Comparative study of the clinical, histological, and biological characteristics of squamous cell carcinomas in areas previously treated with photodynamic therapy.

Although photodynamic therapy (PDT) is an effective treatment option for non-melanoma skin cancer, the development of aggressive tumours in PDT-treated areas has been described. To evaluate the clinical, histological, and biological characteristics of squamous cell carcinomas (SCCs) in areas previously treated with PDT vs those arising in areas never treated with this therapeutic modality. A retrospective observational study was designed.

Combined Treatments with Photodynamic Therapy for Non-Melanoma Skin Cancer.

Non-melanoma skin cancer (NMSC) is the most common form of cancer in the Caucasian population. Among NMSC types, basal cell carcinoma (BCC) has the highest incidence and squamous cell carcinoma (SCC) is less common although it can metastasize, accounting for the majority of NMSC-related deaths. Treatment options for NMSC include both surgical and non-surgical modalities.

Isolation and characterization of PDT-resistant cancer cells.

Even though the efficacy of photodynamic therapy (PDT) for treating premalignant and malignant lesions has been demonstrated, resistant tumor cells to this therapy occasionally appear. Here, we describe the published methods to isolate resistant cancer cells to PDT and propose new procedures that may be used, as laboratory models allow a better understanding of resistance mechanisms. For this purpose, the treatment conditions, the photosensitizer (PS) or pro-drug, the cell line and the final selection - clonal of total population - must be taken into account.

Cellular intrinsic factors involved in the resistance of squamous cell carcinoma to photodynamic therapy.

Photodynamic therapy (PDT) is widely used to treat non-melanoma skin cancer. However, some patients affected with squamous cell carcinoma (SCC) do not respond adequately to PDT with methyl-δ-aminolevulinic acid (MAL-PDT) and the tumors acquire an infiltrative phenotype and became histologically more aggressive, less differentiated, and more fibroblastic. To search for potential factors implicated in SCC resistance to PDT, we have used the SCC-13 cell line (parental) and resistant SCC-13 cells obtained by repeated MAL-PDT treatments (5th and 10th PDT-resistant generations).