Network Activeoncokids - Centralized Physical Activity Counseling for Children, adolescents, and Young Adults Across German-Speaking Countries Throughout All Oncological Treatment Phases.

Reaching age-appropriate physical activity levels is a significant challenge for many children, adolescents, and young adults (CAYAs) with and following an oncological disease. Many CAYAs require support in addressing physical activity-specific questions and need assistance in accessing sports and exercise offers in their local area. Since many clinics cannot provide such time-intensive counseling, the nationwide operating network ActiveOncoKids (NAOK), funded by the German Cancer Aid, offers individualized support to participate in physical activity (PA). This paper describes the NAOK-Physical-Activity-Counseling (-PAC) concept and evaluates the initial 200 consultations, focusing on recruitment, objectives, and oncology-specific parameters. Ultimately, dimensions of barriers and facilitators and intervention options are discussed.

Physical activity behaviors and screen time in young childhood cancer survivors: the Physical Activity in Childhood Cancer Survivors Study.

PURPOSE: In childhood cancer survivors (CCS), high physical activity (PA) and low sedentary time may reduce risks of late-effects. PA behaviors and screen time, and how they relate to moderate-to-vigorous PA (MVPA) in CCS, are largely unknown. We examined PA behaviors and screen time, and their cross-sectional associations with MVPA. METHODS: CCS from any cancer diagnosis (≥ l year post-treatment), aged 9-16 years at study, were eligible in the international Physical Activity in Childhood Cancer Survivors (PACCS) study. PA behaviors (school transport, intensity-effort in physical education ("PE intensity"), leisure-time PA) and screen time were assessed by self-report, and MVPA by accelerometers (ActiGraph GT3X-BT). Multivariable linear regressions were used to assess associations between PA behaviors and screen time with MVPA. RESULTS: We included 481 CCS (48% girls, mean age 12.2 years). Passive school transport (prevalence 42%) was associated with 10% lower MVPA/day (ß = 6.6 min, 95% CI 3.3-10.0), low PE intensity (prevalence 21%) with 16% lower MVPA/day (ß = 10.2 min, 95% CI 6.0-14.3), and low leisure-time PA (prevalence 34%) with 15% lower MVPA/day (ß = 9.4 min, 95% CI 1.0-17.7), compared to active school transport, high PE intensity and high leisure-time PA, respectively. High screen time was not associated with MVPA. CONCLUSION: Interventions aiming to increase PA behaviors rather than reducing screen time may be more efficient in promoting a healthy lifestyle in CCS through increased MVPA. Encouraging active transport, high PE intensity, and high leisure-time PA seems important in survivorship care. IMPLICATIONS FOR CANCER SURVIVORS: Young CCS may benefit from engaging in active transport, high PE intensity, and high leisure-time PA.

Severely reduced physical performance is already present at the time of admission for stem cell transplantation.

Objectives: Paediatric patients with cancer undergoing allogeneic haematopoietic stem cell transplantation (allo-HSCT) face a high risk for life-threatening infections and transplant-related complications. Therefore, these children should be in the best possible physical condition beforehand. The study aims to evaluate the fitness status before allo-HSCT and identify correlations between fitness, quality of life and fatigue, clinical data, and previous exercise sessions. Methods: Paediatric patients with cancer ≥4 years old, treated with allo-HSCT, were recruited for the ANIMAL trial ("Effects of a low vs. moderate intense exercise program on immune recovery during paediatric allo-HSCT.", DRKS ID:DRKS00019865). Assessed at admission for HSCT were (1) clinical and anthropometric data, (2) motor performance (strength, endurance and balance) and (3) psychological parameters. Values were compared with published reference values (normative data from the literature) of healthy children, and correlation analyses were conducted. Results: 22 paediatric patients undergoing pre-allo-HSCT (23% female, 9.4±4.5 years, 73% leukaemia) exhibited substantial reduced differences in all motor performance parameters, with up to -106%±98 (mean difference to reference value) in static stance, -37%±45 in sit-to-stand, -52%±16 in leg extension and -48%±22 in hand grip strength compared with reference values. Correlations were observed among age and fitness parameters, the number of inpatient days and fatigue, and many previous exercise sessions correlated with better hand grip strength. Conclusion: These results indicate a poorer fitness status in children before HSCT compared with healthy children, recommending the need for structured exercise programmes for children undergoing HSCT. Differently directed correlations between age/body mass index and endurance/strength and between exercise sessions and strength show the importance of individualised training recommendations and the effect of training.

