Regional Control and Chemoradiotherapy Dose Response for Clinically Involved Lymph Nodes in Patients with Locally Advanced Endometrial Cancers Who are Not Candidates for Upfront Surgical Staging Extrafascial Hysterectomy

Aims: There are limited data in endometrial cancer for nodal control and appropriate treatment volume for non-surgically resected nodes treated with chemoradiotherapy (CRT) for patients who are not candidates for upfront extrafascial hysterectomy.

Materials and methods: Patients (n = 105) with clinical stage ≥ II endometrial cancer who were not candidates for upfront extrafascial hysterectomy treated with preoperative CRT were retrospectively reviewed. CRT included pelvic nodes to the common iliac for node-negative disease and para-aortic nodes to the renal vessel for any node-positive disease. Involved nodes most commonly received a boost of 55 Gy in 25 fractions ± additional 4-6 Gy sequential boost for nodes >2 cm.

Results: Of the included 95 patients, 55 patients were node positive, with a total of 300 positive nodes. At a median follow-up of 25 months (interquartile range 9-46), the 3-year regional control was 91%. The 3-year involved nodal control rate was 96%. Involved nodal control was significantly higher in type I histology, nodes <2 cm and by radiation dose (75% for <55 Gy, 98% for 55 Gy in 25 fractions and 89% for >55 Gy, P = 0.03). The 3-year para-aortic failure rate for node negative patients treated with pelvis-only CRT was significantly higher with positron emission tomography/computed tomography (PET/CT) versus computed tomography (CT)-based staging (0% versus 20%).

Conclusion: This is the largest study examining regional control rates of involved lymph nodes with CRT for patients who were not candidates for upfront extrafascial hysterectomy. Nodal failure was low following CRT and dose ≥55 Gy in 25 fractions seems to be adequate for involved nodes.