The therapeutic outcomes of microscopically identical cancers in adults and children are often different. Childhood ALL has a 5-year survival rate of about 83 percent. In adults under age 65, the “same” leukemia has a much lower 5-year survival rate, from 20 to 30 percent (Ries et al., 2002). Better outcomes among children relative to adults are likely due to significant differences in the molecular, cytogenetic, and immunologic features of ALL in adults and children. For example, the Philadelphia chromosome, a cytogenetic feature associated with a very low survival, is present in 30 to 40 percent of adults, but less than 5 percent of children (Look and Kirsch, 2002).
The fact that childhood cancer occurs in the context of rapid and dramatic growth and development also distinguishes it from adult cancers.
Childhood cancer is rare, but with improvements in treatment there has been a dramatic growth in the population of survivors. In 1997, there were an estimated 270,000 survivors of childhood cancer; 95,000 of them were under age 20 and the balance were adults. This translates to about 1 in 810 individuals under age 20 having a history of cancer, and 1 in 640 adults ages 20 to 39 having such a history.
Childhood cancers are a diverse set of conditions, but three predominant types make up the majority of diagnosed cases: leukemia; CNS and brain tumors; and lymphomas. Five-year survival rates vary by type of childhood cancer, but overall, 78 percent of children diagnosed with cancer will be alive in 5 years. Gains in survival have occurred for most types of childhood cancer, but the greatest strides have been made in children treated for leukemia. Even though mortality rates have declined steadily since 1975, cancer remains a leading cause of death among children.
American Cancer Society. 2000. Cancer Facts and Figures, 2000. Atlanta, GA: American Cancer Society.
Bhatia S, Sather HN, Heerema NA, Trigg ME, Gaynon PS, Robison LL. 2002. Racial and ethnic differences in survival of children with acute lymphoblastic leukemia. Blood 100(6):1957-64.
Look A. T., Kirsch I.R. 2002. Molecular Basis of Childhood Cancer. Pizzo PA, Poplack DG In: Principles and Practice of Pediatric Oncology. Fourth ed. Philadelphia: Lippincott Williams & Wilkins. Pp. 45-88.
Minino AM, Smith BL. 2001. Deaths: preliminary data for 2000. Natl Vital Stat Rep 49(12):1-40.
Pui CH, Boyett JM, Hancock ML, Pratt CB, Meyer WH, Crist WM. 1995. Outcome of treatment for childhood cancer in black as compared with white children. The St Jude Children’s Research Hospital experience, 1962 through 1992. JAMA 273(8):633-7.