P-move: a randomized control trial of exercise in patients with advanced pancreatic or biliary tract cancer (aPBC) receiving beyond first-line chemotherapy.

PURPOSE: Patients with advanced pancreatic and biliary tract cancer (aPBC) frequently suffer from high symptom burden. Exercise can reduce treatment side effects and improve patient-related outcomes (PROMs). However, evidence from prospective studies regarding feasibility and efficacy in advanced settings are sparse. The primary aim of this prospective, randomized-controlled study was to evaluate the feasibility and effects of exercise (ET) in patients with aPBC. METHODS: Patients with aPBC beyond first-line therapy were randomized according to the minimization procedure with stratification by gender, age, and loss of body weight in the past six months. The intervention group (IG) completed 3 training units/week for 8 weeks (1x supervised strength sessions, 2x individualized home-based sessions). Control group (CG) received recommendations on physical activity during cancer. RESULTS: 41 patients (stage IV pancreatic or biliary tract cancer) were included no adverse events related to exercise occurred during the trial. Physical function increased significantly in IG in 5 out of 7 physical domains. Comparison of IG and CG at 8 weeks (t2) showed significant differences in favour of IG in leg press (p=0.001), bench press (p=0.011), sit-to-stand (p=0.001) and crunch (0.006). Constipation revealed a significant difference in favour of IG at t2 (p=0.033). Quality of life stabilized/increased in IG during the study period compared to a decrease in CG. Throughout/Over the 8 weeks, fatigue notably reduced in the IG (p=0.028). CONCLUSION: Exercise is safe and feasible in patients with aPBC undergoing further line therapy. Significant improvements in physical functioning and increased quality of life were achieved. German Clinical Trials Register ID: DRKS00021179; Registration date 15.05.2020.

Availability and adaption of exercise programs in pediatric oncology during the COVID-19 pandemic and beyond: a nationwide follow-up survey of providers in Germany.

Background: The COVID-19 pandemic has presented major challenges to clinical practice and delivery of care programs throughout all health care systems. Exercise programs, that are implemented in most centers for pediatric oncology in Germany, are a relatively new care program however with high clinical impact and health benefits. Objective: The impact and consequences of the pandemic on the delivery and availability of exercise programs in Germany for pediatric cancer patients and survivors are unknown. A national survey analyzed restrictions, challenges and novel approaches of exercise program delivery and scientific research. Method: A two-stage online survey was distributed to providers of exercise programs (acute clinics, non-clinical institutions, rehabilitation facilities) via the established Network ActiveOncoKids. Data was collected during the pandemic in 2022 and 2023 using a combination of open and closed questions. Results: In total, n = 27 (response rate: 82%) and n = 17 (response rate: 63%) providers participated in the first and second survey, respectively. Findings pointed out restrictions in 85% of all exercise programs in 2020 and 2021, with slight reductions in 2022. During pandemic, restrictions with major impact arose within exercise offers during follow-up and declined gradually. Whereas restrictions within the setting of acute therapy had medium or minor impact but persisted beyond. Delivery of provided exercise programs necessitated adaptions, including digital methods, supervised interventions from a distance and change of locations. Discussion: The findings highlight the adaptability, the demand and the potential of exercise programs in pediatric oncology. We assume that exercise professionals have used the pandemic-related challenges to review and modify existing concepts and made adaptations according to local conditions and novel tools for the provision of exercise programs. Nevertheless, a conspicuous lack of exercise-related care has become evident in certain patients and survivors. Further expansion of programs is imperative to address and accommodate all pertinent needs.

