PATIENT CHARACTERISTICS: Age: Over 18 Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: No disease exacerbated by light, including systemic lupus erythematosus, psoriasis, porphyria, actinic reticuloid, or xeroderma pigmentosum Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception