Topotecan in Treating Patients With Gynecologic Cancer That Cannot Be Removed by Surgery

DISEASE CHARACTERISTICS: * Histologically\* or cytologically confirmed unresectable gynecologic malignancy for which standard curative or palliative care is not available * All tumor types allowed NOTE: \*Histologic confirmation of recurrence is not required * Measurable or nonmeasurable disease * If CT scan was used to evaluate measurable disease, lesions must be clearly defined and be ≥ 10 mm on spiral CT scan * No "borderline tumors" or tumors with low malignant potential PATIENT CHARACTERISTICS: * Karnofsky performance status 60-100% * Life expectancy ≥ 12 weeks * ANC ≥ 1,500/μL * Platelet count ≥ 100,000/μL * Hemoglobin ≥ 9 g/dL * Creatinine ≤ 1.5 times upper limit of normal (ULN) * Creatinine clearance ≥ 60 mL/min * AST/ALT ≤ 2.5 times ULN (\< 5 times ULN if liver metastases are present) * Alkaline phosphatase ≤ 2.5 times ULN (\< 5 times ULN if liver metastases are present) * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Adequate intestinal function (i.e., no gastrostomy tube or requirement for IV hydration or nutritional support) * No severe gastrointestinal bleeding or intestinal obstruction * No other condition that would affect gastrointestinal absorption and motility * No septicemia, severe infection, or acute hepatitis * No other malignancies requiring chemotherapy or radiotherapy within the past 5 years, except skin cancer * No concurrent severe medical problem unrelated to the malignancy that would significantly limit full compliance with the study, expose the patient to extreme risk, or decrease life expectancy PRIOR CONCURRENT THERAPY: * At least 28 days since prior investigational drugs (including cytotoxic drugs) * At least 4 weeks since prior chemotherapy, radiotherapy, biologic therapy, or surgery and recovered * No more than 3 prior chemotherapy regimens * No prior topotecan hydrochloride or other camptothecin analogs * No prior radiotherapy to \> 25% of the bone marrow * No other concurrent chemotherapy, radiotherapy, biologic therapy, immunotherapy, or hormonal therapy for cancer * No concurrent administration of any of the following: * P-glycoprotein (ABCB1, Pgp, MDR1) inhibitors or inducers * Breast cancer-resistant protein (ABCG2, BCRP, MXR) inhibitors or inducers * No concurrent chronic H2 antagonists, proton pump inhibitors, or antacids for gastritis, gastroesophageal reflux disease, or gastric or duodenal ulcers * Intermittent antacid therapy is allowed provided it is given ≥ 6 hours prior to and ≥ 90 minutes after study drug administration