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Research to Identify Late Effects and Their Implications
Most of what has been learned about the late effects of cancer treatment has been the result of longitudinal or cross-sectional studies of survivors treated according to standard protocols within single institutions. These investigations have provided important insights into the frequency and potential risk factors for late effects occurring at relatively high frequency. Such studies have, for example, helped to identify impaired fertility following alkylating agent treatments, hearing impairment following cisplatin-based chemotherapy regimens, and restrictive lung disease following pulmonary radiation. Because these studies were conducted in a single institution, included few subjects, and involved treatment that did not vary markedly across subjects, estimates of risk associated with variations in treatment could usually not be well quantified.
Some studies of long-term survivors have been carried out within established pediatric cooperative groups (e.g., Children’s Cancer Group [CCG], Pediatric Oncology Group [POG], National Wilms Tumor Study Group [NWTSG], Intergroup Rhabdomyosascoma Study Group [IRSG]).1 The primary objective of these groups is to conduct therapeutic clinical trials; and while questions of health-related outcomes are of interest, the resources necessary to support such studies have generally not been available. The potential to conduct research on late effects in these settings is substantial because as many as 50 to 60 percent of U.S. children with cancer are treated at Children’s Oncology Group (COG) member institutions (Shochat et al., 2001). A Late Effects Committee established in the mid 1980s promotes and facilitates research on adverse health-related outcomes after childhood cancer (Bhatia, 2002). Research efforts in this area have, however, been limited (Box 8.1). Some of the early findings on cognitive late effects among children with leukemia emerged from follow-up studies of children enrolled in clinical trials of the Cancer and Leukemia Group B Cooperative Group (CALGB). Investigators of the National Wilms’ Tumor Study Group (NWTSG) were instrumental in recognizing the late effects of therapies among survivors of Wilms’ tumor and adjusting treatment (e.g., omission of radiotherapy) in an effort to avoid these late side effects.
COG has plans for a long- term follow-up center to provide a cost-effective mechanism for tracking and maintaining contact with patients and their families and for collecting long-term data on health and health-related quality of life. This system complements a web-based remote data entry
The National Cancer Institute-sponsored pediatric cooperative groups, now merged into the Children’s Oncology Group, are also discussed in Chapter 5.