DISEASE CHARACTERISTICS:

• Histologically confirmed classic Kaposi's sarcoma (KS) involving the skin

  • Non-HIV-associated disease

    • HIV negative

• Measurable disease

  • At least 8 KS lesions with ≥ 5 marker lesions measurable in 2 dimensions AND ≥ 3 other lesions measuring ≥ 1 cm in diameter

    • Two 3 mm punch biopsies of a non-marker lesion entirely composed of KS
  • Irradiated cutaneous lesions may not be used as indicator lesions
• No known active visceral KS or symptomatic KS-related edema that would preclude function or require cytotoxic chemotherapy

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• Karnofsky 70-100%

Life expectancy

• At least 12 months

Hematopoietic

• Hemoglobin ≥ 8 g/dL
• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3

Hepatic

• Bilirubin ≤ 1.5 times upper limit of normal (ULN)
• AST and ALT ≤ 3 times ULN

Renal

• Creatinine clearance ≥ 50 mL/min

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective barrier contraception during and for 3 months after study participation
• No hypersensitivity to valganciclovir or ganciclovir
• No other neoplasia requiring cytotoxic therapy

PRIOR CONCURRENT THERAPY:

Biologic therapy

• More than 4 weeks since prior biological therapy for KS
• No concurrent immunotherapy

Chemotherapy

• More than 4 weeks since prior chemotherapy for KS
• No concurrent chemotherapy

Endocrine therapy

• No concurrent corticosteroid treatment except for replacement doses (equivalent to 20 mg of hydrocortisone per day)

Radiotherapy

• See Disease Characteristics
• More than 4 weeks since prior radiotherapy for KS
• No concurrent radiotherapy

Surgery

• Not specified

Other

• More than 14 days since prior acute treatment for infection (other than oral thrush or genital herpes) or other serious medical illness
• More than 60 days since prior local therapy for any KS indicator lesion unless the lesion showed documented progression since treatment
• More than 4 weeks since prior local therapy for KS
• More than 4 weeks since prior investigational agents
• More than 4 weeks since other prior antineoplastic therapy for KS
• No other concurrent antiviral therapy
• No other concurrent investigational agents
• No other concurrent systemic therapy for KS