Pain during topical photodynamic therapy: uncomfortable and unpredictable

Exploring Patient Pain Experiences during and after Conventional Red Light and Simulated Daylight Photodynamic Therapy for Actinic Keratosis: A Qualitative Interview Study

Simulated daylight photodynamic therapy is a relatively new and potentially less painful alternative to conventional red light photodynamic therapy for actinic keratosis. Qualitative research exploring patient experiences of pain and skin reactions during these treatments is scarce. To address this, semi-structured interviews were conducted of 10 patients aged 60-81 years with symmetrically distributed actinic keratoses 4 weeks after split-face treatment with conventional red light photodynamic therapy and simulated daylight photodynamic therapy. The participants were recruited from an ongoing clinical randomized trial. Interviews (median length 35 min) were conducted between June 2022 and January 2023, audio-recorded, transcribed verbatim, and analysed qualitatively using content analysis, as described by Graneheim and Lundman. Participants reported that conventional red light photodynamic therapy was very painful during illumination and transiently painful in the post-treatment period, while simulated daylight photodynamic therapy was almost painless during illumination and led to minor post-treatment pain. Also, skin reactions were more intense and longer-lasting with conventional red light photodynamic therapy than with simulated daylight photodynamic therapy. Most participants expressed a treatment preference for simulated daylight photodynamic therapy but had reservations about its unestablished long-term effectiveness. This study underscores the considerable pain associated with conventional red light photodynamic therapy, and the pivotal importance of shared decision-making when selecting the most appropriate treatment.

On the Possibility of Using 5-Aminolevulinic Acid in the Light-Induced Destruction of Microorganisms

Antimicrobial photodynamic inactivation (aPDI) is a method that specifically kills target cells by combining a photosensitizer and irradiation with light at the appropriate wavelength. The natural amino acid, 5-aminolevulinic acid (5-ALA), is the precursor of endogenous porphyrins in the heme biosynthesis pathway. This review summarizes the recent progress in understanding the biosynthetic pathways and regulatory mechanisms of 5-ALA synthesis in biological hosts. The effectiveness of 5-ALA-aPDI in destroying various groups of pathogens (viruses, fungi, yeasts, parasites) was presented, but greater attention was focused on the antibacterial activity of this technique. Finally, the clinical applications of 5-ALA in therapies using 5-ALA and visible light (treatment of ulcers and disinfection of dental canals) were described.

Modified 5-aminolevulinic acid photodynamic therapy suppresses cutaneous squamous cell carcinoma through blocking Akt/mTOR-mediated autophagic flux

Background: We previously found that modified 5-aminolevulinic acid photodynamic therapy (M-PDT) is painless and effective in cutaneous squamous cell carcinoma (cSCC) treatment, however, the regulatory mechanism of M-PDT in cSCC is still unclear.

Objective: To clarify the effect and relevant regulatory mechanism of M-PDT in cSCC.

Methods: The cSCC apoptosis was examined by flow cytometry, TUNEL staining and Cleaved-caspase-3 immunofluorescence, respectively. The autophagy-related characterization was detected by monodansylcadaverine (MDC) staining, transmission electron microscopy (TEM), GFP-LC3B autophagic vacuoles localization and mRFP-EGFP tandem fluorescence-tagged LC3B construct, respectively. The expression of autophagy-related proteins and Akt/mTOR signaling molecules were examined by Western blot. ROS generation was measured by DCFH-DA probe.

Results: We found that M-PDT induced cSCC apoptosis in a dose-dependent manner, and this result was related to autophagic flux blockage. The phenomenon is confirmed by the results that M-PDT could induce autophagosomes accumulation and upregulate LC3-II and p62 expression. M-PDT elevated co-localization of RFP and GFP tandem-tagged LC3B puncta in cSCC cell, reflecting autophagic flux blockage, and this was confirmed by transmission electron microscopy. Furthermore, we noticed that M-PDT induced accumulated autophagosomes-dependent apoptosis via targeting ROS-mediated Akt/mTOR signaling. Suppression of Akt potentiated M-PDT-induced upregulation of LC3-II and p62 levels, whereas Akt activation and ROS inhibition rendered resistance to these events. In addition, we observed that lysosomal dysfunction was involved in M-PDT-triggered accumulated autophagosomes-dependent cSCC apoptosis.

