Carboplatin With or Without Decitabine in Treating Patients With Progressive, Advanced Ovarian Epithelial Cancer, Fallopian Tube Cancer, or Primary Peritoneal Cancer

RATIONALE: Drugs used in chemotherapy, such as carboplatin and decitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug (combination chemotherapy) may kill more tumor cells. It is not yet known whether carboplatin is more effective with or without decitabine in treating patients with ovarian epithelial cancer, fallopian tube cancer, or primary peritoneal cancer. PURPOSE: This randomized phase II trial is studying carboplatin and decitabine to see how well they work compared with carboplatin alone in treating patients with progressive, advanced ovarian epithelial cancer, fallopian tube cancer, or primary peritoneal cancer.