Lymph Node Dissection in Early-Stage Ovarian Cancer: A Detailed Overview

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1. Lymphatic Drainage of the Ovary

Diagram

Pathways (Three Main Routes)

• Lymphatics travel alongside the ovarian vessels through the infundibulopelvic ligament
• Drain into the lateral aortic (para-aortic) and preaortic lymph nodes at the level of the renal vessels (L1-L2)
• This is the dominant pathway - explains why isolated para-aortic metastasis can occur without pelvic node involvement
• The right ovarian vein/lymphatics drain into nodes around the inferior vena cava; the left side drains into nodes alongside the left renal vein

• Lymphatics pass through the broad ligament following the uterine drainage
• Drain into the external iliac, internal iliac (hypogastric), obturator, and common iliac nodes
• Less dominant, but responsible for isolated pelvic node positivity

• A minor accessory route traveling alongside the round ligament
• Drains into superficial inguinal nodes
• Rarely clinically significant in ovarian cancer

Key clinical implication: Because para-aortic drainage predominates and can be involved in isolation (without pelvic node involvement), complete lymph node staging must include both para-aortic nodes up to the level of the renal vessels AND pelvic nodes. - Schwartz's Principles of Surgery, 11th Ed.; Campbell-Walsh Urology, 3-Vol Set

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2. FIGO Staging and the Role of Lymph Nodes

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3. Lymph Node Involvement Rates by Histology in Early-Stage Ovarian Cancer

Epithelial Ovarian Cancer (EOC)

• In a series of 142 systematically staged patients (Rodrigues Teixeira et al., Eur J Obstet Gynecol, 2022): overall positivity = 8.4%; HGSC = 10.4%, clear cell = 17.2%, endometrioid = 5.7%; no other histology (mucinous, LGSC, carcinosarcoma) had LN metastasis
• Chen et al. (2021, Front Oncol): overall occult LN metastasis rate = 7.1%; only 2.6% of apparent early-stage patients were upstaged by LN alone; mucinous/endometrioid low-grade tumors had minimal LN involvement
• Kim et al. (2023, Int J Gynecol Cancer): in 149 clinical stage I mucinous carcinomas, only 1 patient (0.7%) was upstaged by LN; lymphadenectomy had no survival benefit

Non-Epithelial Ovarian Cancer

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4. Role of Lymph Node Dissection in Early-Stage Ovarian Cancer

4A. Epithelial Ovarian Cancer (EOC)

Rationale FOR Lymphadenectomy

1. Staging accuracy and upstaging: Up to 29% of apparently early-stage EOC has occult nodal metastasis, particularly HGSC. Without lymphadenectomy, these patients receive inadequate treatment. A complete lymph node dissection will upstage approximately one-third of patients who appear clinically confined to the pelvis (Schwartz's Surgery, 11th Ed.)
2. Determination of adjuvant therapy: Stage IIIA1 disease (LN-only spread) now mandates different adjuvant chemotherapy intensity decisions compared to true stage I
3. Potential therapeutic benefit: Removing metastatic nodes may have cytoreductive benefit

Rationale AGAINST Routine Lymphadenectomy

1. Morbidity: Lymphedema (~10-15%), vascular injury, ureteric injury, chylous ascites, prolonged operative time, increased blood transfusion rates
2. Uncertain survival benefit in RCTs: Observational studies show benefit, but RCT evidence does not confirm survival advantage
3. Low yield in specific histologies: Mucinous, low-grade endometrioid tumors have minimal LN involvement

Evidence Summary

Histology-Specific Approach

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4B. Non-Epithelial Ovarian Cancer

Malignant Germ Cell Tumors (MOGCT)

• Dysgerminoma is lymphophilic and has the highest LN involvement (~25-30%), but even here, the excellent chemosensitivity of these tumors (BEP regimen) means that post-operative chemotherapy effectively treats occult nodal disease
• Lv et al. 2023 (PMID 37139156): No significant difference in OS (P=0.621) or DFS (P=0.332) between LND and non-LND groups in 340 MOGCT patients
• Current approach: Unilateral salpingo-oophorectomy + peritoneal staging + removal of grossly enlarged nodes only (not systematic LND). Since virtually all patients with stage IC or higher receive BEP chemotherapy, the therapeutic addition of systematic LND is negligible
• Fertility preservation is a major consideration - unnecessary retroperitoneal dissection adds risk without benefit in this young patient population

Sex Cord-Stromal Tumors (SCST)

• Very low nodal positivity (~1-3%); lymph nodes are rarely involved unless other sites of spread are present
• Billmire et al. 2025 (PMID 40516498): Tumor found in 3-10% of sampled sites, and only from grossly abnormal tissue - confirming that systematic sampling of normal-appearing nodes/tissue adds no staging information
• Current standard: Inspect and palpate all retroperitoneal nodes; remove only grossly enlarged or suspicious nodes; routine systematic LND is not indicated
• NCCN guidelines note that surgical staging for malignant sex cord-stromal tumors "generally doesn't include removing nearby lymph nodes" when they appear normal

Borderline Ovarian Tumors (BOT)

• LN involvement reported in ~15-20%, but these are usually non-invasive implants in lymph nodes (microscopic peritoneal spread), not true nodal metastasis
• Fan et al. 2021 (PMID 34119365): Systematic review and meta-analysis found that neither lymph node involvement nor lymphadenectomy significantly affected survival in BOT
• Current recommendation: No routine lymphadenectomy; remove enlarged/suspicious nodes only

