Surgical Oncology net Blog aimed at residents in surgery     e mail surgoncnet@gmail.com

 

Blog aimed at residents in surgery

URL :  www.surgical-oncology.net             e mail surgoncnet@gmail.com

Photodynamic therapy in gastric cancer. Romeo Giuli MD, resident. School of General and Emergency Surgery. University of Siena.   Italy. August 2001.     Review Article. .     To the updating Photodynamic therapy is a form of cancer treatment and has a potentially important role either as a primary or adijuvant mode of treatment of tumours of the gastrointestinal tract. PDT initially involves the uptake or production of a photosensitive compound by tumour cells. Subsequent activation of the photoreactive compound by a specific wavelength of light results in cell death, either directly or as a result of vascular compromise and / or apoptosis. PDT shows considerable promise as a primary treatment modality for localized superficial tumours and is a potentially important form of adjuvant treatment for cancers of the GI tract. The major side effect of PDT is cutaneous photosensitization. The major limitation of PDT is depth of tumour kill. The advantages of PDT include the low incidence of complications, tumor responsiveness uncompromides by previous radiation or chemotherapy, subsequent use of radiation or chemotherapy, and repetition in multiple successive sessions. The use of photosensitive drugs has diagnostic applicability because photoreactive agents are also fluorescent, permitting tumour localization with a suitable imaging system. The clinical applications of PDT are just emerging in relation to the technologic advances ( 1 ). For example photosensitized patients are exposed to bright lights when undergoing intraoperative photodynamic therapy or fluorescence measurements. Acrylate yellow filters of operating lights might reduce unwanted tissue damage ( 2 ). PDT has found applicability in the treatment of malignant and benign tumours involving the skin, GI tract, retroperitoneum, genital and urinary systems, chest, central nervous system and eye. As with esophageal cancer, PDT for gastric cancer is performed using an endoscopic laser-light delivery system. Unfortunately the gastric rugae and mucosal folds can shadow other areas from light. Gastric tumours may also spread over a large surface area, making light delivery even more difficult. It is doubtful that PDT will ever be the primary treatment except in early gastric cancer ( 1 ). Hendren and collegues publish an initial report of their phase II trial designed to evaluate the effectiveness of surgical debulking and PDT in carcinomatosis and sarcomatosis. Photodynamic therapy combines photosensitizer drug, oxygen and laser light to kill tumour cells on surface. Photofrin PDT for carcinomatosis has been successfully administered to 42 patients, with acceptable toxicity. The median follow up of 21 months exceeds the expectations; however the relative contribution of surgical resection versus PDT is unknown. Deficiencies in photosensitizer delivery, tissue oxigenation, or laser light distribution leading to recurrences may be addressed through the future use of new photosensitizers ( 4 ). References 1) J Webber, M Herman, D Kessel, D Fromm. Current concepts in gastrointestinal photodynamic therapy. Annals of Surgery, vol 230; n1 12-23, 1999. 2) P Hinnen et al. Acrylate yellow filter in operating lights protect against photosensitization tissue damage. British Journal of Surgery 2000, 87, 231-235. 3) TW Bauer, S Hahn, F R Spitz, A Kachur, E Glatstein, DL Fraker. Preliminary report of photodynamic therapy for intraperitoneal sarcomatosis. Annals of Surgical Oncology 2001, 8 (3): 254-259. 4) Hendren SK, SM Hahn, FR Spitz, TW Bauer, SC Rubin, T Zhu, E Glatstein, DL Fraker. Phase II trial of debulking surgery and Photodinamic Therapy for disseminated intraperitoneal tumors. Annals of Surgical Oncology, 2001; 8(1): 65-67. TO HOME PAGE next article Surgical Oncology net