Conclusion: Our data demonstrates that M-PDT inhibits cSCC through blocking Akt/mTOR-mediated autophagic flux.

Ablative Fractional Laser-assisted Low-irradiance Photodynamic Therapy for Treatment of Actinic Keratoses in Organ Transplant Recipients: A Prospective, Randomized, Intraindividual Controlled Trial

Pain and inferior efficacy are major limiting factors of conventional photodynamic therapy for the field treatment of actinic keratoses in immunosuppressed organ transplant recipients. This prospective randomized controlled study evaluates the efficacy and tolerability of ablative fractional laser system pretreatment combined with low-irradiance photodynamic therapy (18.5 mW/cm2) compared with conventional photodynamic therapy (61.67 mW/cm2) in the treatment of actinic keratoses on the face and scalp in organ transplant recipients, using a red light-emitting diode lamp at a total light dose of 37 J/cm2. Low-irradiance photodynamic therapy combined with Er:YAG pretreatment achieved a significantly superior lesion response rate (mean ± standard deviation 77.3 ± 23.6%) compared with conventional photodynamic therapy (61.8 ± 21.4%; p = 0.025) in intra-individual fields at 3 months without negatively impacting pain (p = 0.777) or cosmetic outcome (p = 0.157).

Nanoparticle-Mediated Photothermal Therapy Limitation in Clinical Applications Regarding Pain Management

The development of new effective cancer treatment methods has attracted much attention, mainly due to the limited efficacy and considerable side effects of currently used cancer treatment methods such as radiation therapy and chemotherapy. Photothermal therapy based on the use of plasmonically resonant metallic nanoparticles has emerged as a promising technique to eradicate cancer cells selectively. In this method, plasmonic nanoparticles are first preferentially uptaken by a tumor and then selectively heated by exposure to laser radiation with a specific plasmonic resonant wavelength, to destroy the tumor whilst minimizing damage to adjacent normal tissue. However, several parameters can limit the effectiveness of photothermal therapy, resulting in insufficient heating and potentially leading to cancer recurrence. One of these parameters is the patient’s pain sensation during the treatment, if this is performed without use of anesthetic. Pain can restrict the level of applicable laser radiation, cause an interruption to the treatment course and, as such, affect its efficacy, as well as leading to a negative patient experience and consequential general population hesitancy to this type of therapy. Since having a comfortable and painless procedure is one of the important treatment goals in the clinic, along with its high effectiveness, and due to the relatively low number of studies devoted to this specific topic, we have compiled this review. Moreover, non-invasive and painless methods for temperature measurement during photothermal therapy (PTT), such as Raman spectroscopy and nanothermometry, will be discussed in the following. Here, we firstly outline the physical phenomena underlying the photothermal therapy, and then discuss studies devoted to photothermal cancer treatment concerning pain management and pathways for improved efficiency of photothermal therapy whilst minimizing pain experienced by the patient.

Modified 5-aminolevulinic acid photodynamic therapy reduces pain and improves therapeutic effects in cutaneous squamous cell carcinoma mouse model

BACKGROUND AND OBJECTIVES

Conventional ALA-PDT (C-PDT) has limited efficacy in cutaneous squamous cell carcinoma (cSCC), and there is obvious pain during treatment, which limits its clinical application. We sought to modify photodynamic therapy into a more painless and effective treatment.

