A new photodynamic therapy protocol for nodular basal cell carcinoma treatment: Effectiveness and long-term follow-up

BACKGROUND

Photodynamic therapy (PDT) has been reported as an excellent option for the treatment of small nodular basal cell carcinomas (nBCC). The standard protocol consists of two sessions, one week apart. Sometimes, returning to the hospital after one week can be impractical for elderly patients, due to comorbidities and mobility issues. Therefore, a new technique performed in one day could be superior for those patients.

OBJECTIVE

Evaluate the effectiveness of a PDT Single-visit protocol comparing to the standard protocol, as well as pain and long-term recurrence-free follow-up for nBCC.

METHODS

A total of 120 nBCC were treated through a Standard PDT protocol(two sessions, one week apart), and 120 nBCC were treated through a Single-visit PDT(two sessions in one day). A 30-day-after biopsy was performed in order to evaluate the results after the treatment. The lesions that had successful treatment were clinically and dermoscopically evaluated every 6 months up to 60 months. The pain score was compared between the groups(assessed every 3 min during PDT).

RESULTS

A complete response at 30-days-after PDT biopsy was observed in 85% of Standard PDT and in 93.3% of Single-visit PDT. Regarding the pain during the illumination, less pain was observed during the second session of the Single-visit PDT. The recurrence-free follow up showed, after 60 months, an 69.0% cumulative probability of recurrence-free for Standard PDT and 80.6% for Single-visit PDT.

CONCLUSIONS

The suggested Single-visit PDT protocol resulted in better outcomes at 30-day-after PDT biopsy and in lower recurrence rates than the Standard PDT protocol. A more comfortable and more efficient treatment was offered for the patients, with lower pain.

Optical clearing agent increases effectiveness of photodynamic therapy in a mouse model of cutaneous melanoma: an analysis by Raman microspectroscopy

Melanoma is the most aggressive type of skin cancer and a relevant health problem due to its poor treatment response with high morbidity and mortality rates. This study, aimed to investigate the tissue changes of an improved photodynamic therapy (PDT) response when combined with optical clearing agent (OCA) in the treatment of cutaneous melanoma in mice. Photodithazine (PDZ) was administered intraperitoneally and a solution of OCA was topically applied before PDT irradiation. Due to a resultant refractive index matching, OCA-treated tumors are more optically homogenous, improving the PDT response. Raman analysis revealed, when combined with OCA, the PDT response was more homogenous down to 725 µm-depth in thickness.

Temperature effect on the PpIX production during the use of topical precursors

Decreasing incubation time, as well as enhanced PpIX production, are present challenges for topical photodynamic therapy (PDT). There are reports concerning the existence of a strong relationship between site temperature and porphyrin synthesis in biological tissue, that suggest temperature increase in the tissue can improve the formation of PpIX. The main objective of this study is to determine whether the temperature change of the tissue favors the production of PpIX. Creams containing aminolevulinic acid (ALA) and methyl aminolevulinate (MAL) were topically administered for 30 min on healthy skin of rats' back and the formation of PpIX was evaluated for 180 min. The animals were divided into 5 groups: cooling tissue to 20 °C or heating tissue to 40 °C (either before or after incubation of the cream) and control group (unchanged temperature). The tissue temperature was evaluated by thermography. The influence of temperature was evaluated both concerning cream penetration and the production of PpIX. It was found that both ALA and MAL led to an increase of about 20% PpIX production when the tissue was warmed before incubation of the cream, suggesting that the penetration improved. When the thermal change was promoted after incubation of the cream, the production of PpIX decreased both by heating and cooling, probably related to enzyme modification. The results found in this study suggest that the increase of tissue temperature before the cream incubation can improve the clinical protocols of topical PDT using ALA or MAL, improving the efficiency of the procedure by increasing the production of PpIX and allowing the decrease of the incubation period.

