Analysis of Factors Affecting the Degree of Difficulty in Total Mesorectal Excision for Rectal Cancer: Investigation of the Factors Affecting Incomplete Resection and the Resection Time

ABSTRACT

PURPOSE: The aim of this study was to estimate the degree of difficulty in total mesorectal excisions (TMEs) for rectal cancer by using statistical methods after analysis of factors affecting the resection time and incomplete resection. METHODS: A total of 63 patients who underwent a total mesorectal excision for rectal cancer were evaluated. MRI pelvimetry data {(transverse diameter (TD), obstetric conjugate (OC), interspinous distance (ID), sacrum length (SL), sacrum depth (SD)}, tumor size (TS), T stage, and body mass index (BMI) were prospectively analyzed. A stepwise multiple regression analysis was performed to determine the operating time prediction equation by using these variables, and the differences in the mean operating time hased on gross evaluations of each specimen were analyzed. RESULTS: A stepwise multiple regression with the operating time as a dependent variable led to the following equation: Operation time (min)=35.726-2.162xTD (cm)-2.324 x OC (cm) + 2.671 x SL (cm) + 1.274 x TS (cm), with r2=0.533 and SEE=5.438. The mean operating time according to a gross evaluation of the TME specimen was 20.0 +/- 7.3 min in complete TME cases (n=42) and 27.9 +/- 7.2 min in incomplete TME cases (n=21) (P<0.001). CONCLUSIONS: MRI pelvimetry data (TD, OC, SL) and tumor size were factors affecting the operation time in TMEs for rectal cancer, and the operating time could be predicted by using the equation of the present study. Also, the mean operating time in incomplete TME cases was longer than that in complete TME cases. Thus, the degree of difficulty of an operation for rectal cancer can be predicted by using these factors.