METHODS

We modified C-PDT by reducing the incubation time of the pro-sensitizer and increasing the light dose; we named this method modified ALA-PDT (M-PDT). We compared the pain response and curative effect between C-PDT and M-PDT in cSCC mouse models. Pain-related proteins were examined by western blot analysis and immunohistochemistry. Tumor progression-associated signaling pathways were analyzed by RNA-seq and western blot analysis. Reactive oxygen species (ROS) generation was measured with a ROS test kit and Microplate reader.

RESULTS

M-PDT greatly reduced pain during treatment. Interestingly, when the cSCC tumor volume increased to 150-200 mm³ , M-PDT almost completely eliminated the tumors, while C-PDT did not. The better curative effect of M-PDT might be due to the stronger suppression of the Stat3, Erk1/2, and mTOR signaling pathways. Moreover, flow cytometry demonstrated that M-PDT could recruit CD8⁺ T cells to inhibit cSCC progression. Further investigation determined that the different mechanisms of C-PDT and M-PDT were related to more ROS generation induced by M-PDT.

CONCLUSIONS

Our results suggest that M-PDT, which is more painless and effective than C-PDT, is expected to provide a solution for the treatment of cSCC.

Non-Surgical Treatments for Keratinocyte Carcinomas

Skin cancer is the most common malignancy worldwide, comprising approximately 30% of all human tumors. In recent decades, the incidence of keratinocyte carcinomas, which include basal cell carcinoma and cutaneous squamous cell carcinoma, has been steadily increasing globally (Rogers et al. in JAMA Dermatol 151(10):1081-1086. https://doi.org/10.1001/jamadermatol.2015.1187 , 2015; Nehal and Bichakjian in N Engl J Med 379(4):363-374. https://doi.org/10.1056/nejmra1708701 , 2018). Most tumors are cured with surgical excision; however, some tumors are best treated with non-surgical approaches. Superficial tumors can often be cured with non-surgical methods whereas more advanced stage tumors may not be amenable to surgery. Additionally, surgical treatment may not be available for all populations depending on geographic location and accessibility to care. This article reviews commonly utilized nonsurgical options such as cryotherapy, photodynamic therapy, topical treatments, and radiation as well as systemic treatments including immunotherapies and chemotherapies.

RANDOMIZED CONTROLLED TRIAL FOR EVALUATION OF EFFICACY AND PAIN DURING PHOTODYNAMIC THERAPY FOR ACTINIC KERATOSIS OF FACE AND SCALP COMPARING TWO IRRADIATION PROTOCOLS

BACKGROUND

Pain is a frequent adverse event during photodynamic therapy, which can limit treatment acceptance. This study aimed to evaluate the efficacy and pain during photodynamic therapy with two irradiation protocols in patients with actinic keratosis on the face and scalp.

METHODS

In this intra-patient randomized controlled trial, participants were randomly allocated to receive photodynamic therapy with methyl aminolevulinate and red light on the right or left side with protocol 1 (irradiation device in contact with the skin) and protocol 2 (device 3 cm away from the skin). There was a 15-day interval between the protocols. The primary outcome was the frequency of mean intensity of moderate or severe pain during photodynamic therapy. Secondary outcomes were actinic keratosis clearance rate, protoporphyrin IX consumption, participant preference, skin appearance, and adverse events.

RESULTS

Forty-one participants were included, yielding 47 and 50 randomized sites for protocols 1 and 2. There was no difference in the frequency of moderate and severe pain, with a relative risk of 1.09 (95% CI 0.70-1.70), p>0.05. An actinic keratosis count reduction >60% was observed in both protocols (p<0.01), with no difference between them. There was no difference in protoporphyrin IX consumption. Most treated sites were of good to excellent quality. There was a greater patient preference for protocol 2 (p<0.01).

CONCLUSIONS

The pain intensity was similar between the protocols, and the protocols were equally effective for actinic keratosis clearance, protoporphyrin IX consumption, and improvement in the quality of the treated areas. Both protocols can be considered safe.

