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 corticoster…