Exercise Therapy in Oncology.

BACKGROUND: The diagnosis and treatment of cancer are highly stressful. Exercise therapy is often used to mitigate the adverse effects of treatment. But how good is the evidence base, and what has changed in recent years? In this narrative review, we present the current data and what it implies for the care of adults with cancer. METHODS: This review is based on data from meta-analyses and systematic reviews concerning 16 relevant clinical endpoints (outcomes) of exercise therapy for cancer patients. RESULTS: The literature evaluated for this paper reveals that targeted exercise therapy is feasible and safe under appropriate supervision. It is highly effective for improving eight endpoints (anxiety, depression, fatigue, quality of life, physical function, secondary lymphedema after breast cancer, urinary incontinence, post-mastectomy pain syndrome in breast cancer) and may also have a beneficial effect on sleep quality, cardiotoxicity, and cognitive function. Less conclusive studies are currently available with respect to chemotherapy-induced polyneuropathy, nausea/vomiting, and bone health. There is currently insufficient data to suggest any benefit with respect to sexual function and risk factors for falling. CONCLUSION: The data shows that exercise therapy for cancer patients is safe and has manifold effects on selected clinically relevant parameters. Further studies should be performed regarding the possible utility of exercise therapy against treatment-related side effects for which the evidence is currently insufficient. On the basis of the currently available and already existing recommendations, quality-assured exercise therapy can be recommended to cancer patients suffering from a wide range of neoplastic conditions.

Factors That Influence Physical Activity Behavior in Children and Adolescents During and After Cancer Treatment: A Qualitative Systematic Review of the Literature.

PURPOSE: The aim of this systematic review is to reveal the social, personal, and contextual factors that influence physical activity (PA) in children and adolescents during and after cancer treatment. METHOD: SPORTDiscus, Cochrane, Web of Science, PubMed, and FIS Education electronic database were systematically searched. RESULTS: The 13 included studies show that social support (parents, siblings, and friends) in particular is rated as important by cancer survivors; for example, doing PA together. Depending on the treatment status and state of health, particularities arise. During the acute treatment phase, parents issued more prohibitions regarding PA than after treatment. The state of health and concern about infections are described as inhibiting factors. Not all hospitals generally offer special exercise programs for cancer patients, and in some cases, only sporadic exercise sessions were conducted by specialized staff. In addition, the hospital atmosphere, such as cramped rooms, tends to be associated with demotivating effects. CONCLUSIONS: Both inhibiting and promoting factors in the area of social, personal, and contextual factors could be identified. The most fundamental factor for PA is the physical condition. Social factors, such as parents or friends, often have a motivating effect and can promote PA. Inhibiting factors are mainly context-related, such as an environment unsuitable for PA. Although the review highlights interesting aspects, further treatment-related and longitudinal studies could provide deeper insights.

Physical Activity Among Adolescent Cancer Survivors: The PACCS Study.

OBJECTIVES: Physical activity (PA) may modify risks of late effects after cancer. We aimed to examine levels of PA and sedentary time (ST) in a large, international sample of adolescent childhood cancer survivors in relation to sociodemographic and cancer-related factors and compare levels of PA and ST to reference cohorts. METHODS: Survivors from any cancer diagnosis who had completed cancer treatment ≥1 year ago, aged 9 to 16 years, were eligible for the multicenter Physical Activity in Childhood Cancer Survivors study. PA and ST were measured by ActiGraph GT3X+ accelerometers. We performed linear regression analyses to assess factors associated with moderate-to-vigorous PA (MVPA) and ST, and compared marginal means of total PA, MVPA, and ST in 432 survivors to sex- and age-stratified references (2-year intervals) using immediate t-tests for aggregated data. RESULTS: Among survivors, 34% fulfilled the World Health Organization's PA recommendation of ≥60 min of daily MVPA on average and their ST was 8.7 hours per day. Being female, older, overweight, a survivor of central nervous system tumor, or having experienced relapse were associated with lower MVPA and/or higher ST. Generally, male survivors spent less time in MVPA compared with references, whereas female survivors had similar levels. Both male and female survivors had higher ST than references in nearly all age groups. CONCLUSIONS: The low PA and high ST in this large sample of adolescent childhood cancer survivors is worrisome. Combined, our results call for targeted interventions addressing both PA and ST in follow-up care after childhood cancer.

