The SCCSS is designed to investigate which long-term effects childhood cancer and its treatment have on survivors, and includes those who were under 20 years when they were diagnosed. The SCCSS explores childhood cancer survivors' quality of life, the health care received by childhood cancer survivors during follow-up care, the effects of medication, somatic and psychosocial health issues, how childhood cancer survivors take care of their own health including health behaviors, and also collects demographic details like family background, education and profession. To learn more about these topics, the investigators send questionnaires to childhood or adolescent cancer survivors. The investigators use the results to inform physicians and patients, and to improve treatment of childhood cancer and follow-up.

The SCCSS is designed to investigate which long-term effects childhood cancer and its treatment have on survivors, and includes those who were under 20 years when they were diagnosed. The SCCSS explores childhood cancer survivors' quality of life, the health care received by childhood cancer survivors during follow-up care, the effects of medication, somatic and psychosocial health issues, how childhood cancer survivors take care of their own health including health behaviors, and also collects demographic details like family background, education and profession. To learn more about these topics, the investigators send questionnaires to childhood or adolescent cancer survivors. The investigators use the results to inform physicians and patients, and to improve treatment of childhood cancer and follow-up.

Background: Therapies have improved so much in the past decades that more than 80% of children and adolescents now survive cancer. This means that the population of long-term childhood cancer survivors is growing. Since cancer and its treatments may later have adverse effects, it is important to track and improve survivor health and quality of life. Comprehensive data on the burden of late effects of childhood cancer or risk factors for late effects was not available, and so Switzerland set up the SCCSS to increase knowledge and improve the quality of care and follow-up.

Objectives: The SCCSS investigates long-term outcomes of survivors of childhood and adolescent cancer, and the incidence and spectrum of various somatic and psychosocial outcomes including late mortality, second primary malignancies, somatic health and medication, mental health, educational achievements, health-related quality of life, and the association of these outcomes with risk factors like tumor, treatment modalities, and demographic characteristics. The SCCSS also investigates how health-care is provided, and how long-term childhood cancer survivors take care of their health inducing health behaviors.

Methods: All Swiss residents who were diagnosed with cancer at age <20 years, have survived at least 5 years since cancer diagnosis, received a detailed questionnaire. The investigators added data from general practitioners and hospital records. To compare survivors with the general population, they also send the questionnaire to the siblings of childhood cancer survivors. Since 2025 we ask participants of the SCCSS if they are interested in wearing an accelerometer for one week to track the amount of time they spend moving, sitting and sleeping (SCCSS-Activity).

Rationale and significance: The data collected by the SCCSS allows the investigators to study long-term outcomes of Swiss childhood cancer survivors. The SCCSS helps to learn more about the incidence of late effects and their risk factors. It also allows to summarize the current state of care in Switzerland. Since early diagnosis can prevent or mitigate many late effects, tracking them will help to improve the health of current and future childhood cancer survivors.

Current status of the SCCSS: From 2008-2026, the investigators have contacted 7867 childhood cancer survivors diagnosed between 1976-2019 and 2074 of their siblings. The investigators contact new 5-year childhood cancer survivors at regular intervals, and continuously analyse and publish data and findings. By 2022, the investigators have contacted 3443 childhood cancer survivors for a follow-up questionnaire and will continue with this at regular intervals.

Current status of the SCCSS-Activity: From 2025, the investigators have asked 369 participants of the SCCSS if they are interested in participating in the SCCSS-Activity.

Funding: Swiss Cancer League/ Swiss Cancer Research (Grant No: KLS/KFS-4825-01-2019), Stiftung für krebskranke Kinder (Regio basiliensis) and Kinderkrebshilfe Schweiz.

Inclusion Criteria:

• Who were diagnosed with cancer at age <20 years
• Who have survived at least 5 years after cancer diagnosis
• Who were Swiss residents when they were diagnosed, and
• Who gave informed consent

Childhood cancer survivors: All living individuals who were diagnosed with cancer at age <20 years, have survived at least 5 years after cancer diagnosis, and who were Swiss residents when they were diagnosed.

Siblings: brothers and sisters of childhood cancer survivors.