Valganciclovir in Treating Patients With Classic Non-HIV-Associated Kaposi's Sarcoma

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