical sites include wounds, burns, oral cavity, ears, eyes, nose etc. Responsible pathogens can include Gram-positive and Gram-negative bacteria, fungi, viruses and parasites. A smaller and diverse group of miscellaneous animal models have been reported that allow PDT to be tested in ophthalmology, atherosclerosis, atrial fibrillation, dermatology and wound healing. Successful studies using animal models of PDT are blazing the trail for tomorrow's clinical approvals.

Tratamiento de carcinoma basocelular con terapia fotodinámica sistémica

ObjectiveTo evaluate therapeutic response, among Venezuelan patients, to photodynamic therapy for basal-cell carcinoma with a chlorine-based photo-sensitizer compound. MethodsPatients included in the study had been diagnosed with single or multiple basalcell carcinomas, based on histopathology for adults, without gender or lesion localization discrimination, and were injected intravenously with the photo-sensitizer, Photolon. After a 3-hour interval, the tumoral zone (or zones) was illuminated with a 662nm wave length diode laser. ResultsTreatment was performed on 43 lesions in 16 patients with favorable response in every case; all clinical evidence of tumor(s) disappeared, which was confirmed by histopathology. Patients presented no complications attributable to treatment and remained under observation with no signs of oncologic disease for 24 months. ConclusionsThe efficiency and utility of photodynamic therapy with Photolon was demonstrated in the treatment of Venezuelan patients with multiple basal cell carcinoma lesions.

The Effect of a Cationic Porphyrin on Pseudomonas aeruginosa Biofilms

Current studies have indicated the utility of photodynamic therapy using porphyrins in the treatment of bacterial infections. Photoactivation of porphyrins results in the production of singlet oxygen ((1)O(2)) that damages biomolecules associated with cells and biofilms, e.g., proteins, polysaccharides, and DNA. The effect of a cationic porphryin on P. aeruginosa PAO1 biofilms was assessed by exposing static biofilms to 5,10,15,20-tetrakis(1-methyl-pyridino)-21H,23H-porphine, tetra-p-tosylate salt (TMP) followed by irradiation. Biofilms were visualized using confocal laser scanning microscopy (CLSM) and cell viability determined using the LIVE/DEAD BacLight viability assay and standard plate counts. At a concentration of 100 μM TMP, there was substantial killing of P. aeruginosa PAO1 wild-type and pqsA mutant biofilms with little disruption of the biofilm matrix or structure. Exposure to 225 μM TMP resulted in almost complete killing as well as the detachment of wild-type PAO1 biofilms. In contrast, pqsA mutant biofilms that contain less extracellular DNA remained intact. Standard plate counts of cells recovered from attached biofilms revealed a 4.1-log(10) and a 3.9-log(10) reduction in viable cells of wild-type PAO1 and pqsA mutant strains, respectively. Our results suggest that the action of photoactivated TMP on P. aeruginosa biofilms is two-fold: direct killing of individual cells within biofilms and detachment of the biofilm from the substratum. There was no evidence of porphyrin toxicity in the absence of light; however, biofilms pretreated with TMP without photoactivation were substantially more sensitive to tobramycin than untreated biofilms.

Characterization of two isomeric beta-d-glucosiduronic acids derived from 1,2-diethyl-3-hydroxypyridin-4-one (CP94) in rat liver homogenate incubates.

1,2-Diethyl-3-hydroxypyridin-4-one (CP94) is an orally active iron chelator with potential for use in photodynamictherapy. This investigation reports the formation and characterization of two isomeric glucuronides of CP94 in rat liver homogenate incubates. To assign the glucuronidation sites in the CP94 molecule, two O-methylated derivatives of CP94 have been synthesized. By comparing the spectral characteristics of the CP94 3-O- and 4-O-methyl derivatives with CP94 and the CP94 glucuronides formed during incubation, evidence was obtained which enabled the assignment of these two isomeric glucuronides to the 3-O-glucuronide and 4-O-glucuronide of CP94. It was found that the 3-O-glucuronide was the dominant CP94 metabolite under in-vitro conditions. In an attempt to understand the potential influence of structural variation on the glucuronidation of CP94 analogues, the 1-and 2-monoethyl derivatives of CP94 were investigated. The 2-monoethyl derivative of CP94 yielded only the 3-O-glucuronide in rat liver homogenate incubate, while no glucuronide was formed from the 1-monoethyl derivative. In addition, no glucuronide from the 3-O-methyl or 4-O-methyl derivatives of CP94 could be detected. The relevance of these findings to the development of new 3-hydroxypyridin-4-one iron chelators is discussed.

