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Intraepithelial Neoplasia Part 3

Tham khảo tài liệu 'intraepithelial neoplasia part 3', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Ocular Surface Squamous Neoplasia 51 However OSSN can be diffused or multifocal with borders that are difficult to detect clinically and there is also a chance for skipped areas from histopathologic examination. Reported recurrence rate after surgical treatment is significant range between 15 -52 . Lee Hirst 1995 Tabin et al. 1997 Sudesh et al. 2000 McKelvie et al. 2002 Incomplete excision with positive surgical margins has been identified as a major risk factor for recurrence. McKelvie et al. 2002 The more severe grades of OSSN appear to recur at higher rates. With adjunctive cryotherapy the recurrent rate appears to be reduced from 28.5 and 50 after simple excision to 7.7 and 16.6 after excision with cryotherapy in primary and recurrence OSSN respectively . Sudesh et al. 2000 The drawbacks of surgical treatment are complications resulted from the healing process particularly in advanced lesions including tissue granulation symblepharon pseudopterygium diplopia from tissue shortening blepharoptosis limbal stem cell deficiency and other complications. These surgical problems instigate further investigation into safer alternative treatments. 5.2.2 Chemotherapy Due to the relatively high rate of recurrence after surgical excision various topical treatments have been advocated as a sole therapy for OSSN. Topical therapy offers a nonsurgical method for treating the entire ocular surface with less dependence on defining the tumor margin potentially eliminating subclinical lesions. Topical treatment can offer a high drug concentration avoiding systemic side effects. Furthermore the increased cost stress pain and trauma associated with surgical procedures are avoided. Topical medications have been used effectively for treating this condition comprised of mitomycin C MMC 5-fluorouracil 5-FU and interferon with MMC used most commonly by a group of external disease specialists. Stone et al. 2005 These agents have been used as a sole therapy or a surgical adjuvant .