Photodynamic therapy dosimetry using multiexcitation multiemission wavelength: toward real-time prediction of treatment outcome

Evaluating the optical properties of biological tissues is needed to achieve accurate dosimetry during photodynamic therapy (PDT). Currently, accurate assessment of the photosensitizer (PS) concentration by fluorescence measurements during PDT is typically hindered by the lack of information about tissue optical properties. In the present work, a hand-held fiber-optic probe instrument monitoring fluorescence and reflectance is used for assessing blood volume, reduced scattering coefficient, and PS concentration facilitating accurate dosimetry for PDT. System validation was carried out on tissue phantoms using nonlinear least squares support machine regression analysis. It showed a high correlation coefficient (>0.99) in the prediction of the PS concentration upon a large variety of phantom optical properties. In vivo measurements were conducted in a PDT chlorine e6 dose escalating trial involving 36 male Swiss mice with Ehrlich solid tumors in which fluences of 5, 15, and 40  J cm  -  2 were delivered at two fluence rates (100 and 40  mW cm  -  2). Remarkably, quantitative measurement of fluorophore concentration was achieved in the in vivo experiment. Diffuse reflectance spectroscopy (DRS) system was also used to independently measure the physiological properties of the target tissues for result comparisons. Then, blood volume and scattering coefficient measured by the fiber-optic probe system were compared with the corresponding result measured by DRS and showed agreement. Additionally, tumor hemoglobin oxygen saturation was measured using the DRS system. Overall, the system is capable of assessing the implicit photodynamic dose to predict the PDT outcome.

Overall Results for a National Program of Photodynamic Therapy for Basal Cell Carcinoma: A Multicenter Clinical Study to Bring New Techniques to Social Health Care

Along the past years, a national program to implement photodynamic therapy (PDT) for nonmelanoma skin cancer (NMSC) was performed over the Brazilian territory. Using a strategy involving companies, national bank, and medical partners, equipment, medication, and protocols were tested in a multicenter study. With results collected over 6 years, we could reach a great deal of advances concerning the use of PDT for skin cancer. We present the overall reached results of the program and discuss several aspects about it, including public politics of treatment. A discussion about advantages of this technique within conditions of health care is placed, comparing PDT with surgery, including an analysis about the implementation of PDT in countries in development as Brazil, considering not only technical but social aspects, as the distribution of medical doctor in the Brazilian territory. The program resulted in a huge dissemination of PDT in Brazil and many countries in Latin America, in a partnership among public politics, universities, companies, and hospitals and clinics and in the insertion of national technologies as option to treat NMSC. Consequence of the program is mainly the continuation of the use of PDT in Brazil and many countries in Latin America.

Energy analysis of PDT using thermography during the treatment of basal cell carcinoma

The changes in tissue temperature of basal cell carcinoma lesions were investigated during photodynamic therapy in order to better understand the effects and mechanisms of PDT in tissue. In this study, the monitoring of 40 lesions of basal cell carcinoma was performed during photodynamic therapy. The lesion region becomes thermally evident throughout the procedure, and there is an improved contrast of the lesion edges after the end of the irradiation. The comparison between thermal and fluorescence images showed a correlation between the PpIX evidenced through widefield fluorescence and the temperature gradient of the thermal images after the procedure, indicating that thermography is a potential diagnostic tool to evaluate the selective response of PDT. A model was created to calculate the amount of light energy converted to heat, tissue damage, and other energy transfer processes involved in the PDT. Using this model, it was shown that most of the energy conversion was in photodynamic action (48.7% and 48.3%, in first and second session, respectively), followed by the energy ratio attributable to blood perfusion (37.2%). This is evidence that photodynamic therapy does not generate a significant thermal component, an important aspect of the study of its mechanisms.

Antimicrobial action of photodynamic therapy in root canals using LED curing light, curcumin and carbopol gel

AIM

To evaluate the capacity of carbopol gel to maintain the intensity of a LED curing light (blueLED) along the length of prepared root canals in bovine teeth, and to assess the antimicrobial capacity of curcumin photoactivated by a LED curing light in the presence of carbopol gel.

