odern therapy for childhood cancer began about 1970, and by the middle of that decade many children who had discontinued treatment continued to remain in remission. Clinical trials have confirmed that there are large numbers of youngsters and young adults who are cured and who have many years of productive life ahead of them. At the same time, concern regarding the prospects for the continuing health of these survivors began to be expressed, and a growing body of knowledge revealed a wide range of outcomes: although many survivors are leading normal lives with no apparent disability, some have been left with long-term sequelae, ranging from mild cosmetic changes to lifethreatening cardiac and renal disease. Other studies of health-related outcomes began to link specific aspects of therapy to certain undesirable consequences.
The past 20 years have witnessed further improvements in cure rates; it is now believed that three of every four children treated for cancer will be long-term survivors. The psychological consequences of having survived a life-threatening illness also began to emerge as a significant late effect, with much new descriptive, analytic, and intervention research taking place. Knowledge concerning late complications has led to clinical trials that test the effectiveness of treatment modifications designed to reduce or eliminate these complications and to recommendations for surveillance and follow-up of survivors. Questions have also been raised concerning the optimal method of gathering nonbiased data regarding the health and quality of life of long-term survivors. Numerous practical and ethical issues have impacted research methodology in light of the reluctance of many subjects to return for ongoing care. Absence of adequate medical coverage for follow-up studies can lead to problems in providing necessary clinical care and in assuring that bias does not influence research results.
Outcomes research in survivors of childhood cancer was conducted initially by interested investigators at single institutions. Then, because of