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5. Sentinel Lymph Node Biopsy in Early-Stage EOC

• Para-aortic mapping: injection into the infundibulopelvic ligament - pooled detection rate 79.9% (95% CI 66.1-91.4%)
• Pelvic mapping: injection into the utero-ovarian ligament - pooled detection rate 42.7% (95% CI 28.5-57.3%) - significantly lower, limiting utility

• NPV: 100% for both para-aortic and pelvic regions
• Sensitivity: 97.8% (para-aortic), 100% (pelvic)

• Technetium-99m (99mTc) alone or combined with ICG had significantly higher detection rates than ICG alone
• Lower ICG volume (0.2-0.5 mL) performed better than 2 mL for both pelvic and para-aortic detection

• Low pelvic detection rates
• Lack of prospective validation
• Technical challenges related to ovarian anatomy vs. cervical/endometrial cancer

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6. Guideline Recommendations (2024-2025)

ESGO-ESMO-ESP Consensus 2024 (PMID 38307807)

• High-grade EC, CCC, high-risk mucinous (stage I-II): Complete surgical staging including TAH+BSO+omentectomy + systematic pelvic and para-aortic LND + peritoneal biopsies + cytology = standard procedure
• LGSC with non-invasive peritoneal implants: Complete removal of implants + peritoneal staging; removal of enlarged/suspicious nodes recommended; routine systematic LND is NOT recommended
• Low-grade mucinous (expansile type), low-grade endometrioid: Systematic LND may not be warranted given very low metastatic risk

• Systematic pelvic and para-aortic LND should NOT be performed if macroscopic complete intra-abdominal resection achieved and nodes are non-suspicious on imaging and intraoperatively
• Remove enlarged/suspicious nodes to achieve complete resection

NCCN Guidelines 2025

• Systematic lymphadenectomy recommended for staging purposes in early-stage EOC
• For clear cell carcinoma: systematic LND included in staging surgery
• For malignant sex cord-stromal tumors: staging surgery is recommended but "generally doesn't include removing nearby lymph nodes" when normal
• LND should extend to the level of the renal vessels (left renal vein)

NICE Guidelines (UK)

• Systematic retroperitoneal lymphadenectomy (pelvic + para-aortic) recommended only when disease is presumed confined to the ovaries
• Not recommended when peritoneal disease is already present

BGCS Guidelines (British)

• Pelvic and para-aortic LND permitted when no peritoneal spread and nodal status expected to influence adjuvant treatment
• More conservative in low-risk histologies (expansile mucinous, low-grade endometrioid)
• Frozen section to confirm malignancy is advised before lymphadenectomy

JSGO (Japan) and Summary Table

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7. Technical Aspects of Lymph Node Dissection

• Operative time increase: ~60-90 minutes
• Blood transfusion requirement significantly higher in LND group
• Surgery-related deaths: not significantly different
• Lymphedema, chylous ascites: 5-15%
• Grade ≥3 complications: ~4-5%

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8. Summary: Current Thinking

1. Observational data consistently show improved OS with LND, but this reflects confounding (LND patients were correctly staged and received appropriate chemotherapy)
2. RCT data do NOT show a direct survival benefit from LND as a therapeutic maneuver
3. The primary value of LND is staging accuracy - correctly identifying stage IIIA1 disease that would otherwise be undertreated
4. Histology drives risk: HGSC and CCC warrant systematic LND; mucinous/low-grade tumors do not

• SLN biopsy may replace full LND in the future, pending prospective validation
• Para-aortic SLN mapping via infundibulopelvic ligament injection is feasible and accurate; pelvic mapping remains suboptimal
• Molecular staging (peritoneal cytology + targeted biopsy) may increasingly complement or replace nodal assessment in low-risk histologies

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• Ledermann JA et al. ESGO-ESMO-ESP consensus on ovarian cancer. Ann Oncol 2024;35:248-266
• Chiyoda T et al. Lymphadenectomy for primary ovarian cancer: meta-analysis. J Gynecol Oncol 2020
• Yang C et al. Influence of lymphadenectomy in early-stage EOC: meta-analysis. BMC Womens Health 2023
• Zorzato PC et al. SLN biopsy in apparently early-stage EOC. Eur J Surg Oncol 2026
• Rey I et al. SLN biopsy diagnostic accuracy in early ovarian cancer. Int J Gynecol Cancer 2024
• Rodrigues Teixeira F et al. Impact of lymph node staging in presumed early-stage ovarian carcinoma. Eur J Obstet Gynecol 2022
• Lv B et al. Prognosis of lymphadenectomy in malignant ovarian germ cell tumor. Front Oncol 2023
• Billmire DF et al. Surgical staging for ovarian sex cord-stromal tumors. Eur J Obstet Gynecol 2025
• Chen J et al. Systematic LND may be abolished in low-grade mucinous/endometrioid EOC. Front Oncol 2021
• Kim SR et al. Lymphadenectomy in early-stage mucinous ovarian cancer. Int J Gynecol Cancer 2023
• Renz M, Friedlander M, Berek JS. Cancer of the ovary, fallopian tube, and peritoneum: 2025 update. Int J Gynaecol Obstet 2025
• Schwartz's Principles of Surgery, 11th Edition - FIGO staging and ovarian cancer surgical principles
• Campbell-Walsh Urology, 3-Vol Set - Ovarian lymphatic drainage anatomy