Over the past several decades, the prognosis for childhood cancer has improved such that 60% to 70% of children are cured. The need for recognition and treatment of complications arising in children with cancer comes with these advances. Some of these complications are true emergencies. Attention must be directed toward those problems that threaten vital organs or compromise the long-term quality of life. Before definitive therapy for the malignancy can begin, the primary care physician may have to stabilize the child. Once the emergency has been identified, transfer should be arranged to a center with experience in treating children with cancer. The advances we have made in the management of children with cancer have emerged from the expertise available at such major treatment centers.

The purpose of this article is to enable the physician to recognize common emergencies arising that are the first signs of cancer in a previously well child and those occurring from treatment or at the time of tumor recurrence. Table 1, Table 2, and Table 3 list these emergencies according to their pathogenesis: emergencies caused by space-occupying lesions, emergencies caused by abnormalities of blood and blood vessels, and metabolic emergencies. Some emergencies demand immediate attention; others are potentially life-threatening. This distinction is as follows: