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Background: Childhood cancer survivors are at risk for developing long-term adverse health outcomes. To identify the risk of and risk factors for specific health outcomes, well-established cohorts are needed with detailed information on childhood cancer diagnosis, treatment, and health outcomes. We describe the design, methodology, characteristics, and data availability of the Dutch Childhood Cancer Survivor Study LATER cohort (1963-2001 part 1; questionnaire and linkage studies. Methods: The LATER cohort includes 5-year childhood cancer survivors, diagnosed in the period 1963-2001, and before the age of 18 in any of the seven former pediatric oncology centers in the Netherlands. Information on health outcomes from survivors and invited siblings of survivors was collected by questionnaires and linkages to medical registries. Results: In total, 6165 survivors were included in the LATER cohort. Extensive data on diagnosis and treatment have been collected. Information on a variety of health outcomes has been ascertained by the LATER questionnaire study and linkages with several registries for subsequent tumors, health care use, and hospitalizations. Conclusion: Research with data of the LATER cohort will provide new insights into risks of and risk factors for long-term health outcomes. This can enhance risk stratification for childhood cancer survivors and inform surveillance guidelines and development of interventions to prevent (the impact of) long-term adverse health outcomes. The data collected will be a solid baseline foundation for future follow-up studies.

This review aimed to assess participation rates of childhood cancer survivors (CCS) invited to fill out a health-related questionnaire. Additionally, effects of study and CCS characteristics on participation rates were examined. PubMed, Web of Science, Ovid (EMBASE) and CINAHL databases were searched. Publications included were questionnaire-based studies among CCS diagnosed with cancer before the age of 21, alive at least 5 years past diagnosis and aged 16 years or older at the time of study. Thirty-five studies were included; the median participation rate was 65%. Sixteen studies reported information about CCS actively declining participation (median rate 5%). Five study characteristics seemed to influence participation rates: the use of reminders and incentives, the option to answer a shortened questionnaire, the recruitment of participants through their general practitioner and a pre-notification before sending out the questionnaire. Furthermore, CCS characteristics related to improved participation were female gender, Caucasian ethnicity and a higher educational level. The results of this study will help to improve the (methodological) quality of future questionnaire-based studies among CCS, thereby increasing our knowledge about late effects among this group of survivors.