Possibilities of photodynamic therapy in the treatment of malignant tumors of the oral cavity

Photodynamic therapy in treatment of squamous cell carcinoma of oral cavity with chlorine e6 photosensitizer with long-term follow up

Photodynamic therapy is an effective method for treating superficial forms of malignant neoplasms, characterized by a minimal risk of damage to normal tissues. In this study, we presented our experience of treating cancer of the oral mucosa using photodynamic therapy, and analyzed the immediate and long-term results of treatment. 38 patients with squamous cell carcinoma of oral cavity mucosa, with a depth of invasion no more than 7 mm, were included in the study. All patients underwent photodynamic therapy with chlorine e6 based photosensitizer. Photosensitizers were administered intravenously 3 hours before irradiation, at a dosage of 1 mg/kg of the patient’s weight. Photodynamic therapy was performed with the following parameters: P – 1.0 W, Ps – 0.31 W/cm2, E – 300 J/cm2. The area of one irradiation field ranged 1.0-2.0 cm2. Treatment effect was evaluated by RECIST 1.1. Overall survival, cancer-specific survival, and disease-free survival were calculated using Kaplan-Meier curves. Evaluation of adverse events was made by .TCAE 5.0 criteria. At 35 (92.1%) out of 38 cases, complete regression was observed after photodynamic therapy. Among them in 3 out of 35 patients relapse was diagnosed in 11.5 to 43.2 months. The total number of patients who didn’t respond to treatment was 6 (15.8%). Follow-up period was 4.2-87.3 months. (mean 42.9). 34 (89.5%) out of 38 patients are alive, 1 (2.6%) died from progression, and three died from other causes. The 5-year overall survival rate was 82.1%, cancer-specific survival rate was 97.0%, and disease-free survival rate was 81.1%. Among the factors significantly (p < 0.05) influencing relapse-free survival: depth of invasion < 5 mm (p – 0.013) and the presence of leukoplakia (p – 0.007). When assessing cancer-specific survival, factors worsening the prognosis were: age >70 years (p – 0.034) and the presence of leukoplakia (p – 0.007). Photodynamic therapy is an alternative treatment method of oral cancer superficial lesions, in case of proper assessment of primary lesion and in case of possibility of full irradiation of the tumor. Moreover, after using photodynamic therapy, the underlying connective-muscular structures are preserved, which promotes rapid healing with minimal scarring, the functions of the affected organ remain intact, and cosmetic defects do not form.

Photodynamic therapy treatment of oral cavity cancer in patients with comorbidities

We report the experience of radical treatment by photodynamic therapy of patients with squamous cell carcinoma of oral cavity with serious side diseases. Completed treatment of two patients with serious side diseases (HIV infection with associated pulmonary hypertension of high degree and cardiac pathology) suffered from cancer of oral cavity. Extensive surgical treatment and/or aggressive course of chemoradiation therapy were not indicated to them due to concomitant pathology. Both patients were diagnosed with squamous cell carcinoma of oral cavity, with appropriate stage Ist. сT1N0M0. Patients received treatment by photodynamic therapy with chorine photosensitizer in dose 1 mg/kg. Options of photodynamic were: output power – 1.5W, power density – 0.31 W/cm2, light dose – 300 J/cm2. After one time session of photodynamic therapy, in both cases full response was diagnosed (according to RECIST 1.1). In one case the second session of photodynamic therapy was performed due to concomitant disease of oral cavity – multiply lesions of leukoplakia and after was diagnosed full remission of all lesions. Major adverse event was pain during the first 5-7 days after treatment, curable by painkillers. Follow-up (IQR) was 12 and 18 month respectively with no evidence of progression. It is available to avoid extensive surgical treatment and aggressive course of chemoradiation therapy (as an alternative) with the use of photodynamic therapy. Photodynamic therapy is minimally invasive method of radical treatment of localized squamous cell carcinoma of oral cavity with minimal adverse events, and could be especially relevant in patients with serious concomitant diseases.

Photodynamic therapy in the treatment of extramammary paget’s disease

Extramammary Paget’s disease (EMPD) is a rare tumor that predominantly affects the skin containing apocrine glands. Due to insufficient data on the effectiveness of different methods, there is no single therapeutic approach to the treatment of patients with EMPD and their subsequent management. The use of surgical methods, laser therapy and local cytotoxic drugs has a number of limitations. The advantages of using photodynamic therapy (PDT) in EMPD are the absence of systemic toxicity, non-invasiveness, selectivity of action, the absence of carcinogenic potential, the possibility of conducting several courses of treatment, and good cosmetic results. In our review, we analyzed those published in 2000-2022 data on the results of PDT treatment of 114 patients with EMPD. As a result of treatment, complete regression of tumor foci was achieved in 40% of patients. Most authors note that PDT is more effective for small areas (up to 4 cm2).

Study of energy transfer processes between rare earth ions and photosensitizer molecules for photodynamic therapy with IR-excitation

Today, photodynamic therapy is one of the most promising minimally invasive methods of treatment of various diseases, including cancer. The main limitation of this method is the insufficient penetration into the tissue of laser radiation used to activate photosensitizer molecules, which makes it difficult to carry out therapy in the treatment of large or deep-seated tumors. In this regard, there is a great interest in the development of new strategies for photodynamic therapy using infrared radiation for excitation, the wavelengths of which fall into the “transparency window” of biological tissues. In this work, it was proposed to use upconversion NaGdF4 :Yb:Er nanoparticles (UCNP), which absorb infrared excitation and serve as a donor that transfers energy to the photosensitizer. Photosens and phthalosens were chosen as the most promising photosensitizers for the study. The aim of this work was to study the energy transfer processes between upconversion nanoparticles doped with rare-earth ions and photosensitizer molecules. in order to excite photosensitizers with IR radiation and carry out photodynamic therapy of deep-seated neoplasms. Using spectroscopic and time-resolved methods, it has been demonstrated that there is an efficient energy transfer between upconversion particles and photosensitizers phthalosens and photosens. The calculated efficiency of energy transfer by the Foerster mechanism was 41% for the UCNP + photosens system and 69% for the UCNP + phthalosens system. It has been experimentally and theoretically proved that there is a binding of photosensitizer molecules with UCNP by means of surfactants, leading to a reduction in the distance between them, due to which effective nonradiative energy transfer is realized. The generation of singlet oxygen by the phthalosens photosensitizer upon excitation by means of energy transfer from UCNP, excited at 980 nm wavelength of, has been demonstrated.