METHODOLOGY

Experiment 1: Eight straight roots of bovine incisors were standardized to a length of 15 mm, and the root canals instrumented up to a size 120 K-file. The LED curing light was irradiated inside the root canals using an aluminium collimator (1.5 mm in diameter) placed at the orifice (n = 8). Initially, the irradiation was performed in empty root canals and then repeated with the root canals filled with carbopol gel. Simple standardized photographs of the roots were taken with a digital camera in the mesial perspective during the irradiation procedure and the images analysed in OriginLab software to verify the light intensity along the length of the root. Experiment 2: Twenty dentine blocks were obtained from the cervical third of bovine incisors using a trephine bur. Biofilms were induced for 21 days on the blocks using Enterococcus faecalis (ATCC 4083) at 10⁹ cells mL^-1 . The blocks were treated according to the groups (n = 5): positive control; standard PDT (methylene blue + diode Laser); curcumin; LED curing light; and curcumin + LED curing light. After the treatment, the samples were dyed with Live/Dead BacLight Bacterial Viability solution and fluorescence images were obtained by Confocal Scanning Laser Microscopy (CSLM). Experiment 3: Thirty-two roots of bovine incisors were prepared as described in experiment 1. Their dentinal tubules were contaminated and the root canals treated according to the groups (n = 8): positive control; standard PDT; curcumin + LED curing light; curcumin + carbopol gel + LED curing light. The specimens were sectioned longitudinally and the split roots were treated with the Live/Dead dye to obtain fluorescence images by CSLM. All images were processed using BioImageL software to measure the percentage of viable bacteria and the data analysed statistically using the nonparametric Kruskal-Wallis test (α < 0.05).

RESULTS

In Experiment 1, carbopol gel did not improve the intensity of LED light transmission along the root canal. In Experiment 2, a significant decrease (P < 0.05) in bacterial viability occurred in the following order: positive control < only LED curing light < only curcumin < curcumin + LED curing light = standard PDT; and in Experiment 3 positive control = curcumin + LED curing light ≤ curcumin + gel + LED curing light ≤ standard PDT.

CONCLUSION

Similar disinfection effectiveness was obtained using curcumin + LED curing light and methylene blue + 660 nm LASER (standard PDT). The use of carbopol gel did not favour a greater transmission of LED light along the root canal and also resulted in less bacterial killing when used in endodontic PDT.

Vascular Effects of Photodynamic Therapy with Curcumin in a Chorioallantoic Membrane Model

Photodynamic Therapy (PDT) is a treatment that requires light, a photosensitizing agent, and molecular oxygen. The photosensitizer is activated by light and it interacts with the oxygen that is present in the cellular microenvironment. The molecular oxygen is transformed into singlet oxygen, which is highly reactive and responsible for the cell death. Therefore, PS is an important element for the therapy happens, including its concentration. Curcumin is a natural photosensitizer and it has demonstrated its anti-inflammatory and anti-oxidant effects that inhibit several signal transduction pathways. PDT vascular effects of curcumin at concentrations varying from 0.1 to 10 mM/cm² and topical administration were investigated in a chick Chorioallantoic Membrane (CAM) model. The irradiation was performed at 450 nm, irradiance of 50 mW/cm² during 10 min, delivering a total fluence of 30 J/cm². The vascular effect was followed after the application of curcumin, with images being obtained each 30 min in the first 3 h, 12 h, and 24 h. Those images were qualitatively and quantitatively analyzed with a MatLAB®. Curcumin was expected to exhibit a vascular effect due to its angio-inhibitory effect. Using curcumin as photosensitizer, PDT induced a higher and faster vascular effect when compared to the use of this compound alone.

Time-resolved fluorescence lifetime for cutaneous melanoma detection

Melanoma is the most aggressive skin cancer type. It is characterized by pigmented lesions with high tissue invasion and metastatic potential. The early detection of melanoma is extremely important to improve patient prognosis and survival rate, since it can progress to the deadly metastatic stage. Presently, the melanoma diagnosis is based on the clinical analysis of the macroscopic lesion characteristics such as shape, color, borders following the ABCD rules. The aim of this study is to evaluate the time-resolved fluorescence lifetime of NADH and FAD molecules to detect cutaneous melanoma in an experimental in vivo model. Forty-two lesions were analyzed and the data was classified using linear discriminant analysis, a sensitivity of 99.4%, specificity of 97.4% and accuracy of 98.4% were achieved. These results show the potential of this fluorescence spectroscopy for melanoma detection.

