Photodynamic therapy: A new approach to treating human papillomavirus-associated cervical pathology

Objective. To develop methodological approaches to preventing human papillomavirus (HPV)-associated cervical precancer and cancer. Subjects and methods. The basis for the investigation was the results of treatment in 195 women infected with high-risk HPV genotypes, of whom there were 25 who were diagnosed with grade II dysplasia, 120 with grade III dysplasia, and 50 with cancer in situ. The terms grades II and III dysplasia accepted in the Russian literature, which the foreign literature denotes as CIN II-III, where CIN III encompasses grade III dysplasia and cancer in situ were used to characterize atypical changes in the cervical epithelium. A session of laser irradiation of the cervical canal was performed along its whole length, by applying a flexible quartz single-fiber light guide with a 3-cm-long cylindrical diffuser that gave a 360-degree light matrix. The vaginal portion of the cervix uteri was remotely irradiated using the light guide with a 1.-1.5-mm-diameter lens, which was perpendicularly brought to the organ. The investigators used a multipositional procedure for photodynamic exposure to a light spot from 1.5 to 1.5 cm in diameter when one-field irradiation was initiated from the mouth of the womb, by successively transferring the light spot along the entire surface of the cervix to overlap the neighboring fields by 0.3-0.4 cm and to capture intact tissues by 0.3-0.5 cm. Analysis of the immediate results of photodynamic therapy (PDT) with photosens (0.3 mg/kg, 24-hour exposure, a 100-J/cm 2 light dose) for grade II HPV-associated cervical dysplasia indicated that all clinical cases had been cured, regardless of the location of abnormal cervical epithelial changes. A complete regression of precancer was achieved in 92.5% of the women with grade III HPV-associated dysplasia who received PDT with photoheme (3.0 mg/kg, 72-hour exposure, a 150-J/cm 2-light dose) and photosens (0.3 mg/kg, 24-hour exposure, a 150-J/cm 2-light dose). The therapeutic effectiveness was found to be high in involvement of the exocervix (96.8%) and slightly beneath the exo-endocervix (90%). 200- and 250-J/cm 2 light doses were used in PDT with photoheme (3.0 mg/kg) and photosens (0.3 mg/kg) to treat cases of cancer in situ. A complete regression was achieved in 80.7% of the women; initial tumor changes were most commonly located in the exocervix (93.9%). Sporadic ineffective treatment cases were diagnosed predominantly when carcinoma in situ was present in the endocervix. Conclusion. Thus, PDT with the Russian agents photosens and photoheme is the minimal organ-sparing treatment for grades II and III HPV-associated dysplasia and precancer of the cervix uteri, which is similar to conventional therapies. The findings of the antiviral efficiency of PDT are of great interest in the context of the proven etiological role of HPV in the development of cervical cancer.

photodynamic therapy, cervical cancer, cervical intraepithelial neoplasia I, cervical intraepithelial neoplasia II, cervical intraepithelial neoplasia III, human papillomavirus, papillomavirus infection, alasens, photoditazin, photoheme, photosens