Effect of Photofrin II as a radio-sensitizing agent in two different oesophageal carcinoma cell lines

Background and Purpose: In spite of major advances in cancer treatment, the prognosis of patients with oesophageal carcinoma remains poor. Squamous cell carcinoma and adenocarcinoma account for 95% of all oesophageal tumors, although other histological subtypes are occasionally seen. We aimed to evaluate whether Photofrin II can enhance the effect of ionizing radiation on oesophageal cancer in an in vitro tumor model. Material and Methods: A human oesophageal squamous cancer cell line (OE-21) and a human oesophageal adenocarcinoma cell line (OE-33) were evaluated with and without incubation with Photofrin II. Cells were irradiated using doses ranging from 0 to 8 Gy. The response rate of the cells to irradiation was evaluated by a tetrazolium-based colorimetric assay, similar to the MTT test, with the aim to determine the efficiency of Photofrin II as a radiation sensitizer in comparison to irradiation alone. Results: The OE-21 cell line demonstrated a significantly reduced cellular survival rate, when irradiated in the presence of Photofrin, as compared to a control group irradiated in the absence of Photofrin II. For the OE-33 cell line, no significant differences were found between the group treated with Photofrin II and the control group. Conclusion: Our results demonstrate in an in vitro model that Photofrin II may act as a radio-sensitizer in squamous cell oesophageal cancer, but not in oesophageal adenocarcinoma.