PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics At least 4 weeks since prior chemotherapy and recovered Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy and recovered Surgery: At least 4 weeks since prior surgery and recovered Other: At least 4 weeks since any prior therapy directed at malignant endometrial tumor(s) At least 4 weeks since prior folate-containing vitamins No concurrent folate-containing vitamins No other concurrent anticancer therapy