Correspondence
Childhood Leukemias
N Engl J Med 1995; 333:1286-1287November 9, 1995
- Article
To the Editor:
The successful treatment of leukemia is one of the great triumphs of modern pediatrics. Twenty-five years ago, a diagnosis of childhood leukemia was a virtual death sentence. Today, as lucidly described by Pui (June 15 issue),1 the majority of children with leukemia are cured.
Unfortunately, the incidence of childhood leukemia has not declined. Instead, the incidence rate for new cases has increased steadily in the United States over the past two decades. For acute lymphoblastic leukemia (ALL), the most common form of leukemia among children, the cumulative increase in the incidence rate from 1973 to 1991 was 20.0 percent.2 This increase is particularly striking among white children. The causes are not known. Possible causes include widespread exposure of children to pesticides, ionizing radiation, dietary nitrites, and electromagnetic fields.3,4 Parental exposure to environmental and occupational toxins has also been implicated.5 Improved diagnostic recognition is not a likely explanation. The review by Pui omits any mention of this increase in the incidence of childhood leukemia and fails to discuss the possible etiologic contribution of environmental exposure.
5 ReferencesPhilip J. Landrigan, M.D.
Mt. Sinai School of Medicine, New York, NY 10029-65741
Pui C-H . Childhood leukemias. N Engl J Med 1995;332:1618-1630
Full Text | Web of Science | Medline2
Ries LAG, Miller BA, Hankey BF, Kosary CL, Harras A, Edwards BK, eds. SEER cancer statistics review, 1973–1991: tables and graphs. Bethesda, Md.: National Cancer Institute, 1994. (NIH publication no. 94-2789.)
3
National Research Council, Committee on Pesticides in the Diets of Infants and Children. Pesticides in the diets of infants and children. Washington, D.C.: National Academy Press, 1993.
4
Feychting M ,Ahlbom A . Magnetic fields and cancer in children residing near Swedish high-voltage power lines. Am J Epidemiol 1993;138:467-481
Web of Science | Medline5
O'Leary LM ,Hicks AM ,Peters JM ,London S . Parental occupational exposures and risk of childhood cancer: a review. Am J Ind Med 1991;20:17-35
CrossRef | Web of Science | Medline
Author/Editor Response
Dr. Pui replies:
To the Editor: I appreciate Dr. Landrigan's reminder that the incidence of childhood ALL has increased while the mortality rate has declined. Although I made this observation early in the review (see “Risk Factors”), I provided little detail because of space constraints.
The data supporting an increased incidence of childhood leukemia come largely from the Surveillance, Epidemiology, and End Results (SEER) Program, which surveys cancer registries covering about 10 percent of the U.S. population.1 These data indicate that during the period from 1973 to 1991, the age-adjusted incidence of childhood ALL increased from 2.7 to 3.3 cases per 100,000 children (from infancy to 14 years of age). With the exception of brain tumors, increases in the incidence of other childhood cancers are less certain because of the relatively small numbers of cases in the analyses.
Clearly, this trend warrants careful investigation to identify probable causes. Though well publicized in recent years, childhood or parental exposure to environmental or occupational hazards has not been conclusively shown to account for the SEER finding. For example, in one report cited by Dr. Landrigan, the risk of leukemia was positively correlated with residential exposure to electromagnetic fields, a calculation based on the distance from power lines, the power-line configuration, and the historical record of power loads. The authors found an inverse correlation, however, when they analyzed spot measurements made directly at the sites of exposure. Similar studies offer little, if any, support for a causative role of this factor in the induction of leukemia.2,3 Although direct or parental consumption of nitrite-cured meats has also been linked to an increased risk of leukemia in children, these studies suffer from limited dietary data, potentially confounding variables, and an apparent bias in the selection of controls.4,5 Finally, surveys of cases of childhood leukemia that developed near nuclear facilities or after paternal irradiation have yielded inconsistent results.5
Many of the deficiencies of past epidemiologic studies of childhood ALL should be eliminated by the large case–control investigations now under way in the United States, as well as the United Kingdom, Germany, and Canada. One hopes that the findings of these important research efforts will yield clues to effective disease prevention.
5 ReferencesChing-Hon Pui, M.D.
St. Jude Children's Research Hospital, Memphis, TN 381051
Ries LAG, Miller BA, Hankey BF, Kosary CL, Harras A, Edwards BK, eds. SEER cancer statistics review, 1973–1991: tables and graphs. Bethesda, Md.: National Cancer Institute, 1994. (NIH publication no. 94-2789.)
2
Olsen JH ,Nielsen A ,Schulgen G . Residence near high voltage facilities and risk of cancer in children. BMJ 1993;307:891-895
CrossRef | Web of Science | Medline3
Verkasalo PK ,Pukkala E ,Hongisto MY , et al. Risk of cancer in Finnish children living close to power lines. BMJ 1993;307:895-899
CrossRef | Web of Science | Medline4
Sarasua S ,Savitz DA . Cured and broiled meat consumption in relation to childhood cancer: Denver, Colorado (United States). Cancer Causes Control 1994;5:141-148
CrossRef | Web of Science | Medline5
Sandler DP . Recent studies in leukemia epidemiology. Curr Opin Oncol 1995;7:12-18
Medline
