The role of diffusion magnetic resonance imaging in determining tumor aggressiveness during preoperative surgical planning in early-stage endometrial cancer.

PURPOSE: The present study aimed to evaluate the relationship between tumor volume and apparent diffusion coefficient (ADC) in preoperative magnetic resonance imaging and deep myometrial invasion, tumor grade, and lymphovascular space invasion (LVSI) in patients with early-stage endometrial cancer. METHODS: The study included 73 patients diagnosed with early-stage endometrial cancer based on histopathological examination between May 2014 and July 2019. Receiver operating characteristic (ROC) curve analysis was used to estimate the accuracy of ADC and tumor volume in predicting the LVSI, the depth of myometrial invasion (DMI), and the histopathological tumor grade in these patients. RESULTS: The areas under the ROC curves (AUCs) of ADC and tumor volume in predicting LVI, DMI, and high tumor grade were significantly greater than those for superficial myometrial invasion and low-grade tumors. The ROC analysis revealed that higher tumor volume was significantly associated with the prediction of DMI and tumor grade (p = 0.002 and p = 0.015). The corresponding cut-off values of tumor volume were > 7.12 and > 9.38 mL. The sensitivity of ADC in predicting DMI was higher than its sensitivity in predicting LVSI and grade 1 tumors. Furthermore, tumor volume was significantly associated with the prediction of DMI and tumor grade. CONCLUSION: In the absence of pathological pelvic lymph nodes in early-stage endometrial cancer, tumor volume in DWI sequences determines the active tumor load and tumor aggressiveness. Furthermore, a low ADC indicates deep myometrial invasion and helps differentiate stage IA and stage IB tumors.