OUTLINE: This study seeks to estimate the maximum tolerated dose (MTD) of hydroxyurea in combination with other chemotherapy. Groups of 3 patients take escalated doses of oral hydroxyurea three times weekly or daily throughout treatment with cisplatin plus (per their previous regimen) vinblastine, vindesine, vinorelbine, or etoposide. Treatment continues in responding and stable patients until 3 months beyond documentation of complete remission (minimum 4 courses), maximum of 6 courses beyond documentation of partial remission, or 3 courses beyond documentation of stable disease. Patients are followed every 3 weeks for 3 months, every 6 weeks for 3 months, then every 3 months until disease progression.