Although cancer is uncommon is children compared with adults, it is the second commonest cause of death in children. Children with cancer have multiple anesthetics and they report medical procedures or surgery cause the worst pain during their treatment. The issues arising vary during their treatment. Direct effects of tumor give way to systemic effects of treatment, particularly of chemotherapy that can result in potentially life-threatening complications. Pain is often present at the time of diagnosis, but its character may change as pain from procedures and mucositis become predominant. Anterior mediastinal masses, most commonly a lymphoma, compress the structures in the middle mediastinum including the trachea, superior vena cava (SVC) and pulmonary vessels. This group of patients are among the riskiest and most challenging for pediatric anesthetists. Warning signs include supine dyspnea, evidence of significant tracheal compression, and signs of SVC compression. If general anesthesia cannot be avoided, maintenance of chest muscle tone and functional residual capacity are important, and the anesthetic agents ketamine and dexmedetomidine facilitate this.