Long-term cancer risk in historic cohorts of patients with adolescent idiopathic scoliosis: a systematic review

Purpose: To evaluate the long-term cancer risks associated with AIS, focusing on the roles of genetic predispositions and radiation exposure. Methods: A comprehensive systematic search was conducted on August 5, 2024, across PubMed, EMBASE, Scopus, Cochrane Libraries, and CINAHL, covering studies from 1947 onward. Human studies on patients with scoliosis diagnosed before age 20 were included. For cancer assessment, both risk, incidence and mortality were included. Studies were excluded if they focused solely on congenital or secondary scoliosis. Screening and quality assessment were conducted using Covidence. The first author performed the initial screening, while the first and second authors conducted full-text assessments and quality assessment collaboratively, with an agreement score of 0.83. Results: Seven studies from the USA, Australia, Denmark and The Netherlands were identified. Notable findings included elevated breast cancer risks among US cohorts, linked to historical radiographic practices that delivered higher radiation doses. None of the included studies assessed genetic etiologies of cancer. Risk of bias in the studies were generally attributed to selection bias and underreporting of characteristics and confounding variables. While most studies included either showed a tendency or a significant association towards an association between scoliosis and risk of cancer, it was mainly based on data before 1990 with exposure to radiation several orders of magnitude larger than modern standards. These changes could be a major factor in the risk of cancer identified in historical cohorts. Conclusion: This review highlights the importance of continued research, including the effect of modern examination techniques, such as EOS, MRI on rates of cancer in modern populations.