Reducing non-melanoma skin cancer risk in renal transplant recipients

With an increasing number of renal transplant recipients (RTRs) and improving patient survival, a higher incidence of non-melanoma skin cancer (NMSC) has been observed. NMSC in RTRs are often more numerous and biologically more aggressive than the general population, thus contributing towards an increase in morbidity and to a lesser degree, mortality. The resultant cumulative health and financial burden is a recognized concern. Proposed strategies in mitigating risks of developing NMSC and early therapeutic options thereof include tailored modification of immunosuppressants in conjunction with sun protection in all transplant patients. This review highlights the clinical and financial burden of transplant-associated skin cancers, carcinogenic mechanisms in association with immunosuppression, importance of skin cancer awareness campaign and integrated transplant skin clinic, and the potential role of chemoprotective agents. A scheme is proposed for primary and secondary prevention of NMSC based on the available evidence.

Painless Photodynamic Therapy Triggers Innate and Adaptive Immune Responses in a Murine Model of UV-induced Squamous Skin Pre-cancer

Painless photodynamic therapy (p-PDT), which involves application of photosensitizer and immediate exposure to light to treat actinic keratosis (AK) in patients, causes negligible pain on the day of treatment but leads to delayed inflammation and effective lesion clearance (Kaw et al., J Am Acad Dermatol 2020). To better understand how p-PDT works, hairless mice with UV-induced AK were treated with p-PDT and monitored for 2 weeks. Lesion clearance after p-PDT was similar to clearance after conventional PDT (c-PDT). However, lesion biopsies showed minimal cell death and less production of reactive oxygen species (ROS) in p-PDT treated than in c-PDT-treated lesions. Interestingly, p-PDT triggered vigorous recruitment of immune cells associated with innate immunity. Neutrophils (Ly6G+) and macrophages (F4/80+) appeared at 4 h and peaked at 24 h after p-PDT. Damage-associated molecular patterns (DAMPs), including calreticulin, HMGB1, and HSP70, were expressed at maximum levels around 24 h post-p-PDT. Total T cells (CD3+) were increased at 24 h, whereas large increases in cytotoxic (CD8+) and regulatory (Foxp3+) T cells were observed at 1 and 2 weeks post-p-PDT. In summary, the ability of p-PDT to eliminate AK lesions, despite very little overt cellular damage, appears to involve stimulation of a local immune response.

Comparative study of imiquimod 3.75% vs. photodynamic therapy for actinic keratosis of the scalp

BACKGROUND/PURPOSE

To assess efficacy, tolerability, adverse effects, recurrence, and aesthetic results of imiquimod 3.75% vs. photodynamic therapy with 5-aminolaevulinic acid (MAL-PDT) for actinic keratosis (AK).

METHODS

A small randomized, intraindividual right-left pilot study for AK treatment of multiple scalp lesions was performed. Patients were treated with imiquimod and subsequently MAL-PDT (on opposite sides of the scalp) 14 days apart. Study end points were evaluated with clinical and dermoscopic examinations at 1, 3, 6, and 12 months.

RESULTS

Nine male bald patients were enrolled. Imiquimod achieved a slightly higher overall clearance rate than MAP-PDT (68.1% vs 56.5%). According to AK degree of severity, clearance rates were greater for degree I and III with imiquimod (68.8%, 64.5% and 75% with imiquimod vs. 48%, 69.8%, and 66.7% for MAL-PDT, respectively). At 12 months, a slightly higher total recurrence rate was noted for imiquimod compared with MAL-PDT (9.9% vs. 8.6%); new lesions were 2 degree I for imiquimod and 4 degree I for MAL-PDT. For both treatments, pain was moderate/strong (even if MAL-PDT seems to be less tolerable) adverse effects are common and transient; aesthetic results excellent.

CONCLUSION

Both imiquimod and MAL-PDT were effective in the reduction in the number of AK. In the long-term, both present a good effectiveness maintained over time with excellent aesthetic results. A combination or sequential therapy could optimize the management of the cancerization field.

