Unenhanced region on magnetic resonance imaging represents tumor progression in uterine carcinosarcoma

Objective: Carcinosarcoma of the uterine corpus has a poor prognosis. Although pathological necrosis is a prognostic factor of endometrial cancer, the clinicopathological influences of an unenhanced region observed on magnetic resonance imaging (MRI) are inconclusive. The aim of our study was to determine the clinicobiological impact of the presence of an unenhanced region on MRI, which can represent necrosis, in uterine carcinosarcoma. Methods: The clinicopathological factors of 29 patients diagnosed with uterine carcinosarcoma were assessed retrospectively. The percentage of the tumor that was unenhanced on MRI was determined. The clinicopathological factors related to the unenhanced regions were evaluated. The prognostic significance was assessed using the Kaplan-Meier method and Cox regression model. Results: Although the presence of pathological necrosis was not a poor prognostic factor (p=0.704), unenhanced regions on MRI correlated with poor prognosis when the unenhanced regions in the tumor accounted for more than 10% of the total tumor (p=0.019). The percentage of unenhanced regions was positively correlated with stage (p=0.028; r=0.4691) and related to tumor size (p=0.086; r=0.3749). The Cox regression analysis indicated that the presence of lymph node (LN) metastasis and more than 10% of the tumor being unenhanced on MRI were prognostic factors of overall survival in the univariate analyses (p=0.018 and p=0.047, respectively). Conclusion: The unenhanced region on MRI, which represents pathological necrosis, reflects tumor progression, and semi-quantification of the region is useful to predict the prognosis in patients with uterine carcinosarcoma.