Neurocognitive impairment in Asian childhood cancer survivors: a systematic review

Childhood cancer survivors are at higher risk of developing neurocognitive deficits due to the intensive treatment they received at an early age. Most studies on childhood cancer survivorship have so far focused on the Western populations. Due to the ethnic, genetic, environmental, and cultural differences, clinical data of the Western populations may not be representative of Asian countries. This scoping review systematically summarized the existing clinical evidence of the neurocognitive impairment of Asian childhood cancer survivors. We searched the Embase and Medline databases for studies assessing the neurocognitive functions of survivors in Asia, who were diagnosed with cancer before the age of 19 and completed active treatment. The literature search identified 13 studies involving 2212 participants from five Asian countries: South Korea (n = 4, 30.8%), Taiwan (n = 3, 23.1%), Japan (n = 3, 23.1%), Hong Kong (n = 2, 15.4%), and Thailand (n = 1, 7.7%). The included studies focused on CNS tumors (n = 10, 76.9%), hematological malignancies (n = 7, 53.8%), or heterogeneous cancer diagnoses (n = 3, 23.1%). Collectively, mild-to-moderate impairment in intelligence was observed in 10.0 to 42.8% of survivors, which seemed higher than the reported rate in Western survivors. We speculate that the ethnic and genetic variations in drug responses and susceptibility to adverse chronic toxicities may have contributed to the differences in the prevalence and severity of neurocognitive impairment between these two populations. To better understand the effects of culturally relevant and region-specific environmental risk factors on the post-treatment neurocognitive development in cancer survivors, a holistic approach that addresses the complex interactions between biological, physical, and psychosocial factors is needed. This will aid the development of effective intervention strategies to improve the functional and psychosocial outcomes of cancer survivors in Asian societies.