Guideline for the management of fatigue in children and adolescents with cancer or pediatric hematopoietic cell transplant recipients: 2023 update.

Objective was to update a clinical practice guideline (CPG) for the management of fatigue in children and adolescents with cancer or pediatric hematopoietic cell transplant recipients. We reconvened a multi-disciplinary and multi-national panel. While the previous 2018 CPG evaluated adult and pediatric randomized controlled trials (RCTs) to manage fatigue, this 2023 update revised previous recommendations based only on pediatric RCTs. Twenty RCTs were included in the updated systematic review. Physical activity significantly reduced fatigue (standardized mean difference -0.44, 95% confidence interval -0.64 to -0.24; n = 8 RCTs). Using the 2018 recommendations as a basis, the panel continued to make strong recommendations to use physical activity, and to offer relaxation, mindfulness or both, to manage fatigue in pediatric patients. Cognitive or cognitive behavioral therapies may be offered. Pharmacological approaches should not be routinely used. The panel made a new good practice statement to routinely assess for fatigue, ideally using a validated scale.

First Pediatric Exercise Oncology Congress (PEOC).

On behalf of the 1st Pediatric Exercise Oncology Congress, we are pleased to present the abstracts from the 2022 Conference, the inaugural gathering of an international congress. The conference was held virtually on 7 and 8 April 2022. This conference brought together key stakeholders in pediatric exercise oncology, including multidisciplinary professionals from exercise, rehabilitation medicine, psychology, nursing, and medicine. The participants included clinicians, researchers, and community-based organizations. Twenty-four abstracts were selected for presentations (10-15-min oral presentations). In addition, there were five invited speakers with 20 min presentations and two keynotes with 45 min presentations. We congratulate all the presenters on their research work and contribution.

Exercise Preferences in Young Adults with Cancer-The YOUEX Study.

(1) Background: Strong evidence supports the persuasive positive effects of exercise for cancer patients and survivors. Different approaches of exercise programs have been established; however, the special interests of young adults (YAs) with cancer have rarely been considered in exercise interventions. Therefore, the study YOUng EXercisers (YOUEX) aimed to investigate exercise preferences in YAs. (2) Methods: YOUEX was a three-arm, patient preference-based non-randomized, longitudinal, pre-post exercise intervention, offering three different exercise modules to YAs during or after acute therapy (Module 1: online supervised group-based (M1); Module 2: online unsupervised (M2); Module 3: in-person supervised (M3)). The intervention period was 12 weeks with another 12-week follow-up period, the modules could be changed or amended after 6 and 12 weeks. (3) Results: 92 YAs were allocated to the study. At baseline, 50 YAs (54%) chose M2, 32 YAs (35%) M1 and 10 YAs (11%) M3. The analysis revealed high acceptability and feasibility of the online exercise programs (M1, M2). There was a high impact of the COVID-19 pandemic on the execution of M3. YAs showed diverse preferences in module selection due to differences in, e.g., cancer therapy status or favored level of supervision. (4) Conclusions: YAs need personalized exercise programs that consider their individual interests and needs. Online exercise programs can be a promising addition to existing exercise opportunities. They are an effective way to increase physical activity levels in YAs.

Is an Exercise Program for Pediatric Cancer Patients in Palliative Care Feasible and Supportive?-A Case Series.

