The pretreatment serum levels of the soluble receptors for tumor necrosis factor (p55 and p75 sTNFr) were retrospectively measured in 38 patients with endometrial cancer and 55 patients with benign uterine diseases as controls. Serum p55 and p75 sTNFr levels were significantly higher in patients with endometrial cancer (median = 2.4 ng/ml, range = 1.4-6.8 ng/ml, and median = 7.1 ng/ml, range = 2.5-19.5 ng/ml, respectively) than in controls (median = 1.7 ng/ml, range = 0.5-4.0 ng/ml, p < 0.0001, and median = 5.2 ng/ml, range = 2.6-21.9 ng/ml, p = 0.03, respectively). In the former, serum p55 and p75 sTNFr values correlated with the extent of disease (stage III-IV versus I-II: p = 0.04 and p = 0.03, respectively). Among the 23 patients with stage I endometrial cancer who underwent initial surgery, the preoperative serum levels of both receptors correlated with the histologic grade and myometrial invasion but not with the clinical outcome. In conclusion, a stage-dependent release of the soluble receptors for TNF into the bloodstream occurs in patients with endometrial cancer.