Prognostic significance of a preoperative magnetic resonance imaging assessment of the distance of mesorectal extension in clinical T3 lower rectal cancer.

PURPOSES

The aim of this study was to evaluate the association between the mesorectal extensions on high-resolution magnetic resonance imaging (MRI) and the prognosis of patients with clinical T3 lower rectal cancer.

METHODS

Fifty-eight patients with clinical T3 lower rectal cancer were investigated using high-resolution MRI. One radiologist who was blinded to the clinicopathological findings retrospectively examined the MRI-predicted circumferential resection margin (mrCRM) and the distance of mesorectal extension (mrDME) on the scans. If the imaging showed a tumor ≤1 mm from the mesorectal fascia, then the mrCRM involvement was defined as potentially present. The tumors were divided into two groups: mrDME ≤4 mm and mrDME >4 mm.

RESULTS

A survival analysis showed that mrCRM-positive patients had a significantly poorer prognosis in the RFS (p < 0.01) and LRFS (p < 0.01). Patients with mrDME >4 mm revealed a significantly poorer prognosis than those with mrDME ≤4 mm in the OS (p = 0.04), RFS (p < 0.01), and LRFS (p = 0.04). A multivariate analysis revealed that both mrCRM and mrDME on MRI had a significant impact on the RFS (p = 0.01 and 0.03, respectively).

CONCLUSION

The mrDME, as well as the mrCRM, may be an important preoperative prognostic factor for patients with clinical T3 lower rectal cancer.