(1) Background: Growing evidence indicates benefits through exercise programs in pediatric oncology throughout the whole cancer trajectory. This should include palliative care, too. This project analyzes the feasibility of a supervised exercise program offered during hospital and home-based care for children with advanced cancer diagnoses. (2) Methods: Four children (7-13 years old) with advanced cancer diagnoses participated in this project. It consisted of supervised exercise sessions offered once a week (30-90 min), mainly home-based, but also on an in- and outpatient basis. Regular data assessments included psychological and physical capacity-related endpoints and body composition. Details and contents of exercise sessions and adverse events were recorded. (3) Results: Exercise was feasible with 73 ± 9% adherence to the minimum number of planned sessions. The exercise offer was accepted until shortly before death. Effects on fatigue, quality of life and muscular endurance were noted. Participants showed major deviations from age-specific reference values. No exercise-related adverse events occurred. (4) Conclusions: The exercise program was safe, feasible, and might have served as a supportive tool to reduce overall burden. Evaluation of exercise as usual palliative care should be assessed by further studies.

Physical activity in 9-15 year-old pediatric cancer survivors compared to a nationwide sample.

INTRODUCTION: Sufficient physical activity (PA) has the potential to mitigate late effects of cancer, but objective data of PA levels in adolescents are scarce. The aim of this study was to investigate differences in PA behavior between childhood cancer survivors (CCS) and healthy peers. METHODS: PA levels of n = 74 CCS and n = 1304 healthy peers from the MoMo study aged 9-15 years were assessed with validated objective accelerometry and group means were compared. A binary multiple logistic regression was performed to investigate the potential predictors of PA. RESULTS: CCS spent significantly more time sedentary (p < 0.001) and less time in moderate-to-vigorous physical activity (p = 0.002) compared to the healthy cohort. Subgroup analysis revealed the largest deviations of PA levels for CCS aged 9-11 years who fulfilled international PA recommendations on significantly fewer days than MoMo (p < 0.01). Health conditions seem to be a predictor concerning the fulfillment of international PA recommendations by the WHO (p = 0.015). CONCLUSIONS: Our study identified vulnerable groups which seem to require targeted exercise and health behavior change programs to increase physical activity and reduce sedentary time. The presence of treatment sequelae as a significant predictor of insufficient physical activity underlines the need of multidisciplinary supportive care approaches.

Effects of strength exercise interventions on activities of daily living, motor performance, and physical activity in children and adolescents with leukemia or non-Hodgkin lymphoma: Results from the randomized controlled ActiveADL Study.

Objectives: Pediatric patients with cancer experience impairments in muscle strength and physical activity (PA) that may reduce autonomy during hospitalization. To determine the effects of strength exercise interventions on the accomplishment of activities of daily living (ADLs), motor performance, and PA in children with leukemia or non-Hodgkin lymphoma, we randomly allocated patients (4-18 years) immediately after diagnosis into two exercise groups. Methods: The intervention group (IG; n = 21) received a specific strength training combined with a standard care exercise program, whereas the control group (CG; n = 20) was provided standard care exercise program without any targeted muscle strengthening. After the baseline visit, participants were followed-up three times until intensive treatment cessation. We assessed physical function limitations using the Activities Scale for Kids© (ASK) and Functional ADL Screen. Secondary outcomes were PA levels using accelerometer and motor performance as measured by MOON-test (motor performance in pediatric oncology-test). Results: In both groups, ADL accomplishment had significantly increased (p < 0.05). However, no significant between-group differences for ASK outcome were noted. Motor performance was reduced in all motor abilities. Conclusions: Both exercise interventions were effective to maintain ADLs and motor performance during intensive treatment. In comparison, regular strength exercise interventions in the course of therapy tended to be more beneficial with regards to muscular explosive and endurance strength.

Effects of an Exercise Intervention on Gait Function in Young Survivors of Osteosarcoma with Megaendoprosthesis of the Lower Extremity-Results from the Pilot Randomized Controlled Trial proGAIT.

