Pain in long-term survivors of childhood cancer: A systematic review of the current state of knowledge and a call to action from the Children's Oncology Group.

Survivors of childhood cancer may be at risk of experiencing pain, and a systematic review would advance our understanding of pain in this population. The objective of this study was to describe: 1) the prevalence of pain in survivors of childhood cancer, 2) methods of pain measurement, 3) associations between pain and biopsychosocial factors, and 4) recommendations for future research. Data sources for the study were articles published from January 1990 to August 2019 identified in the PubMed, PsycINFO, EMBASE, and Web of Science data bases. Eligible studies included: 1) original research, 2) quantitative assessments of pain, 3) articles published in English, 4) cancers diagnosed between birth and age 21 years, 5) survivors at 5 years from diagnosis and/or at 2 years after therapy completion, and 6) a sample size >20. Seventy-three articles were included in the final review. Risk of bias was considered using the Cochrane risk of bias tool. The quality of evidence was evaluated according to Grading of Recommendations Assessment Development and Evaluation (GRADE) criteria. Common measures of pain were items created by the authors for the purpose of the study (45.2%) or health-related quality-of-life/health status questionnaires (42.5%). Pain was present in from 4.3% to 75% of survivors across studies. Three studies investigated chronic pain according the definition in the International Classification of Diseases. The findings indicated that survivors of childhood cancer are at higher risk of experiencing pain compared with controls. Fatigue was consistently associated with pain, females reported more pain than males, and other factors related to pain will require stronger evidence. Theoretically grounded, multidimensional measurements of pain are absent from the literature.