Gemcitabine and Topotecan in Treating Patients With Recurrent or Persistent Ovarian, Fallopian Tube, or Primary Peritoneal Cavity Cancer

DISEASE CHARACTERISTICS: Diagnosis of ovarian, fallopian tube, or primary peritoneal cavity cancer Recurrent or persistent platinum-refractory disease, as defined by 1 of the following: Progressive disease while on a platinum compound Persistent clinically measurable disease with best response as stable disease at the completion of ≥ 6 courses of therapy Recurrent disease within 6 months after completion of therapy Measurable or evaluable disease Evaluable disease, defined as CA 125 ≥ 100 U/mL (confirmed by 2 blood tests) Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques, including palpation, plain x-ray, CT scan, or MRI, OR ≥ 10 mm by spiral CT scan PATIENT CHARACTERISTICS: Age 18 and over Performance status GOG 0-3 Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Bilirubin ≤ 1.5 times upper limit of normal (ULN) SGOT ≤ 2.5 times ULN Alkaline phosphatase ≤ 2.5 times ULN Renal Creatinine ≤ 1.5 times ULN Creatinine clearance > 50 mL/min Other No clinically significant infection No other severe medical condition that would preclude study treatment No other malignancy within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix or breast PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy See Disease Characteristics Prior gemcitabine or topotecan allowed provided disease is not refractory to either drug At least 3 weeks since prior chemotherapy and recovered Endocrine therapy Not specified Radiotherapy At least 3 weeks since prior radiotherapy and recovered Surgery Recovered from recent prior surgery