Relationship between the chemical and morphological characteristics of human dentin after Er:YAG laser irradiation

The effects of laser etching on dentin are studied by microenergy-dispersive x-ray fluorescence spectrometry (μ-EDXRF) and scanning electron microscopy (SEM) to establish the correlation of data obtained. Fifteen human third molars are prepared, baseline μ-EDXRF mappings are performed, and ten specimens are selected. Each specimen received four treatments: acid etching (control-CG) or erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation (I-100 mJ, II-160 mJ, and III-220 mJ), and maps are done again. The Ca and P content are significantly reduced after acid etching (p<0.0001) and increased after laser irradiation with 220 mJ (Ca: p<0.0153 and P: p=0.0005). The Ca/P ratio increased and decreased after CG (p=0.0052) and GI (p=0.0003) treatments, respectively. CG treatment resulted in lower inorganic content (GI: p<0.05, GII: p<0.01, and GIII: p<0.01) and higher Ca/P ratios than laser etching (GI: p<0.001, GII: p<0.01, and GIII: p<0.01). The SEM photomicrographies revealed open (CG) and partially open dentin tubules (GI, GII, and GIII). μ-EDXRF mappings illustrated that acid etching created homogeneous distribution of inorganic content over dentin. Er:YAG laser etching (220 mJ) produced irregular elemental distribution and changed the stoichiometric proportions of hydroxyapatite, as showed by an increase of mineral content. Decreases and increases of mineral content in the μ-EDXRF images are correlated to holes and mounds, respectively, as found in SEM images.

Apical sealing quality of in vitro apicectomy procedures after using both Er:YAG and Nd:YAG

The aim of this study was to evaluate the apical sealing of dentinal tubules after root-end surface cutting by using Er:YAG and Nd:YAG lasers. After root-canal instrumentation and filling, apices of 50 extracted maxillary canine human teeth were resected by Er:YAG with 400 mJ, 10 Hz, for 30 sec. The samples were randomly assigned to five groups (n = 10): (GI) treated without root-end cavity, but with Nd:YAG (1.0 W, 10 Hz, 20 sec) for dentinal tubules sealing; (GII) treated with root-end cavity without the use of Nd:YAG; (GIII) treated with root-end cavity and Nd:YAG application; (GIV) treated with root-end cavity made by Er:YAG with no focus and without Nd:YAG application; and (GV) treated without root-end cavity and without Nd:YAG application. The root-end cavities were performed by using Er:YAG at 300 mJ, 10 Hz, for 20 sec. Subsequently, all teeth were waterproofed and immersed in 2% methylene blue for 48 h in a vacuum environment. The samples were longitudinally sectioned, and microleakage was measured. ANOVA and the Fisher LSD test showed that GIV was less susceptible to microleakage than were the other groups (p < 0.05). Interestingly, the use of the Er:YAG with no focus showed superior dentinal tubule sealing in comparison with the other groups, even with or without root-end cavity and Nd:YAG application.

Temperature Response in the Pulpal Chamber of Primary Human Teeth Exposed to Nd:YAG Laser Using a Picosecond Pulsed Regime

OBJECTIVE

This study was conducted to analyze temperature variation in the pulpal chamber using the (Nd:YAG) picosecond-pulsed laser to promote ablation in enamel and dentin of primary teeth.

BACKGROUND DATA

Several previous studies reported the temperature rise in pulpal chamber during laser irradiation. Since there are no reports about pulp chamber temperature changes during irradiation with picosecond-pulsed laser, the purpose of our investigation is to quantify the intrapulpal temperature changes following picosecond-pulsed Nd:YAG laser irradiation of enamel and dentin of primary teeth.

METHODS

In this study, we used 10 intact primary exfoliated teeth: five molars and five incisors. We used a commercial neodymium:- yttrium-aluminum-garnet continuous-wave (CW)-pumped Q-switched and mode-locked Nd:YAG laser, with varying power levels (200, 300, and 350 mW) operating with 100-psec pulsed duration.

RESULTS

Typical plots show differences between heating and cooling of enamel and dentin of anterior and posterior teeth. Whereas for enamel the time evolution curves are dependent on power used for the investigated range (200-350 mW), for dentin the differences are not so evident. Observing temperature enhancement for each power, we were able to analyze operational conditions where temperature changes do not exceed 5.5 degrees C. Power-time-temperature (PTT) diagrams for clinical operations were determined based on varying power level and exposition time. Through the heating-cooling cycle, we could extract conventional heating and cooling times for enamel and dentin.

CONCLUSION

We have shown that the Nd:YAG picosecond-pulsed laser is a safe tool for ablation of primary teeth in a broad range of operational parameters.