Inclusion Criteria:

- Patients greater than 4 years of age at Memorial Sloan-Kettering Cancer Center

- Must be undergoing hematopoietic stem cell transplantation (either autologous or
allogenic) in conjunction with a conditioning regimen that includes TBI (single or
multiple fraction)

- Functional central venous catheter

Exclusion Criteria:

- No subjects will be excluded from the proposed research study for demographic
reasons. Treatment with growth factors, such as keratinocyte growth factor (KGF),
will not be grounds for exclusion.

- Subjects who will receive radiation therapy within 5 days prior to TBI will be
excluded.

- Subjects who will receive systemic antineoplastic chemotherapy within 7 days prior to
TBI not have research bloods collected. Only urine will be collected from these
patients.

- Subjects less than 4 years of age will be excluded because they are not treated with
TBI.

- Based on current knowledge, we will not a priori exclude patients based on disease
status (ie, patients in or out of remission will be included in this study), type of
disease(ie, chromosomal breakage syndromes), or previous therapies (unless exclusion
criteria is met).