A New Light-Emitting, Fabric-Based Device for Photodynamic Therapy of Actinic Keratosis: Protocol for a Randomized, Controlled, Multicenter, Intra-Individual, Phase II Noninferiority Study (the Phosistos Study)

BACKGROUND

Actinic keratosis (AK) is a common early in situ skin carcinoma caused by long-term sun exposure and usually develops on sun-exposed skin areas. Left untreated, AK may progress to squamous cell carcinoma. To prevent such risk, most clinicians routinely treat AK. Therapy options for AK include cryotherapy, topical treatments, curettage, excision surgery, and photodynamic therapy (PDT).

OBJECTIVE

The aim of this study is to assess the noninferiority, in terms of efficacy at 3 months, of a PDT protocol involving a new light-emitting device (PDT using the Phosistos protocol [P-PDT]) compared with the conventional protocol (PDT using the conventional protocol [C-PDT]) in the treatment of AK.

METHODS

In this randomized, controlled, multicenter, intra-individual, phase II noninferiority clinical study, subjects with AK of the forehead and scalp are treated with P-PDT on one area and with C-PDT on the contralateral area. In both areas, lesions are prepared and methyl aminolevulinate (MAL) is applied. Thirty minutes after MAL application, the P-PDT area is exposed to red light at low irradiance (1.3 mW/cm²) for 2.5 hours so that a light dose of 12 J/cm² is achieved. In the control area (C-PDT area), a 37 J/cm² red light irradiation is performed 3 hours after MAL application. Recurrent AK at 3 months is retreated. The primary end point is the lesion complete response rate at 3 months. Secondary end points include pain scores at 1 day, local tolerance at 7 days, lesion complete response rate at 6 months, cosmetic outcome at 3 and 6 months, and patient-reported quality of life and satisfaction throughout the study. A total of 45 patients needs to be recruited.

RESULTS

Clinical investigations are complete: 46 patients were treated with P-PDT on one area (n=285 AK) and with C-PDT on the contralateral area (n=285 AK). Data analysis is ongoing, and statistical results will be available in the first half of 2019.

CONCLUSIONS

In case of noninferiority in efficacy and superiority in tolerability of P-PDT compared with C-PDT, P-PDT could become the treatment of choice for AK.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03076892; https://clinicaltrials.gov/ct2/show/NCT03076892 (Archived by WebCite at http://www.webcitation.org/779qqVKek).

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/12990.

Field Cancerization Therapies for Management of Actinic Keratosis: A Narrative Review

Actinic keratoses (AKs) are atypical, precancerous proliferations of keratinocytes that develop because of chronic exposure to ultraviolet (UV) radiation. Treatment of AK can be lesion-directed or field-directed. Field cancerization theory postulates that the skin surrounding AK is also at increased risk for possible malignant transformation since it has been exposed to the same chronic UV light. Field-directed therapies thus have the potential to address subclinical damage, reduce AK recurrence rates, and potentially reduce the risk of squamous cell carcinoma (SCC) development. Published clinical studies have found lesion clearance rates ranging from 81 to 91% for photodynamic therapy (PDT) with either aminolevulinic acid (ALA) or methylaminolevulinate (MAL). Clinical studies have also been published on various topical treatments. Complete clinical clearance (CCC) was significantly higher in patients treated with a combination of 5-fluorouracil and salicylic acid (5-FU-SA) than in the vehicle group across multiple studies, and CCC ranged between 46 and 48% following treatment with imiquimod. Additionally, treatment with diclofenac sodium (DFS) found reduction in lesion sizes to range from 67 to 75%. Reported results have been similar for another non-steroidal anti-inflammatory drug (NSAID), piroxicam, which has more cyclooxygenase (COX)-1 activity than DFS. Active treatments with ingenol mebutate were also significantly more effective than vehicle at clearing AK lesions. All treatments resulted in mild, localized skin reactions. PDT using conventional light sources was associated with increased severity of pain and/or discomfort, while PDT using daylight as the light source was associated with less pain and occasionally no pain at all. Though no widely accepted algorithm for the treatment of AKs exists, field-directed therapy can be particularly useful for treating photo-exposed areas containing multiple AKs. Additional research with more direct comparisons between these field-directed therapies will help clinicians determine the best therapeutic approach. Here, we provide a balanced and comprehensive narrative review of the literature, considering both light-based and topical therapies with a focus on their field-therapy aspects, and propose a therapeutic algorithm for selecting an appropriate treatment in the clinical setting.

