Heparin or M-EDTA in Preventing Catheter-Related Infections and Blockages in Patients at High Risk for a Catheter-Related Infection

DISEASE CHARACTERISTICS: * At high risk of acquiring a catheter infection, as evidenced by any of the following: * Diagnosis of leukemia, lymphoma, myeloma, or melanoma-sarcoma * Undergoing hematopoietic stem cell transplantation * Receiving aldesleukin * Pediatric cancer patients * New (≤ 10 days old) functioning externalized tunneled or nontunneled central venous catheter (CVC), such as a Hickman/Broviac or Hohn catheter, or peripherally inserted central venous catheter (PICC) utilized for infusion of chemotherapy, blood and blood products, or other intermittent infusions * No occluded CVC * No existing local or systemic catheter infection * More than 3 days since removal of a prior CVC due to an infection * No externalized CVC that is projected to remain in place for \< 2 weeks * No infusion ports or Groshong catheters * No coated CVC impregnated with an antimicrobial or antiseptic agent PATIENT CHARACTERISTICS: * Life expectancy ≥ 3 months * No history of allergy to any tetracycline * No contraindication to flush solution dwell time of ≥ 4 hours * No hypocalcemia while receiving calcium supplementation through the catheter * Not pregnant or nursing * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: * See Disease Characteristics