Is there a prognostic difference between depth of myometrial invasion and the tumor-free distance from the uterine serosa in endometrial cancer?

The objective was to determine whether tumor-free distance from the uterine serosa is more predictive of patient outcome than depth of endometrial cancer invasion into the myometrium. Patients with surgically staged endometrial adenocarcinoma between 1997 and 2000 were identified. Depth of myometrial invasion (DOI) was identified defined as the distance between endometrial–myometrial junction and deepest myometrial invasion. Tumor-free distance from the uterine serosa (TFD) was defined as the distance between the serosa and deepest myometrial invasion. DOI and TFD were expressed as continuous variables and compared with traditional surgicopathologic variables, recurrence, and survival to determine their predictive and prognostic significance. We identified 153 patients who met study criteria. The median DOI was 0.5 cm and the median TFD was 1.4 cm. The most common stage was IB, and 23 patients had positive nodes. With a median follow-up of 29 months, 10 patients have recurred. When DOI and TFD were compared in a univariate model, TFD was an equal or more significant predictor of traditional surgicopathologic variables. TFD but not DOI was predictive of recurrence. Likewise, TFD was a more significant predictor of dying from disease than DOI. In a multivariate model, TFD was shown to correlate with surgicopathologic variables, recurrence risk, and survival. DOI, however, was not predictive unless myometrial thickness was included in the model. A TFD of 1 cm maximized the balance of sensitivity and specificity in predicting recurrence. TFD as a single measurement carries significant prognostic importance in women with comprehensively staged endometrial cancer.