Percent surface area involvement is a predictor of lymph node metastasis in endometrial cancer

Objective.To determine if percent surface area involvement (SAI) of tumor in endometrial cancer is predictive of lymph node metastasis.Methods.A retrospective study was performed of all patients diagnosed with endometrial cancer at Magee Women's Hospital between January 1990 and December of 1995. Papillary serous and clear cell histologic subtypes were excluded. Pathology reports were reviewed for percent SAI, myometrial invasion, grade, histologic subtype, lymphvascular space invasion, and lymph node metastasis. Percent SAI was categorized into three groups: < 35%, 35–80%, and > 80%. The primary outcome variables were pelvic or periaortic lymph node metastasis. Univariate and multivariate analysis logistic regression models were used to determine predictors of nodal metastasis.Results.Of 558 patient records reviewed, 319 had lymph node dissections performed and 42 (13%) of those patients had positive lymph nodes. Two of 79 (3%) patients with < 35% SAI had lymph node metastasis, 17 of 165 (10%) patients with 35–80% SAI had lymph node metastasis, and 23 of 75 (31%) patients with > 80% SAI had lymph node metastasis. The percent SAI was significantly associated with lymph node metastasis (p < 0.001). Multivariate logistic regression indicated that for patients with > 80% SAI, the odds of having lymph node metastasis were 10.8 times (CI 1.3–90.4) that for patients with similar tumor histology, grade, and invasion, but < 35% SAI (p = 0.03). A subset analysis of patients with superficial myometrial invasion was performed and 16% of patients with < 50% myometrial invasion and > 80% SAI had positive lymph nodes, while only 1.4% of patients with < 50% myometrial invasion and < 35% SAI had positive lymph nodes (p = 0.02).Conclusion.Our analysis indicates that percent SAI is an independent risk factor for lymph node metastasis. Furthermore, assessing SAI with myometrial invasion gives a more accurate prediction of lymph node metastasis than myometrial invasion alone. This becomes clinically relevant when assessing risk factors for lymph node metastasis intraoperatively.