Limb preservation with megaendoprosthesis in adolescents and young adults (AYA) with bone tumors is associated with functional limitations and gait abnormalities. The proGAIT trial evaluated the effectiveness of an exercise program on gait function and quality of life, functional scales (MSTS, TESS), functional mobility, and fatigue as secondary outcomes. Eleven AYA survivors of malignant osteosarcoma with a tumor endoprosthesis around the knee (mean age: 26.6 (±8.4) years) were randomized into an intervention group receiving an 8-week exercise program or into a control group. Gait function was assessed via 3D motion capture and analyzed using the Gait Profile Score (GPS) and the Gait Deviation Index (GDI). GDI and GPS scores of participants suggest deviations from a healthy reference group. The exercise intervention had small-to-medium positive effects on gait score GDI |d| = 0.50 (unaffected leg), |d| = 0.24 (affected leg), subjective functional scores TESS |d| = 0.74 and MSTS |d| = 0.49, and functional tests TUG and TUDS |d| = 0.61 and |d| = 0.52. None of these changes showed statistical significance. Promising intervention effects suggest that regular exercise could improve lower limb function and follow-up care for survivors; however, a powered RCT as a follow-up project needs to confirm the pilot findings.

Multidisciplinary Network ActiveOncoKids guidelines for providing movement and exercise in pediatric oncology: Consensus-based recommendations.

BACKGROUND: Pediatric cancer leads to reduced participation in exercise and only few patients comply with national physical activity recommendations. Physically inactive behavior hinders motor development and increases physical and psychological adverse effects of therapy and incidence of sequelae. Currently, there is neither nationwide coverage nor uniform level of knowledge regarding exercise promotion. The objective of the guideline is to facilitate qualified exercise interventions through standardized procedures in addition to regular physiotherapy and overall avoid physical inactivity in pediatric cancer patients. METHODS: This guideline addresses the multidisciplinary treatment team and informs physiotherapists and decision-makers in tertiary care hospitals and health insurance companies. The requirements of the Association of the Scientific Medical Societies in Germany were followed. Contents were based on best practice experience of experts, patient advocates, as well as on scientific evidence. RESULTS: The guideline includes 11 recommendations. Recommendations 1-4 declare the relevance of implementing exercise interventions and address general framework conditions. Recommendations 5-11 focus on the design of exercise programs, prevention and safety issues, relative contraindications for specific training loads, and options to overcome barriers to exercise. CONCLUSION: This guideline summarizes existing and established structures and evidence in the context of movement and exercise in pediatric oncology. It takes into consideration the rights, varying needs, and characteristics of children and adolescents as well as national and international experience in this field. In the future, relevant research gaps need to be addressed by high-quality intervention studies to provide the scientific background for a stronger evidence-based guideline.

Design and Evaluation of an Outdoor Exercise Program for Pediatric Cancer Survivors.

Exercise programs for young people after cancer are not part of regular oncological care. This study describes and evaluates a regional outdoor exercise program and presents data with regard to the promoting and inhibiting factors for participation among pediatric cancer survivors. Exercise options, number of participants, and the cohort were evaluated descriptively for one year. A self-developed questionnaire was used to evaluate satisfaction, mood, motivations, and barriers to exercise. Overall N = 26 survivors (14.6 ± 5.5 years) participated in at least one activity in 2019 including try-out days (N = 10) and active weekend camps (N = 2). No adverse events occurred in 302 physical activity hours. Twenty-one survivors participated in the survey. The largest motivational aspect to participate was "to try out a new sport" (83.9%). Survivors reported "good mood", and 'being happy' after exercising. The largest barrier was concern about 'not being able to keep up with others' (38.1%). Around one-third (try-out day) and 50% (active weekend camp) of survivors did not feel confident to continue exercising outside the supervised exercise oncology program. This survey shows high enthusiasm for this exercise program with different outdoor activities and suggests that similar interventions may be accepted by this population.

