A Study of Single Agent Pemetrexed Disodium in Treating Patients With Recurrent or Persistent Ovarian or Primary Peritoneal Cancer

Inclusion Criteria: * Histologically confirmed recurrent or persistent disease ovarian epithelial or primary peritoneal cancer * Measurable disease * Must have received 1 prior platinum-based (carboplatin, cisplatin, or another organoplatinum compound) chemotherapy regimen for primary disease. Patients who had not received prior paclitaxel may have received a second regimen that included paclitaxel * Treatment-free interval \< 6 months after prior platinum-based therapy OR progressed during platinum-based therapy * Not eligible for a higher priority Gynecologic Oncology Group (GOG) protocol (i.e., any active phase III GOG protocol for the same patient population) Exclusion Criteria: * Patients who have had prior therapy with pemetrexed * Patients with a history of other invasive malignancies, with the exception of non-melanoma skin cancer, are excluded if there is any evidence of other malignancy being present within the last five years. Patients are also excluded if their previous cancer treatment contraindicates this protocol therapy. * Patients who have received radiation to more than 25% of marrow