Preoperative PET scanning among patients with high-risk, clinical stage 1 endometrial cancer (EC) may improve surgical management, especially for patients with extensive extra-uterine disease or nodal metastases beyond nodal basins, according to a study.

Gregory Sutton, MD, and colleagues conducted a single-center study of 144 patients treated between March 2017 and August 2021. They performed preoperative scans based on high-risk histology (serous, clear cell, carcinosarcoma, or high-grade endometrioid adenocarcinoma) or age (≥70) regardless of histology.

“Our optimal treatment of early EC is robotic hysterectomy with bilateral salpingo-oophorectomy and sentinel lymph node biopsy using indocyanine green and firefly imaging,” Dr. Sutton and colleagues wrote. “However, some management plans were changed based on PET scan results.  We did a retrospective analysis of these changes.”

PET Scans & Extra-Uterine Metastases

Researchers conducted preoperative PET scans on more than half of enrolled patients (N=77; 53.4%). Negative scans occurred in three patients (3.8%), including one participant who had a pyometra with a dilated endometrial cavity; the other two participants had scant residual at hysterectomy and one had a clear cell primary.

Most patients (N=57; 74%) had tumor uptake in the uterus only. Among these patients, 20 had non-metastatic uptake outside the uterus, including four with activity in the colon, three with benign thyroid nodules, three with osteoarthritis, one with a gastric gastrointestinal stromal tumor, and one with bilateral benign axillary activity.

Dr. Sutton and colleagues identified extra-uterine metastases in 17 patients, or 22.1% of those scanned.  Extra-uterine spread included nodal involvement in 11 patients, with pelvic and para-aortic in eight participants and isolated subclinical groin metastasis in one participant; pulmonary metastases in two patients and one with a synchronous undiagnosed lung primary; hepatic metastases in two patients; and bone metastases in two patients.

Based on PET scan findings, only three of the patients with metastatic disease underwent primary robotic surgery; one had a concomitant groin dissection and two underwent complete pelvic and para-aortic lymphadenectomy instead of sentinel nodes. Additionally, seven patients received neoadjuvant or palliative chemotherapy with or without radiotherapy and eight had open hysterectomies with extensive lymphadenectomies and/or cytoreduction.