Fraction of LOH on chromosome 17 and 18 (LOH-ratio) predicts colorectal cancer outcome

Abstract

20114 Background: Identification of patients at high risk for recurrence remains a central issue in the treatment of colorectal cancer. Our goal was to identify predictive factors for recurrence in colorectal cancer patients. Methods: DNA from 84 colorectal cancers were analyzed for wide-ranging allelotyping. Using 27 microsatellite markers spanning every 10cM on chromosome 17 and 18, we defined the LOH-ratio as the proportion of markers which show LOH out of 27 markers. Tumors were grouped into two groups by the median value of LOH-ratio (0.19). Recurrence free survival was compared with Kaplan-Meier analysis and log rank statistic. The Cox proportional hazards regression model was used for both univariate and multivariate analysis of recurrence free survival. Results: Log rank statistic revealed that LOH-ratio, stage, lymph node metastasis significantly related to recurrence free survival. On univariate analysis, significant predictors of Recurrence free survival were LOH-ratio, lymph node metastasis, Dukes’ classification, and pathological type. On multivariate analysis, LOH-ratio (HR 3.1, p = 0.02) and lymph node metastasis (HR 5.2, p = 0.002) independently predicted for recurrence free survival. Conclusions: LOH-ratio and lymph node metastasis were the only independent predictors of recurrence free survival. Altogether with lymph node metastasis, LOH-ratio could help to improve postoperative surveillance and adjuvant therapy. No significant financial relationships to disclose.