Study On Photodynamic Therapy Of Human Gastric Cancer Using 5-aminolevulinic Acid

Gastric cancer is the second leading cause of cancer-related deaths worldwide, whose treatment depends largely on radical resection of the primary tumor. The available treatment using surgery, chemotherapy and radiation therapy results in less than 20% of five-year survival rate because 60%-80% of these patients suffer from advanced gastric cancer.As a new clinical treatment modality for cancer in addition to chemotherapy and radiotherapy, photodynamic therapy (PDT) is based on preferential accumulation of photosensitizers in the tumor, which, when absorbing light of appropriate wavelengths, produce cytotoxic oxygen product to cause direct cell death and/or vascular shutdown. PDT has been used successfully in the treatment of a wide variety of localized malignancies and may prove useful as an adjuvant therapy of gastric cancer.Porphyrins, a kind of traditional photosensitizer, such as hematoporphyrin derivative and Photofrin have been used almost exclusively in clinical PDT trials. Although favorable results have been reported by a number of clinicians, these photosensitizers have several drawbacks that may limit their applicability in certain situations. For example, the uncommonly long period of cutaneous photosensitization (lasting up to several weeks, even 18 weeks) was observed in patients following...