The influence of different illumination parameters on protoporphyrin IX induced cell death in squamous cell carcinoma cells

BACKGROUND

Topical photodynamic therapy (PDT) is a highly effective therapy especially for extended cancerized fields of the skin. Whenever extended fields are treated pain management is advisable. Light source mediated pain management can be performed by reducing fluence rates, as long as this does not compromise efficacy.

METHODS

Two squamous cell carcinoma cell lines (A431 and SCC-13) were subjected to in vitro PDT using two different ALA concentrations and synthesis intervals and protoporphyrin IX (PpIX) synthesis was assessed. Two total light doses (6 J/cm² and 37 J/cm²) were applied at three different fluence rates and cell viability was measured using the MTS-test.

RESULTS

Both cell lines synthetized PpIX at different kinetics. A431 cells produced a maximum 28.6 nmol/l PpIX, while SCC-13 reached only a production of 8.7 nmol/l. Illumination reduced cell viability depending on PpIX content and light dose. When a lower light dose (6 J/cm²) was applied, only the combination with the highest PpIX content was effective in A431 cells and no effect could be detected in SCC-13 cells. With a light dose of 37 J/cm², lower PpIX amounts became effective in A431 and cell death could be induced in SCC-13 cells. Light fluence rate had no differential effect in this setup.

CONCLUSIONS

In both, A431 and SCC-13 cells, total light dose is a key factor for photodynamic efficacy. Additionally, our results hint towards a threshold concentration of PpIX upon which a drastic loss of viability occurs. Light fluence rate in the analyzed range is not a limiting factor of photodynamic cytotoxicity. This may allow for the clinical implementation of low fluence rate protocols for pain management without compromising efficacy.

Early and Late Onset Side Effects of Photodynamic Therapy

Photodynamic Therapy (PDT) is a non-invasive treatment successfully used for neoplastic, inflammatory and infectious skin diseases. One of its strengths is represented by the high safety profile, even in elderly and/or immuno-depressed subjects. PDT, however, may induce early and late onset side effects. Erythema, pain, burns, edema, itching, desquamation, and pustular formation, often in association with each other, are frequently observed in course of exposure to the light source and in the hours/days immediately after the therapy. In particular, pain is a clinically relevant short-term complication that also reduces long-term patient satisfaction. Rare complications are urticaria, contact dermatitis at the site of application of the photosensitizer, and erosive pustular dermatosis. Debated is the relationship between PDT and carcinogenesis: the eruptive appearance of squamous cell carcinoma (SCC) in previously treated areas has been correlated to a condition of local and/or systemic immunosuppression or to the selection of PDT-resistant SCC. Here we review the literature, with particular emphasis to the pathogenic hypotheses underlying these observations.

Photodynamic therapy--aspects of pain management

Topical photodynamic therapy (PDT) is a highly effective and safe treatment method for actinic keratoses with an excellent cosmetic outcome and is commonly used for the therapy of large areas of photodamaged skin with multiple clinically manifest and subclinical lesions. However, the major drawback of photodynamic therapy is the pain experienced during the treatment that can be intense and sometimes even intolerable for patients, requiring interruption or termination of the process. Several strategies for controlling pain during photodynamic therapy have been studied but few effective methods are currently available. Therefore, this review puts the spotlight on predictors on pain intensity and aspects of pain management during photodynamic therapy.

