This phase II trial is studying how well lenalidomide works in treating older patients with acute myeloid leukemia with abnormal chromosome 5q. Biological therapies, such as lenalidomide, may stimulate the immune system in different ways and stop cancer cells from growing.

PRIMARY OBJECTIVES: I. Test whether the complete response rate among older patients with previously untreated acute myeloid leukemia (AML) with the del (5q) cytogenetic abnormality treated with lenalidomide is sufficiently high to warrant a phase III investigation. II. Estimate the frequency and severity of toxicities of this drug in these patients. III. Correlate, in a preliminary manner, additional cytogenetic abnormalities with response to lenalidomide. IV. Estimate the total (complete and partial) response rate and the cytogenetic response rate in these patients. OUTLINE: INDUCTION THERAPY: Patients receive oral lenalidomide once daily on days 1-14, 1-21, or 1-28 (course 1). Patients undergo bone marrow biopsy on day 28 or 35 to assess treatment efficacy. Patients with stable or improving disease (i.e., a decrease in blast percentage) without progressive disease proceed to maintenance therapy. MAINTENANCE THERAPY: Beginning within 42 days after completion of induction therapy, patients receive oral lenalidomide once daily on days 1-21. Courses repeat every 28 days in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed periodically for up to 5 years.