e18005 Background: Evaluation the distribution of nodal metastases in the stage IB1 cervical cancer and the risk factors associated with pelvic lymph node metastasis (LNM) at each anatomic location. Methods: 728 patients with stage IB1 cervical cancer who underwent radical hysterectomies and systemic pelvic lymphadenectomies from January 2008 to December 2017 were retrospectively studied. All removed pelvic lymph nodes were pathologically examined, and the risk factors for LNM at the obturator, internal iliac, external iliac, and common iliac regions were evaluated by univariate and multivariate logistic regression analyses. Results: 20,134 lymph nodes were analysed with the average number of 27.80 (± SD 9.43) lymph nodes per patient. Nodal metastases were present in 266 (14.6%) patients. The obturator was the most common site for nodal metastasis (42.5%) followed by the internal iliac nodes (20.3%) and the external iliac nodes (19.9%), while the common iliac (9.8%) and parametrial (7.5%) nodes were the least likely to be involved. Tumor size more than 2 cm, histologically proven lymphovascular space involvement (LVSI) and parametrial invasion correlated independently significantly with the higher risk of the lymphatic metastasis. Obesity (BMI≥25) was independently significantly negatively correlated with the risk of lymphatic metastases. All the positive common iliac nodes were found in patients with tumors greater than 2 cm. The multivariate analysis showed that tumor size greater than 3 cm was associated with a 16.6-fold increase in the risk for common iliac LNM. Interestingly, tumor size was not an independent risk factor for pelvic LNM in the lower regions, i.e., the obturator, internal iliac and external iliac areas, where LVSI was the most significant predictor for LNM. In addition, parametrial invasion was related to external and internal iliac LNM; deep stromal invasion and age less than 50 years were associated with obturator LNM. Conclusions: The incidence of lymph node metastasis in patients with stage IB1 cervical cancer is low but prognostically relevant. The data offer the opportunity for tailored individual treatment in selected patients with small tumors and obesity.
Region-specific Risk Factors for Pelvic Lymph Node Metastasis in Patients with Stage IB1 Cervical Cancer
