Eastern Cooperative Oncology Group randomized trials of observation versus maintenance therapy for patients with metastatic breast cancer in complete remission following induction treatment. - Falkson G; Gelman RS; Pandya KJ; Osborne CK; Tormey D; Cummings FJ; Sledge GW; Abeloff MD (Journal of clinical oncology : official journal of the American Society of Clinical Oncology, 1998)