Clinical significance of the mesorectal extension of XXXX : a Japanese multi-institutional study.

@entity5 @entity1 @entity2802
OBJECTIVE: The aim of this study was to emphasize the importance of a subclassification in the @entity2802 staging system of @entity5 . BACKGROUND: The clinical significance of the mesorectal extension of @entity5 is unclear. @entity1 AND METHODS: Data from 463 consecutive @entity1 with stage IIa disease (T3N0) undergoing curative surgery at 28 institutes were analyzed. The measurement of the distance of the mesorectal extension (DME) was histologically evaluated. Risk factors for recurrence, for the optimal cutoff point of the DME, independent prognostic factors, and for survivals were studied using receiver operating characteristic curve and logistic and Cox regression analyses. Survivals were calculated using the Kaplan-Meier method. RESULTS: A value of 4 mm was determined as the optimal cutoff point. The @entity1 were subdivided into 2 groups: DME  <= 4 mm and DME > 4 mm at the optimal cutoff point. DME > 4 mm had the greatest impact on recurrence-free survival [P = 0.00023, hazard ratio (HR): 2.26, 95% confidence interval (95% CI): 1.465-3.492, L/U ratio: 0.420] and was an independent adverse prognostic factor (P = 0.00323, HR: 1.97, 95% CI: 1.254-3.091). The distant metastasis rate in DME > 4 mm was higher 16.7% than that in DME  <= 4 mm (P = 0.00177, OR: 2.61, 95% CI: 1.430-4.761). The incidence of local recurrence was not influenced by DME. The recurrence-free 5-year survival rate in DME  <= 4 mm was significantly better than that in DME > 4 mm (86.6% vs 71.3%, P = 0.00015, HR: 0.44, 95% CI: 0.286-0.683). The @entity5 -specific survival rate in DME  <= 4 mm was also significantly better than that in DME > 4 mm (91.3% vs 82.2%, P = 0.000664, HR: 0.52, 95% CI: 0.325-0.843). CONCLUSIONS: A subclassification according to mesorectal extension based on a 4-mm cutoff point is needed for the @entity2802 staging system. However, further prospective study is necessary to prove reproducibility and validity of the cutoff point.
