Therapeutic effects of topical photodynamic therapy with 5-aminolevulinic acid on cervical high-grade squamous intraepithelial lesions

Background: Topical photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) is a non-invasive option for treatment of Cervical Intraepithelial Neoplasia (CIN). We investigated the clinical efficacy and safety of ALA-PDT in treatment of patients with cervical high-grade squamous intraepithelial lesion (HSIL) and evaluated the factors that effect the efficacy of PDT.

Methods: A total of 99 patients (average age: 30 years (18-45 years old)) with cervical HSIL and high-risk Human Papilloma Virus (hr-HPV) infections and who had received ALA-PDT were enrolled in this retrospective study. Before ALA-PDT, cervical exfoliated cells from all patients were obtained for HPV genotyping, liquid-based cytology test (LBC) and PAX1 methylation (PAX1^m) test. Then, 6 months after ALA-PDT, HPV genotyping, LBC and colposcopy-directed biopsy were conducted. During subsequent follow-up, HPV genotyping and LBC were performed, and colposcopy-directed biopsy was conducted if hr-HPV was positive and/or LBC result was abnormal.

Results: At 6 months after treatment, total HPV clearance and lesions complete remission (CR) rates were 64.6% (64/99) and 88.9% (88/99), while at 1-year of follow-up, they were 81.3% (65/80) and 92.5% (74/80), respectively. At 1-year follow-up, HPV clearance rate was higher, relative to 6 months after ALA-PDT (p <0.05). At 6 months after treatment, HPV clearance and CR rates in the PAX1 hypermethylation (PAX1^hm) group were 36.8% and 73.7%, which were lower compared to the rates for PAX1 hypomethylation (PAX1^lm) group (71.3%, 92.5%) (p <0.05). Moreover, of the 11 patients with cervical canal lesions, 3 (3/7, 42.9%) patients had cervical canal HSIL persistence and the other 4 cervical canal HSIL and all of the 4 cervical canal LSIL had complete remission.

Conclusions: ALA-PDT is an effective, safe treatment approach for patients with cervical HSIL and hr-HPV infections. Patients with PAX1^lm showed better therapeutic outcomes than patients with PAX1^hm or cervical canal HSIL.