Stage is the most important prognostic factor in endometrial cancer, the most common female genital malignancy in the United States. Other risk factors include tumor grade, lymph-vascular space invasion (LVI), and myometrial invasion, but the importance of tumor in the lower uterine segment (LUS) remains uncertain. LUS disease does correlate with lymph node involvement, which itself is a prominent prognostic factor.
This retrospective study was planned to learn the significance of LUS involvement in women having endometrial cancer but pathologically negative lymph nodes. Of 147 patients who underwent surgical staging for endometrial cancer in the years 1999–2004 and who had no diseased lymph nodes, 57% had LUS involvement by endometrial cancer. Follow-up intervals averaged 74 and 73 months, respectively, for patients with and those without LUS disease.
Patients with LUS invasion had higher rates of deep myometrial invasion and LVI. They also had a higher rate of nonendometrioid histology, although this difference was not statistically significant. Patients with and those without LUS disease were similar in age. Neither progression-free survival (PFS)—the primary end point—nor overall survival differed significantly with regard to LUS involvement. PFS averaged 70 months in women with LUS disease and 63 months in the others. Survival rates did not differ significantly when patients with endometrioid and high-risk histologies were analyzed separately. The risk of recurrence correlated with LUS disease on univariate analysis but not on multivariate analysis. The only factor correlating significantly with the risk of recurrence after multivariate analysis was LVI.
Involvement of the LUS by endometrial cancer does not predict a worse outcome in patients with pathologically negative lymph nodes. Any apparent prognostic role for LUS disease probably reflects its strong association with spread of disease to lymph nodes. If LUS disease is discovered during staging surgery, complete nodal dissection may preclude the need for postoperative radiotherapy in node-negative patients.