A National Implementation Approach for Exercise as Usual Care in Pediatric and Adolescent Oncology: Network ActiveOncoKids.

The diagnosis of cancer as well as accompanying acute and late effects of treatment are influencing physical activity behavior of patients with childhood cancer and survivors. Research has shown that a pediatric cancer diagnosis is associated with impairments of physical performance, and function, as well as reduced physical, and psychosocial, health conditions. From an ethical perspective, lack of knowledge of health care providers, lack of physical activity promotion, and environmental, and structural barriers to physical activity restrict children's right to move and actively engage in physical activities. Network ActiveOncoKids is a German-wide initiative with the main goal of enabling children, adolescents, and young adults with exercise opportunities during and after cancer treatment. Since the network's foundation in 2012, Network ActiveOncoKids focuses on: (1) physical activity support for patients and families, (2) policy change to establish structures and guidelines, and (3) generating evidence through scientific projects. The purpose of this paper is to present an overview of Network ActiveOncoKids structure, aims, and projects. This topical review will highlight the network's structural development, research work, and implementation progress of exercise programs for patients with pediatric cancer and survivors, link international collaborations, and discuss future directions.

The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) Study: Protocol for an International Mixed Methods Study.

BACKGROUND: Survivors of childhood cancer represent a growing population with a long life expectancy but high risks of treatment-induced morbidity and premature mortality. Regular physical activity (PA) may improve their long-term health; however, high-quality empirical knowledge is sparse. OBJECTIVE: The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) study comprises 4 work packages (WPs) aiming for the objective determination of PA and self-reported health behavior, fatigue, and quality of life (WP 1); physical fitness determination (WP 2); the evaluation of barriers to and facilitators of PA (WP 1 and 3); and the feasibility testing of an intervention to increase PA and physical fitness (WP 4). METHODS: The PACCS study will use a mixed methods design, combining patient-reported outcome measures and objective clinical and physiological assessments with qualitative data gathering methods. A total of 500 survivors of childhood cancer aged 9 to 18 years with ≥1 year after treatment completion will be recruited in follow-up care clinics in Norway, Denmark, Finland, Germany, and Switzerland. All participants will participate in WP 1, of which approximately 150, 40, and 30 will be recruited to WP 2, WP3, and WP 4, respectively. The reference material for WP 1 is available from existing studies, whereas WP 2 will recruit healthy controls. PA levels will be measured using ActiGraph accelerometers and self-reports. Validated questionnaires will be used to assess health behaviors, fatigue, and quality of life. Physical fitness will be measured by a cardiopulmonary exercise test, isometric muscle strength tests, and muscle power and endurance tests. Limiting factors will be identified via neurological, pulmonary, and cardiac evaluations and the assessment of body composition and muscle size. Semistructured, qualitative interviews, analyzed using systematic text condensation, will identify the perceived barriers to and facilitators of PA for survivors of childhood cancer. In WP 4, we will evaluate the feasibility of a 6-month personalized PA intervention with the involvement of local structures. RESULTS: Ethical approvals have been secured at all participating sites (Norwegian Regional Committee for Medical Research Ethics [2016/953 and 2018/739]; the Oslo University Hospital Data Protection Officer; equivalent institutions in Finland, Denmark [file H-19032270], Germany, and Switzerland [Ethics Committee of Northwestern and Central Switzerland, project ID: 2019-00410]). Data collection for WP 1 to 3 is complete. This will be completed by July 2022 for WP 4. Several publications are already in preparation, and 2 have been published. CONCLUSIONS: The PACCS study will generate high-quality knowledge that will contribute to the development of an evidence-based PA intervention for young survivors of childhood cancer to improve their long-term care and health. We will identify physiological, psychological, and social barriers to PA that can be targeted in interventions with immediate benefits for young survivors of childhood cancer in need of rehabilitation. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/35838.