Enhanced photodynamic effect of cobalt(iii) dipyridophenazine complex on thyrotropin receptor expressing HEK293 cells

Ternary cobalt(III) complexes [CoL(B)] (1-3) of a trianionic tetradentate phenolate-based ligand (L) and phenanthroline bases (B), viz. 1,10-phenanthroline (phen in 1), dipyridoquinoxaline (dpq in 2) and dipyridophenazine (dppz in 3) are synthesized, characterized from X-ray crystallographic, analytical and spectral techniques, and their utility in photodynamic therapy (PDT) of thyroid diseases caused by TSH receptor dysfunction is probed. The complexes display a visible spectral band within the PDT spectral window at ~690 nm. Photodynamic potential was estimated through DNA cleavage activity of the dpq and dppz complexes in UV-A light of 365 nm and red light of 676 nm. The reactions proceed via the hydroxyl radical pathway. The complexes retain their DNA photocleavage activity in red light under anaerobic conditions, a situation normally prevails in hypoxic tumor core. Investigation into the photocytotoxic potential of these complexes showed that the dppz complex 3 is approximately 4-fold more active in the HEK293 cells expressing human thyrotropin receptor (HEK293-hTSHR) than in the parental cell line and has an insignificant effect on an unrelated human cervical carcinoma cell line (HeLa). Photoexcitation of complex 3 in HEK293-hTSHR cells leads to damage hTSHR as evidenced from the decrease in cAMP formation both in absence and presence of hTSH and decrease in the TSHR immunofluorescence with a concomitant cytoplasmic translocation of the membrane protein, cadherin. The involvement of hTSHR is evidenced from the ability of complex 3 to bind to the extracellular domain of hTSHR (hTSHR-ECD) with a K(d) value of 81 nM and from the photocleavage of hTSHR-ECD.

Studies in Chlorin Chemistry. 3. A Practical Synthesis of C,D-Ring Symmetric Chlorins of Potential Utility in Photodynamic Therapy

[reaction: see text] C,D-ring symmetric chlorins 8 were prepared in 47-85% yield, on scales up to several hundred milligrams, by condensation of appropriately substituted bis-formyldihydrodipyrrins 6 and dipyrromethane bis-carboxylic acids 7 in 5% TFA/CH2Cl2 (25 examples). Target chlorins were chosen to systematically probe the effect of lipophilic and hydrophilic substituents on tissue partitioning and cellular membrane penetration in photodynamic therapy (PDT).

Synthesis of Bacteriochlorins and Their Potential Utility in Photodynamic Therapy (PDT)

The porphyrins and related tetrapyrrole systems are among the most widely studied of all macrocyclic compounds. In fact, in one capacity or another these versatile molecules have influenced nearly all disciplines in chemistry. In recent years, efforts are underway to develop tetrahydroporphyrin-based (bacteriochlorin) compounds with long wavelength absorption in the range of 700-800 nm as photosensitizers for photodynamic therapy (PDT). This review article summarizes the synthetic methodologies that have been developed for the preparation of a variety of bacteriochlorins, either from porphyrins or chlorin systems.

Skin Burn Associated with Pulse Oximetry during Perioperative Photodynamic Therapy

IT was reported in 1967 that tumor destruction could be accomplished with the use of a porphyrin substance when exposed to light 1 . Individually, the light and the chemical may be relatively innocuous, whereas the combination can have significant effects. This principle has been applied to cancer treatment with a technique called photodynamic therapy (PDT). 2,3 PDT is a relatively new cancer treatment modality undergoing clinical trials in the United States. The treatment involves a drug (photosensitizer) that accumulates preferentially in tumor cells and subsequently kills cells on activation by light. We present a case in which the use of conventional perioperative monitoring with a pulse oximeter during PDT resulted in the loss of skin integrity at the site of the pulse oximeter probe.