DISEASE CHARACTERISTICS:

• Have undergone allogeneic peripheral blood stem cell, cord blood, or marrow transplantation (related or unrelated, T-cell depleted or non-T-cell depleted, CD34-selected or non-selected, or myeloablative or non-myeloablative) within the past 80-120 days

• Positive pre-transplantation cytomegalovirus (CMV) serology of recipient and/or donor

  • Seropositive recipients with one of the following:

    • CMV infection before day 80, as determined by:

      • pp65 antigenemia
      • CMV DNA in plasma
      • Peripheral blood leukocytes (PBL) or whole blood at any level detected by polymerase chain reaction or hybrid capture
      • CMV pp67 mRNA
      • CMV viremia by blood culture
      • Surveillance bronchoalveolar lavage (culture or cytology)
    • CMV disease more than 6 weeks prior to enrollment

    • Presence of graft-versus-host disease (GVHD) at enrollment

      • Acute GVHD that requires treatment with systemic corticosteroids of doses greater than 0.5 mg/kg OR
      • Chronic clinically extensive GVHD requiring treatment with corticosteroids
    • Continuous prophylaxis with ganciclovir, foscarnet, or cidofovir between engraftment and day 80 OR
  • Seronegative recipient with seropositive donor who has CMV infection before day 80
• No rising or uncontrolled CMV load (pp65 antigenemia levels no greater than 1/slide or no greater than 100 copies of CMV DNA per mL of plasma or per million PBL allowed)
• No CMV disease within 6 weeks prior to randomization

• No leukemic relapse

  • Cytogenetic or molecular relapse allowed

PATIENT CHARACTERISTICS:

Age:

• 16 and over

Performance status:

• Not specified

Life expectancy:

• At least 2 weeks

Hematopoietic:

• Absolute neutrophil count at least 1,000/mm^3 for at least 1 week prior to enrollment

Hepatic:

• Not specified

Renal:

• Creatinine no greater than 2.5 mg/mL

Other:

• No hypersensitivity to ganciclovir or valganciclovir
• No uncontrolled diarrhea or severe gastrointestinal disease that would preclude oral medication
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 90 days after study participation
• HIV negative
• Proficient in English

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• See Disease Characteristics

Chemotherapy:

• Not specified

Endocrine therapy:

• See Disease Characteristics

Radiotherapy:

• Not specified

Surgery:

• Not specified

Other:

• Prior ganciclovir, foscarnet, cidofovir, high-dose acyclovir, or valacyclovir as prophylaxis or preemptive therapy allowed
• No concurrent prophylactic foscarnet, cidofovir, or ganciclovir (IV or oral)

• No concurrent prophylactic high-dose acyclovir (more than 800 mg twice daily), valacyclovir (more than 500 mg twice daily), cidofovir (more than 0.5 mg/kg per week), or famciclovir (more than 500 mg/day) except for limited treatment courses at higher doses for varicella-zoster virus infections

  • Concurrent low-dose (≤ 0.5 mg/kg per week) cidofovir allowed for limited treatment courses