The Clinical Analysis Of Rectal Gastrointestinal Stromal Tumors

Purpose To describe the clinical, pathological and immunohistochemical characteristics of rectal GISTs (Gastrointestinal stromal tumors), and the correlation with clinical outcomes.Method A retrospective review of 29 patients with surgically treated rectal GISTs during the period from 1997 to 2005 was undertaken. The NIH (National Institutes of Health Consensus) criteria were applied.Results All the rectal GISTs in our series were arised in the lower half of rectum and underwent primary surgery of complete resections; High risk, intermediate risk, low risk and very low risk GISTs were found in 11, 6, 5 and 7 patients, respectively; Necrosis, adjacent (mucosal or serosa) invasion and marked pleomorphism were found in 10, 7and 20 patients, respectively. The positive expression of CD117, CD34, SMA and S-100 was found in 28, 28, 7 and 3 patients, respectively. 12 patients got recurrence or metastasis within the median disease-free survival time of 41 months. Among the patients underwent local resections, the recurrence for low and very lowrisk GISTs was only 1/10; while for intermediate and high risk GISTs, the recurrence after local resections was 3/4, higher than the recurrence and metastasis of 8/13 after laparotomy. Of the 12 patients with recurrence or metastasis, 4 patients underwent secondary complete resections; however, all the 4 patients recurred again. On univariable analysis, risk classification (p=0.0002), necrosis (p=0.0205), adjacent invasion (p=0.0090) and marked pleomorphism (p=0.0480) were significant predictors of disease-free survival. In the Cox regression model, only the risk classification (p=0.012) was found to be independent factor.Conclusion Our study showed that rectal GISTs arise predominantly in the lower half of rectum and have a very high CD117 and CD34 expression. Local resection may be a suitable choice for very low and low risk GISTs, but it is necessary to perform radical surgery for high and intermediate risk GISTs. For patients with recurrence, the prognosis of secondary surgery were poor. Among the factors of NIH risk classification, necrosis, adjacent invasion and marked pleomorphism, only the first one (NIH risk classification) was proved to be independent prognosis factor.