Evaluating photodynamic therapy protocols for high-grade cervical neoplasia: A comparative study

Cervical cancer has the infection by the Human Papillomavirus (HPV) as one of the main conditions for its development. Photodynamic Therapy (PDT) is a non-invasive treatment that combines the interaction between oxygen, light, and a photosensitizing molecule, resulting in cellular damage. HPV - infected cells because they are metabolically more active, can be better affected by this technique, promoting an alternative topic treatment for Cervical Intraepithelial Lesions (CIN). The present prospective and randomized study compared three PDT protocols applied to 31 patients with high-grade CIN and infected by HPV. Protocols used LEDs with a wavelength of 630 nm and a fluence of 150 J/cm² as a light source, with different number of sessions and intervals between the three groups. There was no statistical difference between the protocols, however, we noticed a clinical difference that indicates a better response to PDT in the treatment with two PDT sessions, and an interval of 21 days between sessions. In this protocol, after 120 days of therapy, 50 % of patients had a regression in the lesion, presenting cytology compatible with CIN I or chronic cervicitis and after 6 months there was an 80 % cure rate. Furthermore, 50 % of patients who, before treatment, were carriers of high-risk HPV had a complete viral load clearance. Therefore, we conclude that a greater number of sessions, as well as a longer interval between the treatments day, is an efficient method to enhance the results of PDT, allowing more time for regeneration and viral clearance of the cervical tissue.