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Incidence and risk factors for pelvic lymph node metastasis in early-stage endometrial cancer: a retrospective study

Objective: We aimed to determine the incidence and risk factors of pelvic lymph node metastasis in patients with presumably early-stage endometrial cancer in a hospital in Hong Kong. Methods: We retrospectively reviewed medical records of patients with endometrial cancer confined to the uterus who underwent total hysterectomy with bilateral salpingo-oophorectomy, with or without pelvic lymphadenectomy at Tuen Mun Hospital between 1 January 2011 and 31 December 2015. Patients with gross uterine serosa involvement, extrauterine disease, synchronised ovarian cancers, or sarcomatous tumour (adenosarcoma and endometrial stromal sarcoma) were excluded. Pelvic lymph node metastasis is defined as the presence of metastasis in the excised lymph nodes or within 12 months if pelvic lymphadenectomy was not performed. Results: Of 268 patients (mean age, 54.8 years), 249 (92.8%) had endometrioid or mucinous adenocarcinoma, 14 (5.3%) had serous or clear cell carcinoma, and 5 (1.9%) had carcinosarcoma. Overall, 33 (12.5%) patients had highgrade pathology. 179 (66.8%) patients underwent pelvic lymphadenectomy with a mean of 25.2 (range, 7-85) pelvic lymph nodes removed; 16 of them had pelvic lymph node metastasis. Among the remaining 89 patients with no pelvic lymphadenectomy, 14 had selective lymph node sampling and 2 of them had pelvic lymph node metastasis. The incidence of pelvic lymph node metastasis in our cohort was 6.7% (n=18). In univariate logistic regression, large tumour size, deep myometrial invasion, cervical stromal invasion, and lymphovascular space invasion were significant risk factors of pelvic lymph node metastasis. In multivariate logistic regression, only large tumour size (adjusted OR=9.18, 95% CI=1.12-75.48, p=0.039) and cervical stromal invasion (adjusted OR=5.14, 95% CI=1.7215.3, p=0.003) were significant independent risk factors. Conclusion: Large tumour with maximal tumour diameter >2 cm and cervical stromal invasion are independent risk factor for pelvic lymph node metastasis in patients with early-stage endometrial cancer. Pelvic lymphadenectomy may not be necessary in patients with small tumour and absence of cervical involvement, especially when there is no evidence of high-grade pathology or deep myometrial invasion.