What nodal regions should be included in the treatment plan for endometrial cancer?

Nodal Regions to Include in Endometrial Cancer Treatment

For endometrial cancer, pelvic lymph nodes from the external iliac, internal iliac, obturator, and common iliac regions should be included in the treatment plan, with para-aortic nodal evaluation from the inframesenteric and infrarenal regions for high-risk tumors. 1

Standard Nodal Regions for Surgical Staging

• Pelvic lymph nodes from the external iliac, internal iliac, obturator, and common iliac regions should be routinely included in surgical staging for endometrial cancer 1
• Para-aortic nodal evaluation from the inframesenteric and infrarenal regions should be included for high-risk tumors (deeply invasive lesions, high-grade histology, serous adenocarcinoma, clear cell adenocarcinoma, or carcinosarcoma) 1
• For comprehensive surgical staging, para-aortic lymph node dissection should extend up to the renal vessels 1

Risk-Based Approach to Lymphadenectomy

Low Risk Disease

• For low-risk disease (G1/2 and myometrial invasion <50%), sentinel lymph node dissection (SLND) can be considered for staging 1
• Visual evaluation of peritoneal, diaphragmatic, and serosal surfaces with biopsy of suspicious lesions is important to exclude extrauterine disease 1

Intermediate and High Risk Disease

• For intermediate risk (G3 and myometrial invasion <50% or myometrial invasion >50%) and high-risk disease, lymphadenectomy is recommended to guide staging and adjuvant therapy 1
• Excision of suspicious or enlarged lymph nodes in the pelvic or para-aortic regions is important to exclude nodal metastasis 1

Special Histologic Considerations

• Omental biopsy is commonly performed in tumors with serous adenocarcinoma, clear cell adenocarcinoma, or carcinosarcoma histology 1
• For non-endometrioid histologies (serous, clear cell, undifferentiated carcinoma, or carcinosarcoma), more comprehensive nodal evaluation is warranted 1

Radiation Treatment Fields

• For patients with positive nodes, radiation therapy should be directed to the involved nodal distribution 2
• Patients with involved para-aortic nodes should receive extended field radiation 2
• For patients with cervical stromal invasion, the presacral lymph node region should also be included in the clinical target volume 1, 3

Sentinel Lymph Node Mapping

• Sentinel lymph node (SLN) mapping may be considered (category 2B) in selected patients 1
• SLN mapping can reduce false-negative rates when a predefined algorithm is followed 4
• SLN mapping allows for ultrastaging, which can detect low-volume metastases that might be missed with standard techniques 5, 4

Radiation Dose Considerations

• For clinically involved lymph nodes treated with chemoradiotherapy, a dose of at least 55 Gy in 25 fractions appears adequate for nodal control 6
• Nodal control rates are significantly higher with adequate radiation doses (96% 3-year control rate with appropriate dosing) 6

Common Pitfalls and Caveats

• Failure to perform adequate para-aortic lymph node evaluation in high-risk cases may lead to understaging and inadequate treatment 1
• Relying solely on imaging for nodal assessment without surgical evaluation may result in missed nodal disease 2
• Some patients may not be candidates for lymph node dissection due to medical comorbidities, and alternative treatment approaches should be considered 1
• PET/CT appears to be superior to CT alone for nodal staging, as para-aortic failure rates are significantly higher with CT-based staging compared to PET/CT-based staging in patients treated with pelvis-only chemoradiotherapy 6