Funding: RSF grant No. 25-25-00898 “Psycho-Physiological Indicators of Healthy Siblings’ (Brothers’ and Sisters’) Adaptation in Families of Children With Cancer”.

Acknowledgments: the authors express their gratitude to А.F. Karelin for the opportunity to conduct the study at the Russkoye Pole Treatment and Rehabilitation Research Center (Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology) and А.А. Devyaterikova for the expert opinion about the manuscript.

Author contribution: Likhomanova EN — conceptualization, methodology, research procedure, data processing, manuscript editing; Shevaldova OV — statistical analysis, preparation of illustrations for the article, manuscript writing; Kovaleva AV — project management, administration, manuscript editing.

Compliance with ethical standards: the study was approved by the Ethics Committee of the Anokhin Research Institute of Normal Physiology (protocol No. 18/1 dated February 15, 2023), as well as the Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology (protocol No. 8э/16-17 dated October 27, 2017). The children’s parents submitted the informed consent to take part in the study.