The Childhood Cancer Survivor Study (CCSS) is researching the long-term effects of cancer treatments on young survivors. The study will include about 50,000 people who survived cancer diagnosed before age 21, between 1970 and 1999. Researchers will look at how treatments like radiation (high-energy rays), chemotherapy (strong medicine to kill cancer cells), and surgery affect their health over time. They will compare these survivors to 10,000 of their healthy siblings. The study wants to find out how these treatments might affect things like heart health, having children, and getting new cancers. They will also collect saliva, blood, and tissue samples for further research.

To join, you must have survived certain types of cancer for at least five years and been diagnosed before 21. You should speak English or Spanish and live in the U.S. or Canada. If you had non-cancerous tumors, you can't join. Healthy siblings will be used for comparison.

• Study checks health effects of past cancer treatments.
• Participants include cancer survivors and their siblings.
• Samples collected to help future research.