A prospective study of pain control by a 2-step irradiance schedule during topical photodynamic therapy of nonmelanoma skin cancer

BACKGROUND

Topical photodynamic therapy (PDT) for selected nonmelanoma skin cancer using 5-aminolevulinic acid (ALA) or methyl aminolevulinate (MAL) has yielded high long-term complete response rates with very good cosmesis. Pain during light activation of the photosensitizer can be a serious adverse event. A 2-step irradiance protocol has previously been shown to minimize ALA-PDT pain.

OBJECTIVE

To determine the irradiance-dependent pain threshold for MAL-PDT, to adapt the 2-step protocol to a light-emitting diode (LED) light source, and assess clinical response.

METHODS

In this prospective study, 25 superficial basal cell carcinoma (sBCC) received an initial irradiance by laser at 40 or 50 mW/cm², or LED at 35 mW/cm² followed by an irradiance at 70 mW/cm² for a total of 75 J/cm². Pain levels were recorded for both irradiance steps. Efficacy was assessed at 6, 12, or 24 months.

RESULTS

Pain was mild in the 40/70 mW/cm² laser cohort. Three instances of irradiance-limiting pain occurred at 50/70 mW/cm². Pain was minimal in the 35/70 mW/cm² LED cohort. Clinical response rates were 80% in the 50/70 mW/cm² laser cohort and 90% in the 35/70 mW/cm² LED cohort.

CONCLUSION

Topical PDT can be effectively delivered to sBCC with minimal treatment-related pain by a 2-step irradiance protocol.

Non-melanoma skin cancers: photodynamic therapy, cryotherapy, 5-fluorouracil, imiquimod, diclofenac, or what? Facts and controversies

Surgical modalities-excision, Mohs micrographic surgery, and electrodesiccation with curettage-are the preferred treatments for nonmelanoma skin cancer (NMSC). When used within guidelines, they have cure rates greater than 90%. Despite this, many other treatments have been studied and utilized for NMSC. We present a comprehensive review of the literature on these topical treatments. Photodynamic therapy (PDT) is administered under numerous and significantly varied regimens, and there are a wide range of cure rates reported. Even with aggressive regimens, PDT is not as effective as surgery is, and it is not a first-line therapy for NMSC. The cryotherapy regimen aggressive enough to adequately treat NMSC carries adverse effects and cosmetic outcomes poor enough to negate its usefulness. Topical 5-fluorouracil and imiquimod are efficacious and safe for the treatment of superficial basal cell carcinoma (BCC) but not other BCC subtypes or squamous cell carcinoma. They are self-administered twice daily for several weeks; therefore, patient and tumor selection are vital to ensuring adherence. There are currently insufficient data to support the use of topical diclofenac and ingenol mebutate for NMSC.

Use of photodynamic therapy for treatment of actinic keratoses in organ transplant recipients

Solid organ transplant recipients are predisposed to actinic keratoses (AK) and nonmelanoma skin cancers, owing to the lifelong immunosuppression required. Today, increasing numbers of organ transplants are being performed and organ transplant recipients (OTRs) are surviving much longer. Photodynamic therapy (PDT) is proving a highly effective treatment modality for AK amongst this susceptible group of patients. Following an overview of the pathogenesis of AK amongst OTRs, the authors review current safety and efficacy data and how this relates to the role of PDT for the treatment of AK in OTRs.

European guidelines for topical photodynamic therapy part 1: treatment delivery and current indications - actinic keratoses, Bowen's disease, basal cell carcinoma

Topical photodynamic therapy (PDT) is a widely used non-invasive treatment for certain non-melanoma skin cancers, permitting treatment of large and multiple lesions with excellent cosmesis. High efficacy is demonstrated for PDT using standardized protocols in non-hyperkeratotic actinic keratoses, Bowen's disease, superficial basal cell carcinomas (BCC) and in certain thin nodular BCC, with superiority of cosmetic outcome over conventional therapies. Recurrence rates following PDT are typically equivalent to existing therapies, although higher than surgery for nodular BCC. PDT is not recommended for invasive squamous cell carcinoma. Treatment is generally well tolerated, but tingling discomfort or pain is common during PDT. New studies identify patients most likely to experience discomfort and permit earlier adoption of pain-minimization strategies. Reduced discomfort has been observed with novel protocols including shorter photosensitizer application times and in daylight PDT for actinic keratoses.

