Frequency of lymph node involvement in clinically early-stage low-grade serous ovarian cancer: a systematic review and meta-analysis.

OBJECTIVE

The objective of this systematic review and meta-analysis was to estimate the incidence of lymph node metastasis among patients with clinically early-stage (International Federation of Gynecology and Obstetrics 2014 stage I-IIA) low-grade serous ovarian carcinoma undergoing primary surgical treatment.

METHODS

Registered in International Prospective Register of Systematic Reviews (CRD420251165472), this systematic review was conducted in accordance with the Meta-analysis of Observational Studies in Epidemiology guidelines. We searched Ovid MEDLINE, Embase, and Web of Science from inception through September 2025. Eligible studies included patients with pathologically confirmed low-grade serous ovarian carcinoma who were clinically presumed to have International Federation of Gynecology and Obstetrics 2014 stage I to IIA disease at surgery and underwent primary surgical management with pelvic and/or para-aortic lymph node dissection. We conducted a meta-analysis of single proportions to estimate the pooled rate of lymph node metastasis. Study-specific proportions (events/total) were pooled using an inverse-variance random-effects model with Freeman-Tukey double-arcsine transformation and back-transformed to proportions with 95% confidence intervals. Subgroup analyses excluded registry-based studies, studies at high risk of bias, and stage II disease.

RESULTS

Among 129 screened records, 8 studies met the inclusion criteria after full-text review. Overall, 77 patients had lymph node metastasis, corresponding to a pooled incidence of lymph node metastasis of 9.6% (95% confidence interval 4.4% to 16.0%; I2 58.8%). In the 3 studies reporting stage migration attributable only to nodal disease, 16 of 153 patients were upstaged, yielding a pooled upstaging proportion of 10.0% (95% confidence interval 5.6% to 15.5%; I2 30.6%). Subgroup analyses showed no statistically significant differences associated with these factors. None of the included studies provided perioperative complication rates for lymphadenectomy.

CONCLUSIONS

Approximately 1 in 10 patients with clinically early-stage low-grade serous ovarian carcinoma harbors occult nodal metastasis. These findings support discussing lymph node assessment as a source of staging information during preoperative counseling and individualized surgical planning. The prognostic and therapeutic value of identifying isolated nodal disease and the morbidity trade-offs in this setting remain unclear.