Expression of the cell cycle regulator p16INK4a increases with age and toxic stressors. In mice, both radiation and chemotherapy are known to increase p16. Due to its influence on age-related regenerative capacity, p16 is an excellent candidate biomarker of physiologic reserve that may identify patients able to withstand the stressor of chemotherapy (low p16) from those unlikely to tolerate chemotherapy (high p16). That is, expression of p16 may predict physiologic, rather than chronologic, age. Such findings could have implications for care of cancer survivors and treatment decision-making in cancer patients.

STUDY OBJECTIVE: This is an observational pilot study to determine the feasibility of isolating p16INK4a in CD3+ T lymphocytes in adults treated with chemotherapy for cancer during childhood.

At St. Jude Children's Research Hospital, survivors who meet the eligibility criteria will be identified from SJLIFE protocol participants. After signing consent, the subject will have a blood specimen collected at the same time as the blood draw for the SJLIFE protocol. These samples will have T cell isolation performed then placed on ice and stored until batch shipment for investigation of p16 expression.

Inclusion Criteria:

• Enrolled in the SJLIFE study at St. Jude children's Research Hospital.
• Survivor of childhood cancer.
• Is 18 years of age and older.
• No evidence of cancer recurrence.
• Received prior chemotherapy (prior radiotherapy is allowed).

Exclusion Criteria:

• Inability or refusal to give consent.

Participants will be childhood cancer survivors enrolled in the long-term follow-up study at St. Jude Children's Research Hospital.