Successes of photodynamic therapy in treatment of erythroplasia of Queyrat

Abstract

The review is dedicated to the analysis of the effectiveness of the treatment of erythroplasia of Queyrat (EQ) using photodynamic therapy (PDT). Particular attention is paid to the relationship between EQ and human papillomavirus (HPV) infection. The data of various researchers are presented, confirming the correlation between the development of the EQ and the HPV infection, however, it is noted that due to the small number of studies it is difficult to draw reliable conclusions on the presence and strength of this connection. The mechanisms of PDT involved in the implementation of both the antitumor effect in the treatment of EQ and the antiviral effect against HPV are considered. The data of 12 clinical studies and observations of the results of PDT of the EQ conducted in recent years are analyzed. An analysis of literature data showed that in the treatment of EQ, one of the two photosensitizers is usually used locally: 5-aminolevulinic acid or 5-aminolevulinic acid methyl ester. The treatment parameters in all the analyzed studies were similar: exposure to the ointment for 3–5 hours followed by irradiation with a light dose of 37–105 J/cm 2 . The number of PDT courses in different studies varied from 1 to 19. The effectiveness of treatment varied widely in different studies and clinical observations. Most studies have demonstrated high efficacy of PDT with complete regression in 36–83% (100% in one study) and a relapse-free follow-up period of up to 51 months. However, there were also individual clinical observations of patients in whom the treatment with the method of PDT was ineffective. It is possible that the described results were associated with improperly selected regimes of PDT or a large lesion area. Most authors especially note a very good cosmetic effect and a complete absence of scars after the treatment. Thus, PDT is an effective and promising method for the treatment of EQ that requires, however, a more thorough development of the application regimen and a deeper study of the antitumor and antiviral components of the mechanism of action.