Pemetrexed Disodium in Treating Patients With Recurrent or Persistent Low-Risk Gestational Trophoblastic Tumor After a Molar Pregnancy

DISEASE CHARACTERISTICS: Diagnosis of low-risk post-molar gestational trophoblastic tumor, defined as 1 of the following: Increasing human chorionic gonadotropin (hCG) levels on ≥ 3 consecutive measurements taken over ≥ a 2-week period Less than 10% decrease of hCG levels on 4 measurements taken over ≥ a 3-week period Persistent or recurrent disease Histologically confirmed complete or partial mole on initial evacuation Prior pregnancy ≤ 12 months ago No histologically confirmed choriocarcinoma or placental site trophoblastic tumor on initial evacuation Failed only 1 prior dactinomycin or methotrexate therapy (with or without leucovorin calcium) WHO score 2-6 No evidence of metastatic disease, except to the lung or vagina, on physical exam, chemistry, chest X-ray, and ultrasound No liver, spleen, brain, kidney, or gastrointestinal tract metastases No more than 8 metastatic lesions PATIENT CHARACTERISTICS: Age Any age Performance status GOG 0-1 Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Granulocyte count ≥ 1,500/mm^3 Hepatic Bilirubin ≤ 1.5 times upper limit of normal (ULN) SGOT ≤ 3 times ULN Alkaline phosphatase ≤ 3 times ULN Renal Creatinine ≤ 1.5 mg/dL Creatinine clearance ≥ 45 mL/min Other Not pregnant or nursing Fertile patients must use effective contraception during and for 3 months after study participation No significant infection No other invasive malignancy within the past 5 years except nonmelanoma skin cancer PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent prophylactic filgrastim (G-CSF) unless for recurrent neutropenic complications No concurrent prophylactic thrombopoietic agents unless for recurrent grade 4 thrombocytopenia Chemotherapy See Disease Characteristics At least 7 days since prior dactinomycin or methotrexate (with or without leucovorin calcium) and recovered No prior pemetrexed disodium No other prior chemotherapy Endocrine therapy Not specified Radiotherapy At least 14 days since prior radiotherapy and recovered No prior radiotherapy to ≥ 25% of the bone marrow Surgery Recovered from prior surgery Other No nonsteroidal anti-inflammatory drugs or salicylates for 2 days (or 5 days for drugs with a long half-life) before, during, and for 2 days after pemetrexed disodium administration Concurrent low-dose aspirin (≤ 325 mg/day) allowed