Pain in photodynamic therapy: mechanism of action and management strategies

Photodynamic therapy involves administration of a photosensitizing drug and its subsequent activation by irradiation with a light source at wavelengths matching the absorption spectrum of the photosensitizer. In many countries around the world, topical photodynamic therapy has been approved for treatment of cutaneous oncologic conditions such as actinic keratosis, Bowen's disease, and superficial basal cell carcinoma. Multicenter, randomized, controlled studies have confirmed its efficacy and superior cosmetic outcomes compared to conventional therapies. Nevertheless, this therapeutic method presents some adverse effects, such as erythema, edema, pigmentation, pustules, and pain. There is no doubt that pain is the most severe of the adverse effects, being sometimes responsible for definitive treatment interruption. The pain mechanism has not yet been fully understood, which makes complete pain control a challenge to be conquered. In spite of that, this literature review presents some useful pain management strategies as well as the most important pain-related factors in photodynamic therapy.

Non-ablative fractional resurfacing in combination with topical tretinoin cream as a field treatment modality for multiple actinic keratosis: a pilot study and a review of other field treatment modalities

BACKGROUND

Actinic keratoses (AK) are premalignant lesions occurring mainly in sun-damaged skin. Current topical treatment options for AK and photo-damaged skin such as liquid nitrogen and electrosurgery are not suitable for field treatment. Otherwise, therapies suitable for field treatment bring along considerable patient discomfort. Non-ablative fractional resurfacing has emerged as a logical treatment option especially for field treatment of AK.

OBJECTIVES

To evaluate the clinical efficacy of fractional laser therapy for clearing AK and improving skin quality. To compare patient friendliness of the "fractional" therapy with those reported for other field treatment modalities.

MATERIALS & METHODS

Ten patients with Fitzpatrick skin type I to III with multiple AK and extensive sun-damaged skin, received 5-10 sessions with a 4-week interval using a 1550 nm Erbium-Glass Fractionated laser (Sellas, Korea). Four weeks and 24 weeks after the last treatment the clinical results were evaluated by an independent physician.

RESULTS

The mean degree of improvement, in terms of reduction in the number of AK and improvement of skin texture, was 54% on a 4 point PGA scale, and persisted for approximately 6 months. The biggest advantage of fractional laser treatment, besides the eradication of AK and a clear rejuvenation effect, is the absence of "downtime".

CONCLUSION

Fractional non-ablative resurfacing induces significant reduction in the number of AK and improves the skin quality. Also all patients preferred fractional laser therapy above other AK treatment modalities.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

Photodynamic therapy in the treatment of extensive Bowen's disease

BACKGROUND

Surgical excision is the preferred method of eradicating Bowen´s disease (BD). Photodynamic therapy (PDT) has been successfully used for treatment of actinic keratosis, basal cell carcinoma, and BD.

OBJECTIVE

Our aim was to evaluate the efficacy and tolerability of PDT for treatment of extensive BD.

METHOD

Eighteen patients with 23 biopsy-proven BD lesions were treated with PDT. We defined as extensive those lesions large than 3 cm. Methyl aminolevulinate cream was applied for 3 h before illumination with an light emitting diode light source at a wavelength of 630 nm (energy density of 37 J/cm²). Treatment was repeated 1 week later.

RESULTS

After 12 weeks of treatment, 22 of 23 BD lesions (90%) showed complete clinical response. Only three lesions recurred after a follow-up period of 12 months. Cosmetic outcome at 12 months was good or excellent in 94% of patients.

CONCLUSION

Methyl aminolevulinate PDT is an effective treatment option for extensive BD with excellent cosmesis.