Preoperative ultrasound study in predicting lymph node metastasis for endometrial cancer patients

The objective of this study was to evaluate the efficacy of preoperative ultrasound (US) findings such as tumor size, status of myometrial invasion, and intratumoral "resistance index" (RI) in predicting lymph node metastasis in endometrial carcinoma patients.

Forty-two patients with endometrial cancer were enrolled. All patients underwent total abdominal hysterectomy, pelvic lymph node dissection or sampling, and para-aortic lymph node sampling. Two-dimensional and color Doppler US were performed before surgery to measure tumor size, depth of myometrial invasion, and intratumoral arterial RI. Formalin-fixed, paraffin-embedded pathologic slides from surgical specimens were reviewed by a senior pathologist to evaluate histologic type and grade, depth of myometrial invasion, cervical involvement, lymph-vascular emboli, and status of lymph node metastasis.

There were 12 patients with pelvic and/or para-aortic lymph node metastases and 30 patients without nodal metastases. Patients with tumors larger than 2.5 cm by US (11/12 vs 14/30, P = 0.008), more than half myometrial invasion by US (9/12 vs 5/30, P < 0.001), and intratumoral RI values less than 0.4 by US (12/12 vs 4/30, P < 0.001) had a significantly higher incidence of nodal metastases as compared with patients with tumors smaller than 2.5 cm, no or superficial myometrial invasion, and RI values higher than 0.4, respectively. Multiple regression analysis showed that only intratumoral RI values less than 0.4 were significantly correlated with nodal metastasis (P < 0.001, r2 = 0. 650). We used the intratumoral RI value as the parameter to evaluate nodal metastasis in endometrial cancer patients. Twelve of sixteen patients with intratumoral RI values <0.4 had a high incidence of nodal metastases. None of the 26 patients with intratumoral RI values >0.4 had nodal metastases.

Preoperative ultrasound features can offer important information for predicting lymph node metastasis in endometrial cancer patients. Patients with tumors with intratumoral RI values less than 0.4 should be highly suspected of having lymph node metastases and further management such as pelvic lymph node dissection or postoperative pelvic radiotherapy would be needed for these patients.