This randomized clinical phase III trial studies how well web-based physical activity intervention works in improving long term health in children and adolescents with cancer. Regular physical activity after receiving treatment for cancer may help to maintain a healthy weight and improve energy levels and overall health.

PRIMARY OBJECTIVE:

I. To compare the effects of a rewards-and web-based physical activity intervention that includes structured social interaction between participants to the same web-based physical activity intervention that does not include structured social interaction on fitness among children and adolescents following treatment for cancer.

SECONDARY OBJECTIVES:

I. To evaluate the effect of a rewards-based, socially interactive web-based physical activity intervention on markers of cardiometabolic health among children and adolescents following treatment for cancer (compared to the same web-based physical activity intervention without social interaction).

II. To evaluate the effect of a rewards-based, socially interactive, web-based physical activity intervention on physical activity, quality of life, fatigue, and school attendance among children and adolescents following treatment for cancer (compared to the same web-based physical activity intervention without social interaction).

III. To determine if the effect of a rewards-based, socially interactive, web-based physical activity intervention on markers of cardiometabolic health is mediated by changes in fitness among children and adolescents following treatment for cancer (compared to the same web-based physical activity intervention without social interaction).

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients receive educational handouts about physical activity and are encouraged to increase physical activity to at least 420 minutes per week. Patients wear a physical activity tracking device daily and upload data at least once a week to the device app/website. Patients also access the limited version of the app/website to get basic information related to their physical activity. Patients will not be told of the details of earning of monetary incentives. Their activity will be monitored during the 6 month intervention period and will receive all earned gift cards or prizes after the intervention period ends. The patient will be encouraged to continue to wear the device for the remainder of the study, although they will no longer be earning monetary incentives.

ARM II: Patients receive educational handouts about physical activity and are encouraged to increase physical activity to at least 420 minutes per week. Patients wear a physical activity tracking device daily and upload data at least once a week to the device app/website. Patients also access the full version of the interactive-reward based device app/website to see their activity, earn activity points, see other's activity, and interact with other patients randomized to this study arm. Patients will receive additional details about how to earn gift cards or prizes for engaging in the intervention and will be rewarded for all earned incentives throughout the 6 month intervention period. The patient will be encouraged to continue to wear the device for the remainder of the study, although they will no longer be earning monetary incentives.

After completion of study, patients are followed up at 24 and 48 weeks.

Inclusion Criteria:

• All cancer cases with an International Classification of Diseases for Oncology (ICD)-O histologic behavior code of two "2" (carcinoma in situ) or three "3" (malignant), in remission
• Patient must have completed curative therapy (surgery and/or radiation and/or chemotherapy) within the past 12 months at a Childrens Oncology Group (COG) institution
• Patients must have a performance status corresponding to Eastern Cooperative Oncology Group (ECOG) scores of 0, 1, or 2; use Lansky for patients =< 16 years of age
• At the time of consent, patient or parent/guardian reports less than 420 minutes of moderate to vigorous physical activity over the last week
• Patient and at least one parent/guardian are able to read and write English, Spanish, and/or French; at least 1 parent/guardian must be able to read and write English, Spanish, and/or French in order to assist the patient with using their physical activity tracking device account
• All patients and/or their parents or legal guardians must sign a written informed consent
• All institutional, Food and Drug Administration (FDA), and National Cancer Institute (NCI) requirements for human studies must be met

Exclusion Criteria:

• Patients with previous hematopoietic stem cell transplant (HSCT)
• Patients with significant concurrent disease, illness, psychiatric disorder or social issue that would compromise patient safety or compliance with protocol therapy, or interfere with consent, study participation, follow up, or interpretation of study results
• Female patients who are pregnant are not eligible; women of childbearing potential require a negative pregnancy test
• Female patient who is postmenarcheal and has not agreed to use an effective contraceptive method (including abstinence) for the duration of study participation
• Patients with a cognitive, motor, visual or auditory impairment that prevents computer use (e.g. unresolved posterior fossa syndrome) are not eligible